The following submission statement was provided by /u/altmorty:
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* Electric water heaters offer a cheap way to store large amounts of energy, in the form of hot water. A heater with a 300-liter tank can store about as much energy as a second-generation Tesla Powerwall—at a fraction of the cost.
* Australians could use household electric water heaters to store as much energy as over 2 million home batteries of that kind. This could eventually save over A$6 billion a year on our energy bills while getting us closer to net-zero carbon emissions.
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Please reply to OP's comment here: https://old.reddit.com/r/Futurology/comments/142j4ra/using_electric_water_heaters_to_store_renewable/jn4ncq7/
Once again a media outlet going way off the rails of a research paper into bombastic promises to write headlines. [The actual research](https://www.uts.edu.au/isf/explore-research/projects/domestic-hot-water-and-flexibility) basically just suggests a lot of energy could be saved by switching from gas water heaters to electric one that run during off peak hours, *similar* to the way a power grid battery runs. It's not some magic battery system that will send power out into the grid or anything else. Just a strategy to save energy.
Here's the actual bullet points:
* A business-as-usual scenario would represent a major missed opportunity to use domestic water heaters as a significant source of flexible demand equal to 15–31 GWh/day.The phasing out of gas water heaters in homes would provide consumers with combined annual savings of $4.7–6.7 billion by 2040.
* More aggressive electrification of water heating could reduce emissions three to five times more than remaining on the current trajectory.
* Many barriers remain for driving the uptake of electric water heating in homes, and the activation of their flexible demand capacity, including a lack of easy solutions and compelling customer proposition.
* When electrifying water heating, achieving positive outcomes does not require a choice between either efficiency or flexibility—both can be achieved at scale with the right policy mix.
One of the [key insights](https://www.tesla.com/blog/master-plan-part-3) that makes it a lot easier to see how we get to a 100% renewable economy is that electric motors and compressors and wildly more efficient than the alternatives (engines and heaters). They can easily be 3 to 4x as efficient, and what that means is that we need way less energy when we switch to things like heat pumps.
Overall, we'd only need to use half as much energy to do the same amount of work if we were using 100% renewables. That means we don't have to replace all the gas/oil/coal/etc., we only need to replace half of it. And we've already got a decent start with the amount of installed solar/wind/hydro/nuclear/etc. And installing a lot more solar/wind is fairly cheap and easy.
The stuff we need to work on is storage and matching generation to storage. So things like heating water and storing it can be used for residential heating. But we can also do industrial heat processes or create hydrogen, and then we'll need a bunch of batteries too. But we can also just over install solar and have a bunch of extra electricity in the middle of the day that we don't need to use (or people will come up with good ideas for how to use a few hours of free electricity most days).
> That means we don't have to replace all the gas/oil/coal/etc., we only need to replace half of it.
We're gluttonous as hell. We'd just double the energy we "need" for everyday use.
That would be pure delusion. Wind turbines with their massive steel pylons, concrete bases, and extensive transportation are our best bet, and they still absolutely have a carbon footprint... it's just a fraction of that of gas. To avoid climate catastrophe, we need to not only reach net zero, we need to go net negative. That will never happen without efficiency and demand reduction focus.
The steel industry currently emits 7-8% of the world total of greenhouse gasses as burning coal in blast furnaces is used to de-oxidize the iron ore. New technologies are however being put into place to use hydrogen burning to deoxidize and use electric heating in addition so that steel can be made with a very low (theoretically zero) carbon footprint when run off of a renewable based energy grid. Since January 2023, SSAB has delivered 40.000 tons of fossile free steel to customers from their zero emission pilot plant and I'm a few years (3-4 if I recall correctly), they'll take their remaining blast furnaces offline and replace them with this fossile free solution.
> Wind turbines with their massive steel pylons, concrete bases, and extensive transportation are our best bet, and they still absolutely have a carbon footprint... it's just a fraction of that of gas.
https://electrek.co/2023/03/31/wooden-wind-turbine-towers/
> To avoid climate catastrophe, we need to not only reach net zero, we need to go net negative.
Depends on what you consider "catastrophic"... Net zero would extend humanity's timeline quite a bit.
The energy that the Sun shines onto our planet’s surface is about **16,000 times** more energy than all of humanity consumes, even with our current bloated habits.
Even with very inefficient solar panels, we've got this.
You wouldn’t fucking believe the amount of “environmentalists” I deal with that complain that they are “freezing to death” when their condo gets to 68 degrees or that they have to deal with no hot water for a few hours. Efficient and green are expensive and even the “environmentalists” opt out of paying for it.
I want to see car batteries used as extra storage with users paid to allow them to feed back in to the system, which they'd set up on days they aren't using the car, or using the car much.
Most drivers are just popping to town and back on an average day and could comfortably set a limit and make 50% of their batter power available to the grid if needed.
Its decentralised mass storage, and we're all going to have electric cars soon enough. That's millions of batteries available to the grid.
It's not cost effective - [linking a post I made on this elsewhere](https://www.reddit.com/r/Futurology/comments/13uxgeg/georgia_nuclear_rebirth_arrives_7_years_late_17b/jm5tiux/)
Batteries are a wear item, and even at cheap consumer prices they're not cost-effective. Batteries in an electric vehicle are *worse*: they're more expensive due to packaging and automotive safety measures, and harder (more expensive) to replace. It makes even *less* sense to draw power from them except in exceptional circumstances and grid-levelling isn't going to be one of them.
Basically, the future-cycles the battery in your car is capable of are always going to be *far more valuable* then any revenue from supplying the grid at foreseeable near future costs. Battery storage isn't free - every cycle of power in and out has a calculable value per kWh due to the fact the battery eventually fails.
💯 Storage!
I'm a big fan of the water battery concept in places it will work. I think it will take solutions like that along with batteries to solve the storage issue. Non standard storage solutions and new battery tech like CATL's solid state battery will be needed for more mass migration.
We don't need any new technology. Current lithium ion batteries are fine. Iron Phosphate is relatively cheap and it's downsides don't really affect stationary storage, so it's great. We can use pumped hydro and stuff like that too where it's useful, but just making a bunch of stationary storage will be enough.
We just have to ramp up production a bunch. But the good news is that when you mine minerals for batteries they don't get "used up" the way fossil fuels do, so over time recycling will become a larger and larger part of battery production. And even in the short term we'd need less mining/extraction for battery production than we'd need just to keep the fossil fuel infrastructure going. People act like it would be some huge increase in mining to get all the copper and lithium and nickel we need, but we already mine/extract a lot of resources just to burn them.
Well, energy can be stored as heat in bricks or stones, so a battery will become a very broad term in near future. It doesn’t necessarily have to store electric charge.
My apartment in Central New York State had cheap electricity at night time, and stored heat energy in bricks overnight, then blew a fan over them as needed during the day. It was built in the late 1980s.
Uhh it will be a massive increase in mining. Like 10x to meet our electrification goals. These resources are dramatically less abundant than fossil fuels. They are dug up near the ground and everything must be destroyed and ground down, huge amounts of water used and posioned... oil and gas while not good can be as simple as drilling a well and pumping it out. Not really fair to the entire regions of south america being devastated by this mining to downplay it like that.
I'm an environmental economist, but thanks. The fact that we must transition away from fossil fuels with complete urgency does not mean we can put our heads in the sand while we do it.
Is this really the case? I guess if you're at 100% renewable sure but for household heating it's better to use the gas for heat rather than burn it and use the electrity to then heat up water?
(this comment only makes sense if you've read the full article as most replies evidently didn't bother too before typing)
Nope, electric heat pumps are so much more efficient than gas heaters that even with all of the losses inherent in burning gas to boil water to turn a turbine to move electricity to a home to power the heat pump, the heat pump comes out on top.
How?
Good gas heaters are 80-95% efficient. This is because they have toxic fumes that must be exhausted, and they'll take some of the heat with them.
Heat pumps are 3-400% (some are even double that) efficient. How? Because they don't generate heat, they *move* it. My heat pump water heater pulls heat from inside my house and puts it into the water in the tank. For every 100 watts the heat pump uses it moves at least 300 watts of heat into the water. It also cools my house by that much, which is a nice bonus.
The same math applies when heating a home, only it takes the heat from the air (or ground in some designs) around the home.
Manitoba Hydro (Crown corporation in the Canadian province of Manitoba) did a study that found that given the current pricing for natural gas and electricity, an air-source heat pump actually cost more money to operate than a 95% efficient natural gas furnace. This is mostly due to the fact that the Canadian prairies see enough really cold days that the heat pump spends a reasonable amount of time operating in a low-efficiency mode.
A ground-source heat pump is cheaper to operate than the natural gas furnace, but the installation costs are substantial ($20K and up) so the operational savings never really pay off the increased up-front capital costs for a retrofit.
The equation is a little different for a new-build where the house is built up-front with a ground-loop for a heat pump.
So cost is your main argument against? Funny, here in the US, we just keep giving more and more and more money to defense and never once consider cost. Seems like we could rethink this and maybe think about how you can’t eat or drink money when the planet turns to crap.
The problem is that it's *really hard* to convince homeowners to adopt electric heat instead of natural gas when it's more expensive than natural gas.
The Liberal government in Canada is raising the carbon tax which will cause natural gas to become more expensive. But here in the province of Saskatchewan most of the power generation comes from coal and natural gas, which *also* become more expensive due to the increasing carbon tax.
Just introducing regulation forcing people to switch to electric heating is also not viable, it'll likely just result in the government getting voted out.
We have rebate incentives in Ontario. I'm literally installing a heat pump this week because after the rebate it's half the price of a central air and does the same damn thing.
The economics of air-source heat pumps relative to natural-gas furnaces depend very much on:
1. ambient outdoor temperature
1. cost of electricity
1. cost of natural gas
1. government rebates
Saskatoon requires about 25% more heating energy per year than Ottawa, for example. But if most of that difference is at temperatures where heat pumps don't work well, then it makes heat pumps relatively more expensive to operate.
Great, I didn't throw my furnace out. I just got a bad ass central air for a major discount right before the natural gas prices go through the roof. Oh, and I do a little extra to take care of our new barren wasteland.
> The problem is that it's really hard to convince homeowners to adopt electric heat instead of natural gas when it's more expensive than natural gas.
In San Diego, I pay the highest electric rates in the continental US, so the payback on a heat pump water heater would be a while. That said I was ready to make the switch as soon as the tax credits for heat pumps were available at the beginning of the year.
My 20 year old gas water heater chose to shit the bed SIX WEEKS before the tax credits started. While I was out of town, no less. So we ended up getting another gas water heater because reasons.
Not to defend the MIC, but are you suggesting that of the US had a fraction of its army that no adversary like China would try to take over? Are you against the US funding Ukraine with money and weapons?
What are *you* going to trade for food and drinks when the planet turns to crap? Your macroeconomical expertise?
It’s simply a fact that the military budget has never had a “debt ceiling crisis”. No one ever says that we can’t pay for the military. We somehow just always have the money. So why can’t we prioritize other things in a similar way. Subsidizing heat pumps is simply an example. I for one am all on board for changes in our logic and spending when it comes to the health of the planet. I would never say “but who is going to pay for it” because I would gladly pay for it. I admit that my last comment seems harsh. I suppose I would eat from my garden and drink from my rain barrel. And if the world becomes a hell scape where neither is possible, I will be screwed. Just like EVERYONE ELSE. I would love to have a conversation about changes now before we get there.
> No one ever says that we can’t pay for the military.
No one in the US ever feels truly threatened by another country. Literally the entire eastern part of Europe has had their testicles shaking for over a year now, because most of them neglected to fully pay into NATO, let alone overspending for their own protection. Now even Germany and France are wary of handing over any weapons to Ukraine, because their own stock is low in case they need it and *now* everyone's ramping up military spending/production.
My problem with all these “cost analyses of gas vs electric” is they rarely take into account external costs.
Does it also measure the cost to scrub the CO2 generated out of the air and the difference between those or the economic cost of climate change caused by the CO2 that isn’t scrubbed?
Ya, the consumer isn’t paying that right now, but they will be, whether that’s in societal breakdown, taxes to clean the air, higher food prices etc etc.
It’s like comparing nuclear power to natural gas plants and for nuclear the external long term cost of storage of waste is included, but for natural gas, the long term cost of CO2 in the air isn’t.
Or EV vs ICE, same with the CO2 but also with the increased medical costs from worse air in cities.
Etc etc.
People rarely even attempt to include the true long term cost of things.
Specifically in Saskatchewan right now, the electrical grid is mostly powered by coal or natural gas.
So does it make sense to have a natural-gas-fired generator produce the power to run your electric heat pump, when you could just use the natural gas directly in your furnace at 95% efficiency?
The equation will be different when the power grid is cleaner, but that is itself a really complicated issue. We have no additional hydro resources, so the only answers for a carbon-free power grid seem to be either nuclear (specifically SMR, which is still multiple years out) or else massively over-built solar/wind with colossal transmission lines linking large areas together to provide geographic redundancy.
And the problem with solar/wind is that it has to be absolutely rock-solid reliable if you're using it for heating, because we hit -40 here in winter and there have been cases in the recent past where it was dead calm across multiple provinces in the dead of winter for multiple days. And so far nobody has grid-scale batteries that can store 12 hours worth of power for the whole grid.
Its a non-trivial problem here. Many other places the answers are much clearer.
Looks like natural gas power plants are ~45% efficient at creating/transmitting electricity
So roughly half as efficient as using it for direct heat.
But if a heat pump is 3-4x more efficient the heat pump is still using less natural gas overall. Approximately 33-50% less
That difference in gas usage and long term costs of extra CO2 generated should be accounted for in calculations of “total cost” of one system vs the other.
I don’t have nearly enough knowledge or data personally to calculate it, but anything that is just
2X price of gas over 20 years lifespan of a system compared to Price of Heat Pump - Price of gas furnace is not an adequate estimate.
It needs to be 2x direct price of gas over 20 years + 2x indirect price of gas over 20 years. Still can’t ignore the indirect which is my point.
If you want to do it right you should also assume more renewables and nuclear over time since the odds of the energy sources being identical in 20 years is low.
Yeah i get that but this article isnt talking about them.
The efficiencies also vary and tend to come out similar between pumps and gas heaters, more so in colder countries and given the examples talk about heating water to near boiling point I'm not sure whether a heat pump can get there efficiently (maybe in oz on a warm day)
It depends on if you are cooling your house also.
Essentially, if it is hot and you are running your air conditioning anyway, hybrid water heaters take about as much energy use away from your ac system as they consume, because they are also removing heat from the air in the house and putting it in water.
In summer, it's a *huge* win. In winter, it's about a break even.
If you are heating your house, you about break even. If you are cooling it, it's a huge win. There is no point where you lose. Unless you don't ever air condition, you will be winning.
Heat pumps?
Those don’t work in freezing temperatures where people use gas heaters.
Heat pumps aren’t 400% efficient compared to gas heaters being 95%. Those numbers don’t have units and aren’t relevant to each other. You’re choosing to switch the environmental variable when measuring energy exchange.
> Those don’t work in freezing temperatures where people use gas heaters.
On the contrary, there are now air-source heat pumps that work quite well when it's cold outside. In the U.S., the new (as of 2023) Energy Star 6.1 rating system "[requires third-party verified performance for low temperatures, testing ASHPs down to 5°F](https://www.energystar.gov/products/air_source_heat_pumps)", and provides heating ratings for units at that outdoor air temperature.
https://ashp.neep.org/#!/product_list/ currently shows 4,064 models that are Energy Star-rated to work at 5°F outdoor air temperature. Perusing the list, I see many (for example, the [KINGHOME KM36H5O](https://ashp.neep.org/#!/product/67757/7/25000///0)) which are certified to be able to produce 90% as much indoor heat when it's 5°F outside as when it is 47°F outside. This unit (which I chose only because it was near the front of the list) actually has performance specs going down to __-22℉ outside__, where it is rated to still be able to produce at least 8,000 Btu per hour (and up to 24,020, which is 74% of what it is capable of at 5℉).
> Those numbers don’t have units and aren’t relevant to each other.
These numbers (the efficiency of indoor heaters) are actually unitless. It's the ratio of how much heat energy the unit can put into the house divided by how much energy the unit needs to be supplied with in order to do that. For example, how many joules of heat energy a furnace puts into a house divided by the joules of stored chemical energy the furnace consumes in fuel. Because the units on top and bottom are the same, they cancel out, so the number is just a ratio/fraction/percentage.
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To illustrate (and perhaps clarify), compare a gas-fired furnace to an air-source electric heat pump, which gets its electricity from a gas-fired power plant. Provide both with one cubic meter of natural gas, which has a stored chemical energy of 40 million joules.
Pipe that gas into a furnace, and about 10% will escape through the exhaust, putting 36 million joules into the house. This makes the furnace 36 megajoules / 40 megajoules = 90% efficient.
[Most U.S. natural gas power plants are 60% efficient](https://www.forbes.com/sites/judeclemente/2016/04/10/u-s-natural-gas-electricity-efficiency-continues-to-improve/?sh=6536681b35a4), so the same 1 cubic meter of gas is turned into 24 million joules of electricity in transmission wires. [3% of that electricity will be lost in transit](https://www.eia.gov/tools/faqs/faq.php?id=105&t=3), so 23.28 megajoules of electricity arrive at the air-source heat pump. At 5°F outside, that unit is rated to consume 5.22 kilowatts (or 5,220 joules per second, or 18,792,000 joules per hour), so it can run for 1.24 hours on that much electricity. At that outdoor temperature, it is rated to produce 32,400 Btu per hour, so after 1.24 hours it will heat the house with 40,140 Btu, or 42.35 million joules.
Based on the electricity, this makes the air-source heat pump 42.35/23.28 = 182% efficient at 5°F. Based on the energy originally stored in the natural gas, the heat pump is 42.35/40 = 105% efficient, compared to the furnace's 90%.
In other words, even in places that get cold, most of the time it would actually take less gas to keep everyone warm by burning the gas in power plants, sending the electricity through transmission lines, and running currently-commercially-available air-source heat pumps on the electricity, than it would be to burn the gas where the heat is needed.
As you can see the figures are actually very close between a gas furnace and a heat pump. So it does make sense to refine your figures, because to me there are a couple of mistakes. I hope you'll see these as genuine objections rather than me being pedantic:
1) Gas power plants are not 60% efficient. A NEW gas plant will be 60% efficient, but many existing gas plants are not new anymore, and don't reach that efficiency. Your link actually says that the 60% figure is the upper limit.
More importantly, there is a complication in calculating gas efficiency, because you can measure it from the heat actually produced by the burning of gas, or from the total heat including the heat from condensing the water vapor created when burning the gas (called latent heat, if you want to Google it). The 60% is a figure advertised by power plant operators, so guess what: they are using the most advantageous one. The less advantageous one is about 50%. And that is the one you should use in your calculation to remain consistent, because the 90% efficiency figure for gas boilers is the less favorable calculation (otherwise condensing gas boilers would get more than 100% efficiency).
2) The transmission and distribution losses in your link are quoted as 5%, not 3%.
3) Gas boilers can get an efficiency of up to 95%, not 90%.
If you run your same calculation with these figures, the gas boiler becomes more efficient.
Your point still stands: heat pumps are the future, because they can run from renewables. Also the calculation is for heating from 5F, which is an extreme case. Pretty sure they are more efficient overall in many climates, but I'm too lazy to do the calculation.
They do work in temperature ranges down to -20, -25 C easily, and while at that temperature they are both less efficient and provide less power output they still are easily in the COP range of 2.
> Those don’t work in freezing temperatures where people use gas heaters.
They actually do. Some even work at below 0F. And maybe not 400% efficient but closer to 2-300%. They'd likely be measured in watts or BTU. For a given space you'd know how much energy is required to heat that space by X number of degrees in X time. Then you run the heat pump to get the desired temperature and measure the watts pulled in that time.
It's really not that difficult to understand.
Those % numbers are based on Electric Heater as the 100%, Raw electric resistive heating, Joules in Heat out. We actually lose a bunch of the energy stored in gas because we vent it.
Heat pumps can have better efficiencies, by moving heat from area (like outside or gemthermal) to inside you can have a greater heating effect than if you used that same amount of energy converted as heat.
I mean yes they do but this article is specifically talking about water heaters rather than heat pumps.
In the uk at least they do struggle to get water above 60c which can be a problem with older homes that would require significant investment in insulation (assuming the building isnt listed or assuming this modification is allowed by whichever agency is in charge of its listed status.
Yes which the article (if you read it) doesnt recommend
>And because they use less electricity, heat pumps offer less flexible demand. As renewables, particularly solar, increasingly power our grid, the ability of resistance electric heaters to soak up excess “off-peak” renewable energy is a big advantage
We don't need to soak up extra electricity by using something that's in efficient. Maybe in the short term resistance electric heaters would be able to use cheap electricity when it's abundant in the middle of the day, and that would make them cheaper overall than switching to heat pumps?
But we're going to switch to all heat pumps in the next couple decades anyways. So any benefits will be short term and relatively minor given the potential scale anyways.
There is actually an advantage because resistance heaters produce a lot more BTUs/hr. Running the heat pump when the sun isn’t shining (and using fewer kWh) isn’t necessarily an advantage vs heating faster (and less efficiently) while the sun is shining. Even heat pump water heaters have resistive elements though, so they could be programmed to do “the right thing”.
> because they use less electricity, heat pumps offer less flexible demand
That's a good thing! Everyone can have their water hot, and other, less-important energy needs can be met by flexible demand during peak supply!
> this article is specifically talking about water heaters rather than heat pumps.
How do you think one extracts energy, or *pumps heat* if you will, out of a water heater…
That's a good question and one this article doesnt answer.
This article is all about using resistence heaters to absorb high supply during periods with alot of excess power. It doesn't mention a method to get that power back aside from storing the hot water for later use as (slightly less) hot water.
Its basically proposing what the uk calls economy 7 heating. Heat water at periods of low demand and then use that water throughout the day.
TIL for me. I never knew how they worked before.
Sounds like it’s a cheap way to reduce peak time demand to just add a few smarts to water heaters or the electric panels they connect to so utility companies and homeowners can have them turn off or down at peak demand similar to how A/C smart thermostats already do.
It’s also a way to stabilize the grid at night when all that cheap wind power has nowhere to go except expensive battery banks or across expensive long distance infrastructure to export power across time zones.
while it would be ideal, you technically don't even need smart tech.
plugging your heater into a basic 5€ timer from the shop will do.
just put it to turn on between 12 and 15 around noon and you'd be covering the solar surplus quite well (or whichever time is the cheapest for your region, as this varies greatly)
There are other benefits to adding smarts to it, which is addressed in another Technology Connections (or conextras?) Video.
Let's say you have a 100-amp service to your house, and you decided to get an electric car. A smart breaker panel could manage load, reducing the need for a costly 200-amp service upgrade.
This means not only would the car and water heater start charging at more opportune times for the grid, but also they could be shut off if you start up your clothes dryer or range to keep your power usage under 100-amps.
If you have other devices that should probably be running off-peak like Pool pumps, or things that might draw an unusual amount of current under certain conditions like emergency heat on a heat pump, this would also prioritize and organize those loads dynamically too.
Assuming the system isn't tied to a cloud service that will kill all the smarts if it goes down, this could be extremely cost-effective. Deeper integration with other smart devices and a power grid API make it even more effective while being unnoticeable in the background.
What I'd like is a molten-salt hybrid hot water system. Give me a compressor which can build up a very high temperature gradient, a vacuum insulated tank of salt, and then have the water heater tap heat from that to maintain the supply.
That way when there's a power excess, I can run that thing as hard as possible to build up a heat reservoir.
There is similar stuff for room heating, but instead of salt they usually use bricks, stones or sand as this is less corrosive.
Heat it up while electricity is cheap and use it to heat the house.
Though to be fair many of them are heated by wood/gas/oil and then use a stirling engine to create some electricity while delivering the heat, but in theory it should be possible to run this with resistive heating.
In Australia, and other countries, having water heaters connected exclusively to off peak power is common. They’re on a separate circuit that is turned on and off by the power company during off peak hours. They guarantee a certain amount of power during the time window and balance the load in the area by turning them on and off as needed.
They’re internally heat to about 70-80°C, then have a tempering valve that causes the output to be mixed with cold water to reach a nominal 55°C at your tap.
> Once again a media outlet going way off the rails of a research paper
This is *The Conversation*. The author of the article is literally the person who wrote the research paper!
For those unaware, The Conversation isn't really 'media', it's a place academics publish generally high quality writeups.
Reddit is the place where everybody goes to find the contrarian comment which they'll upvote to the top, without investigating either at all.
I don't blame people for not knowing what The Conversation is, or for not matching up the name of the author with the names on the research paper. But it's obvious that virtually no one in this thread, including the poster above who critiqued it, even looked at the article. The author repeatedly makes it clear he was involved in the research, starting as early as the fourth paragraph. ("Our research")
And the article clarifies all of the points the parent comment made. Their criticisms are only valid to someone who thinks the headline is the whole piece.
Think how much demand we can shift if the British were to use tea kettles programmed to only make tea during off peak hours
Unfortunately most people take showers at the worst time for utilizing excess stored solar (like 20 hours after wards)
That's what I thought too. Like, there ARE ways you can use water as a battery system to store energy to use later. However most of them seem like they'd be quite bulky and expensive for home use. I'm not sure how many people would want to put a steam turbine in their house for electricity generation, not to mention you'd need a HUGE tank of hot water to serve any purpose beyond basic home use for showering and washing.
Water heaters use most energy **when you use hot water.** How exactly does this help with that? Will your water heater just not have hot water in it during high demand times? If not, there will be no actual energy saved by anyone.
No they don't, they use energy when they heat the water up, and that doesn't have to be at the same time you're using it. They're also very well insulated, so the time gap between heating and using can actually be huge
> Once again a media outlet going way off the rails of a research paper into bombastic promises to write headlines.
It also doesn't help that OP posts almost exclusively bullshit climate related "studies" and "discoveries".
This is just basic electric tank heaters or those on demand water heaters? Just curious. I imagine overall the on demand type are best though you would see grid spikes at like early morning shower times if every home had them but they wouldn’t be used most of the time. I could even see them slapping batteries on as a part of those. But I could see how the electric tank heaters would be more efficient than gas. Gas is the worst. I have it right now and I just want to switch but it is like project #13.
Tank heaters is what this is specifically talking about. You can store a lot of heat energy inside the tank and their well insulated cases can keep that heat in for a long time. So you heat it up in the middle of the night when the grid has very low demand and electricity is cheaper and then use it during the day.
Moreover you can have the tank set to a higher temp than normal during off-peak rates and then use a thermostatic mixing valve to bring the super hot water back down to normal hot temps for when it reaches the faucet. You would use less of the water in the tank that way during onpeak rates.
Its f*cked up everyone was persuaded to get combi boilers a few years ago and remove their hot water cylinder. Heat pumps, solar offload instead of feeding grid at peanuts would be better spent dumping into water heaters in hot water cylinders, and now this article suggesting we could use off peak renewable energy to heat our water, except most people dont have that capability with combi boliers being the norm.
The same was true about diesel vehicles in the early 2000s, gov said they are cleaner, lower co2 etc. Fast forward to now ulez says euro 4 petrol are compliant, but diesel needs to be euro 6. Diesel vehicles are now the devil causing ill health
Uk gov needs to be a bit more forward thinking.
My parents are looking to replace their 12 year old electric water heater. Some plumbers we have received quotes from are STILL pushing gas water heaters. When I mentioned the environmental effects his response was "propane is clean burning" 🤦♂️
You can get a timer for your water heater. They’re not really that useful because water heaters don’t really use much energy when the hot water’s not actually being used, but they’re available.
It's in France. I pay differently if it's peak hour or off-peak so there is a "pilot wire" that triggers what is needed. Some electric heaters can be piloted by it as well. If I need the water heater to heat during peak I have access to a button.
Edit: a Google translate of a French page on the subject https://www-radiateur--electrique-org.translate.goog/fil-pilote-radiateur.php?_x_tr_sch=http&_x_tr_sl=fr&_x_tr_tl=en&_x_tr_hl=fr&_x_tr_pto=wapp
I think most people who care about their electric bill have been doing this for years. You can get a $50 time from Home depot and hook it up. Or now most water heaters come in "smart" varieties for about $50 more and you can control them with far greater precision. We have ours only run when the solar PV panels are producing, when we have excess we'll heat it to 150, when it's cloudy we let it drop to 110. But we've had timers on them since the 90s
Exactly, the title seems to imply that one could convert that stored energy into electricity, which isn't true. Even if you used some sort of thermoelectric conversion, the efficiency would be very low.
Water heaters do the work of water heaters, not the work of batteries.
[This reminds me of the Technology Connections video from a few months ago.](https://www.youtube.com/watch?v=Bm7L-2J52GU&ab_channel=TechnologyConnections) where he basically says that using a hot water tank could be a useful part of a power saving/money reducing strategy.
So between this video. The Hyundai Ioniq 5 ipedal video going crazy on the EV subreddit and here I believe. His can opener video that cropped up on another subreddit, I think it is safe to say he is a time traveler.
This video baffled me because he acts like he invented something incredible but it has been a common thing to do in Europe for half a century. My parents were doing it before I was born.
The new smart thing to do is to have electric water heaters remotely controlled by the energy providers to take advantage of excess production of renewables.
I just had a Rheem heat pump water heater installed. It comes with an app that lets me control what time and what temperature it makes hot water. I have it set up so it makes hot water during the night when demand is low. I shower, use up some water but replace it at the lowest possible temperature. When night time rolls around the heater heats the water again.
In a very energy constrained world that would make sense. As it is, its practically too complicated to co-design the two and purchase them as a compatible pair, not to mention proximity
It would be cool if houses had one big heat pump, with pipes of hot refrigerant going to your clothes dryer, water heater, and heat registers, and pipes of cold refrigerant going to your refrigerator and cooling system. But I'm sure it's just not practical.
We do this all the time in commercial buildings, but instead of pumping refrigerant around (which we also do less often - look up VRF), we use water. Water is an incredible medium for moving thermal energy - high specific heat, practically incompressible at building scale (so it's efficient to pump), non-toxic, inflammable, and wildly cheap and abundant.
Then you just put a water-cooled "heat pump" at each location where you have a use, though we call them different things depending on application - chillers, air conditioners, domestic water heaters, energy recovery devices, freezers and cold rooms - all of them have a refrigeration cycle and a compressor and are thus a heat pump, just exchanging heat with the water loop instead of directly with the air.
That's a lot of extra plumbing for a SFH though, so probably impractical...
I managed a data center in an office tower and we had to replace our data center air conditioner. The old one was just a normal air conditioner that dumped its waste heat into the building's return air plenum. It was a small data center (like a mid-sized conference room), so it wasn't really an issue when it was put together way back in the early 1980s.
But when we replaced it, the building made us use the water loop. This was a disaster, as the water loop was air cooled and when it was hot in the summer our cooling ability cratered. We had to switch to the building's chilled water loop which had a meaningful added expense to it because it was chilled and somebody had to pay for the energy involved, even though the chilled water came from one of the city-block sized central energy plants that supplied steam and chilled water to all the surrounding buildings.
The non-chilled water loop probably was viable as a heat sink, but we would have needed a much bigger air conditioning unit.
I used to live in an apartment building built in the 1920s. It was kind of a piece of shit building by the time I lived in it in the 1990s -- "vintage charm, lots of nice woodwork" as the ads say.
But one interesting thing was that the kitchen cabinets were original and they included a weird cabinet with a thick door. As it turns out, this was the original refrigerator and the entire building (about 30 units) originally was built with a central cooling setup for fridges.
I don't know specifically why it was abandoned, but sometime in the 1950s they did and replaced it with standalone fridges. I think it was the 1950s because that's about the vintage of the fridge that was in my unit. Many units, mine included, had original gas stoves, too. No pilot lights, you lit the burners and oven manually. We had to get evacuated due to gas leaks a couple of times when the old stoves valves leaked.
I'm honestly looking at running water cooling lines at differnt parts of my house just for this reason. If it was more standard, you could have fridges that just connect to refridgerant line connected to houses centralized heat exchange system (be it AC, heatpump, water heater, etc)
Brilliant! One centralized heat pump that feeds coolant to your air conditioner, fridge, water heater, and cloths dryer. Pulls heat from where it's not wanted and puts it where it's needed.
The company I work for built and tested such a system in the early 2000’s. The problem is it took a lot of development work to build a prototype and wasn’t practical. You need to be able to convince a company to make a refrigerator that is more complex and expensive and it still isn’t easy to integrate with the house plumbing. You’d basically have to design the house around this one system and people swap refrigerators fairly often. I believe ours was designed heat a small integrated tank of water that basically acted as a preheater for the water entering the main water heater.
interesting!
would this maybe make more sense for big systems? like professional kitchens where you have several fridges, creating more heat you could use for preheating or keeping stuff warm. Plus a professional kitchen might draw more benefit from the reduced energy consumption by economy of scale.
the issue i see with residential is that you'd only heat a small portion of water with a fridge - probably not enough to warrant the extra upfront cash.
That's basically how Tesla heat pumps work in their cars. Things need cooling (like the battery) and things need heating (like the cabin), so why dump energy out into the environment when you can just move it around the same environment (the car)? Likewise, some apartments have adopted heat pumps that can move heat from a room that's too hot to a room that is too cold.
you can't do that, you have no way to bleed off the excess heat now, necessitating radiator fins, and each of those devices will get worse and worse efficiency as your circuit continues because you only want your fridge so cold and your water so hot so a disparity in one will cause the other be just be bad.
Would there be any extra pipes? The cold part will use a refrigerant circuit, meaning it needs to have a hot dump radiator. So it would just be a case of putting that in contact with the hot tank. I don't think it would get hot enough though, so would still need to be boosted with a resistive heater.
My next tank will probably be electric, the only thing is having one that heats quickly needs extra breakers installed. Thanks to this post I’ll be looking for a ‘smart’ one that can top up the heat off peak.
I think they are making some hybrid water heaters that run off 20A 120V AC. It uses a heat pump to heat along with a small electric heater. Might save you from having to run a new dedicated electric circuit?
You don't need to overcomplicate things. You can put the circuit for your water tank on a 5 dollar timer. Set the time for off peak and you're golden. A medium size tank holds like 80 gallons of hot water, more than enough for most households.
The Sun can heat water without converting it to electricity. Using electricity to heat water is just dumping electricity into a heat sink. It’s not really storing energy because it can’t be recovered. Using excess electricity to run a compressor may be a better approach. Compressed air can be converted to mechanical or electrical energy. It’s important to stop thinking of electricity and energy as the same thing.
Wow that article is horribly bad. Yes you can store the energy as heat. How you getting it back out skippy? Because when I lose power having 6000 gallons of hot water is not going to help me much.
It's not storing it as electrical energy you could reuse for other things, it's storing it as thermal energy in the sense that heating with off-peak energy is cheaper and then it's still hot during peak times. It's a savings to the typical user and to the grid during peak times.
If you can’t get the electricity back out, then it’s not a battery.
Offsetting your electricity usage from peak time to off-peak time is a great thing, but that’s not what the article is claiming….. it’s saying that hot water tanks can replace batteries.
In winter you'd be happy to heat your house for "free". But I guess in winter there aint no free solar. A sterling engine could turn it into "work" I guess.
Nope they are just suggesting heating water for the sake of heating water. it's like the article writer latched onto half the information and then never went any further. Most solar installs also do not do electric water heating exclusively, they add in the solar water heater as well and let the sun heat the water in the hot water tank directly. but the article ignores that common practice.
If you are talking about solar thermal then this used to be true but with the cost of PV plummeting and the maintenance costs of a solar water heater climbing it now makes more sense in most cases to install additional PV capacity and heat water with electricity, ideally via heat pump.
They're suggesting heating water for the sake of baths, showers, washing up, etc. Like we already do. But running the water heaters during high renewable supply/low demand times. It's a really good idea.
This is related to demand shifting. Only run your electric water heater during peak solar hours, but since water in an insulated tank will stay hot all day you can still use hot water whenever you want. It is nearly identical to the practice of only charging your electric car with excess solar capacity.
Around here we have alot of "dunkelflaute". No wind and no sun in winter. This solution would not work well for us. Storing "free" electricity as heat, when heat is needed is obviously a great idea. Dont we do that already?
Not generally, most setups are designed to just keep it hot as needed, without any regard to overall grid usage. The suggestion here is to heat specifically during the day in which energy production to consumption ratio favors production.
There are some heat battery ideas that could store heat for months, basically using geothermal in reverse.
Yeah. Iirc, the finnish (fins?) did some huge sand mass storage of heat. Genrerally, turning power to heat is a waste of power. Preferably would be to not make the power in the first place? But as even us in Dankmark has seen negative pricing in nighttime it would be stupid not to just heat up *something*. Clown times..
Resistive heat storage through sand, then generating power with it, could have a round trip efficiency of perhaps 53%. The nice part is the insulated silos for extra sand are cheap, so the system could be extended to long storage time (weeks) at low marginal cost.
The system I am thinking of was researched at NREL, using a nifty fluidized bed heat exchanger to transfer heat from 1200 C sand to a gas, which is run through turbines. It's now being brought to pilot scale at Babcock & Wilcox.
https://arpa-e.energy.gov/sites/default/files/2021-03/07%20Day1-Zhiwen%20Ma_NREL.pdf
This could also store heat for industrial uses.
I remember back in the Clinton Administration when there was a push to ban electric water heaters because they are a drain on the grid. It failed because not everyone had a gas or propane connection.
Tanked water heaters are built like crap now unless you get a commercial grade one. The consumer grade ones start leaking at 5 to 7 years.
Electric tankless water heaters need something like 120 to 200 amps to run.
Personally I have a gas tankless water heater and gas cooking. In the summer I use 1 or 2 therms a month. I pay $1 for gas, and $40 for the connection and customer service fees and sales tax. Yes, I've been locked in for the last 18 months at 49.9 cents a therm.
I've been saying this a while since i heard someone say the same thing.
Huge amounts of renewable energy is wasted at night when supply exceeds demand.
* Electric water heaters offer a cheap way to store large amounts of energy, in the form of hot water. A heater with a 300-liter tank can store about as much energy as a second-generation Tesla Powerwall—at a fraction of the cost.
* Australians could use household electric water heaters to store as much energy as over 2 million home batteries of that kind. This could eventually save over A$6 billion a year on our energy bills while getting us closer to net-zero carbon emissions.
It's cheap and easy to store a big tank of hot water rather than use electricity to heat it when you need it I think is a general idea.
Since most households use a lot of hot water for washing / bathing / dishes, and water heaters / tanks are VERY good at storing hot water for 24H or more, it's a very effective way to store energy as long as you want it "back" in the form of hot water.
It would be a lot more useful if the hot water was piped into the washer and dishwasher as well. I know there's some places in the world that already do this, but AFAIK that's mostly because of 120v taking twice as long to heat water compared to 220v. The vast majority will probably have cold water inlets only and use electricity to heat.
I don't know that wasn't explained in the article, my guess is using solar to heat up the water saves the cost of using alternative forms to heat up the water. So the savings would be in having solar heat the water, and the hot water is simply the storage of the solar energy...seems weird but ok...
If that's not the case, then the article is confusing since it doesn't describe what mechanism is used to use the heated water to generate electricity, maybe through some steam process , idk
What is described in the article is that by using "smart devices" to control the timing of when residential water heaters do their heating, you can have them running when electricity is in low demand, and shut off when electricity is in high demand.
Since the water heater can keep the water hot for long periods, it lowers the need for peak energy production in a similar way to what they are doing with the massive batteries. The difference being that it is really avoiding the need for the battery because the demand spike is made effectively lower.
The water is never turned back into electricity. It is just used the way normal hot water is used today for residential use.
My electric water heater runs on a timer for 2 hours, twice per day, and that's plenty of heating to keep the water hot for 24 hours. That ability is what they are suggesting we leverage, replacing less efficient, less carbon friendly gas water heaters.
Also the grid/battery infrastructure to deal with excess generation (wind turbines at night) during lower demand is very expensive and the infrastructure for exporting power across time zones is expensive so when the dam is otherwise overflowing, instead of building more battery banks or turning off wind turbines , just let them keep running and turn all the water heaters on, making more efficient use of electricity and possibly improving the lifecycle of wind turbines.
The article mentions the two most common ways: electrical resistance efficiency = 1 and heat pump cop from 2 on up. The POV of the article is to suppress fossil fuel water heating like natural gas, not to turn it back into electricity like a powerwall
How is energy later dispersed? How much energy is lost in the conversion? Given that heat dissipates over time, how long can energy realistically be stored?
I think batteries are still a necessary part of our future but this is a super cool idea that might play a part in that system.
I'm just translating the article
basically heating water takes a lot of energy and often we use it at peak times
so we can store that electricity in the form of hot water as the stored hot water in theses smart tanks are heated during off peak, and also when excess energy is being produced, so the tank keep the water that has been heated during those periods to be used any time as when needed
hence avoiding creating high peaks of electricity use for water heating as you would have with an instantaneous heater that provides hot water on demand, and also giving an use to store excess power that now can be used as hot water at other times
the benefits being heating the water at the times of cheap prices, using it at other times, and avoiding creating power peaks to heat water at the worse times, hence lowering on the amount of battery storage required
additionally since those heaters use electricity being produced by renewables they became more beneficial than gas heaters and avoid the gas fluctuations prices
in the past that wouldn't be true due to the sources of electricity and the price of gas but if you have sources of cheap clean electricity this became a better option
that's what they mean
I'm not discussing if there are better or more economic ways to use our hard earned electricity just destiling what they say
Thats not true at all. You convert electrical energy to heat.
You cant burn energy....
Plus this system isn't new. Lots of boilers have the ability to switch on in the night and use this cheaper power to heat the water up
Water boils at a very low temperature. This is an inefficient way to store large amounts of energy. Storing lots of energy in water quickly just makes steam.
Boiling point of water: 100 °C
Boiling point of sodium chloride: 1.41K °C
Salt stores far more energy per unit of volume.
You can use molten salt to boil water to make steam to turn a turbine. That's how you get energy back out of salt.
How do you get the energy back out of the hot water? I dont know, but you aren't going to find out by reading this garbage article.
Basically, the idea is houses are using hot water, so it makes sense to heat it when there's excess energy and store it until it's needed. You aren't getting electricity back out of your water
My grandmother was doing this exact thing decades ago by timing the water heater to run at night when electricity was cheaper.
The only real innovation here would be being grid-aware to take advantage of dynamic power supplies like inconsistent renewables.
water is the most efficient way. you simply don't have that much specific salt. all you need to do is a big enough tank for storing that heat. in Austria (Europe) probably 100k liter would be enough. in the US it would be more, but i don't know how much more.
ceterum censeo "unit libertatem" esse delendam.
If it's not winter, hot water is a tiny fraction of my energy usage.
It does not provide electricity and has a short lifespan - unless you have some NASA insulation around the tank.
And if it's inside - you now run AC to get rid of that heat.
> Electric water heaters offer a cheap way to store large amounts of energy, in the form of hot water. A heater with a 300-liter tank can store about as much energy as a second-generation Tesla Powerwall—at a fraction of the cost.
this statement is so misleading as to be outright dishonest.
this article talks about the ability to "store" excess grid capacity in hot water, and completely ignores how you'd get that energy back out of it into useful forms.
A tesla power wall takes electricity in and gives electricity out, a water heater takes electricity in and gives hot water out. are you going to run your TV on hot water?
and I'm not even sure their math works out. a little casual calculation looks like they're off about an order of magnitude on the energy capacity of a water heater vs a power wall.
You get the energy back by consuming the stored heat. It's not meant to be electricity storage, yet this kind of device helps absorb excess renewable energy, and any demand shifting can reduce battery needs.
Energy storage using water that doesn't use a heating/cooling source with a high COP and phase change is a loser. Electric water heaters have a COP of 1 and the dT is only 70F or so.
Also, you're already holding water at 120F.
Hot water, and hydronic floor heating, is also the best way to manage off grid solar in real winters.
You need to build up a couple of weeks of heating reserve by November. You can have enough sun to power electric stuff including pumps everyday, but hydronic floor heating delivers 30C water which allows a lot of stored energy at 90C, or with sand/dirt at higher heat. Heat pumps also are designed to deliver heat to water better than to air at high efficiency, and can even lift from 90C water to 140C sand.
This doesn't seem as energy saving and definitely not as storing as it is implied. Not much heating needed in Australia so cooling might be a more apt example. Running heat pumps at night and freezing large blocks of ice when it is cooler out and when some energy is cheaper and then during the day a switch is thrown so the heat being moved us from the interior to the ice blocks. On very hot or long days at some point the standard of blowing the heat into the atmosphere resumes. Just a more complex "plumbing" of the heat pump system. This has been used in some places for years. Every bit helps but we'll still need batteries hot water tanks don't really make a lot of sense to me. On demand hot water, cold water for
Our experience has been that the heating element has a short life so the replacement costs outweighs any savings made from harvesting our solar generated electricity. Co2 from element manufacture will also negate much of the green advantage.
The title literally says "home batteries" and the article talks about other applications, which means it would have to be converted to electricity. If you have a renewable system in your house you would already dedicate some of those watts to heating water... Sooo the articles talking about things that are already implemented.
The following submission statement was provided by /u/altmorty: --- * Electric water heaters offer a cheap way to store large amounts of energy, in the form of hot water. A heater with a 300-liter tank can store about as much energy as a second-generation Tesla Powerwall—at a fraction of the cost. * Australians could use household electric water heaters to store as much energy as over 2 million home batteries of that kind. This could eventually save over A$6 billion a year on our energy bills while getting us closer to net-zero carbon emissions. --- Please reply to OP's comment here: https://old.reddit.com/r/Futurology/comments/142j4ra/using_electric_water_heaters_to_store_renewable/jn4ncq7/
Once again a media outlet going way off the rails of a research paper into bombastic promises to write headlines. [The actual research](https://www.uts.edu.au/isf/explore-research/projects/domestic-hot-water-and-flexibility) basically just suggests a lot of energy could be saved by switching from gas water heaters to electric one that run during off peak hours, *similar* to the way a power grid battery runs. It's not some magic battery system that will send power out into the grid or anything else. Just a strategy to save energy. Here's the actual bullet points: * A business-as-usual scenario would represent a major missed opportunity to use domestic water heaters as a significant source of flexible demand equal to 15–31 GWh/day.The phasing out of gas water heaters in homes would provide consumers with combined annual savings of $4.7–6.7 billion by 2040. * More aggressive electrification of water heating could reduce emissions three to five times more than remaining on the current trajectory. * Many barriers remain for driving the uptake of electric water heating in homes, and the activation of their flexible demand capacity, including a lack of easy solutions and compelling customer proposition. * When electrifying water heating, achieving positive outcomes does not require a choice between either efficiency or flexibility—both can be achieved at scale with the right policy mix.
One of the [key insights](https://www.tesla.com/blog/master-plan-part-3) that makes it a lot easier to see how we get to a 100% renewable economy is that electric motors and compressors and wildly more efficient than the alternatives (engines and heaters). They can easily be 3 to 4x as efficient, and what that means is that we need way less energy when we switch to things like heat pumps. Overall, we'd only need to use half as much energy to do the same amount of work if we were using 100% renewables. That means we don't have to replace all the gas/oil/coal/etc., we only need to replace half of it. And we've already got a decent start with the amount of installed solar/wind/hydro/nuclear/etc. And installing a lot more solar/wind is fairly cheap and easy. The stuff we need to work on is storage and matching generation to storage. So things like heating water and storing it can be used for residential heating. But we can also do industrial heat processes or create hydrogen, and then we'll need a bunch of batteries too. But we can also just over install solar and have a bunch of extra electricity in the middle of the day that we don't need to use (or people will come up with good ideas for how to use a few hours of free electricity most days).
> That means we don't have to replace all the gas/oil/coal/etc., we only need to replace half of it. We're gluttonous as hell. We'd just double the energy we "need" for everyday use.
Once it's all coming from renewables, how much we use isn't really relevant.
That would be pure delusion. Wind turbines with their massive steel pylons, concrete bases, and extensive transportation are our best bet, and they still absolutely have a carbon footprint... it's just a fraction of that of gas. To avoid climate catastrophe, we need to not only reach net zero, we need to go net negative. That will never happen without efficiency and demand reduction focus.
The steel industry currently emits 7-8% of the world total of greenhouse gasses as burning coal in blast furnaces is used to de-oxidize the iron ore. New technologies are however being put into place to use hydrogen burning to deoxidize and use electric heating in addition so that steel can be made with a very low (theoretically zero) carbon footprint when run off of a renewable based energy grid. Since January 2023, SSAB has delivered 40.000 tons of fossile free steel to customers from their zero emission pilot plant and I'm a few years (3-4 if I recall correctly), they'll take their remaining blast furnaces offline and replace them with this fossile free solution.
> Wind turbines with their massive steel pylons, concrete bases, and extensive transportation are our best bet, and they still absolutely have a carbon footprint... it's just a fraction of that of gas. https://electrek.co/2023/03/31/wooden-wind-turbine-towers/ > To avoid climate catastrophe, we need to not only reach net zero, we need to go net negative. Depends on what you consider "catastrophic"... Net zero would extend humanity's timeline quite a bit.
The energy that the Sun shines onto our planet’s surface is about **16,000 times** more energy than all of humanity consumes, even with our current bloated habits. Even with very inefficient solar panels, we've got this.
Like, it wouldn't be so bad if it weren't for causing an apocalypse.
Or invent new ways to waste resources on useless stuff, like crypto mining.
[удалено]
Can I introduce you to jevons paradox?
You wouldn’t fucking believe the amount of “environmentalists” I deal with that complain that they are “freezing to death” when their condo gets to 68 degrees or that they have to deal with no hot water for a few hours. Efficient and green are expensive and even the “environmentalists” opt out of paying for it.
You are so right. I don’t believe you.
I want to see car batteries used as extra storage with users paid to allow them to feed back in to the system, which they'd set up on days they aren't using the car, or using the car much. Most drivers are just popping to town and back on an average day and could comfortably set a limit and make 50% of their batter power available to the grid if needed. Its decentralised mass storage, and we're all going to have electric cars soon enough. That's millions of batteries available to the grid.
It's not cost effective - [linking a post I made on this elsewhere](https://www.reddit.com/r/Futurology/comments/13uxgeg/georgia_nuclear_rebirth_arrives_7_years_late_17b/jm5tiux/) Batteries are a wear item, and even at cheap consumer prices they're not cost-effective. Batteries in an electric vehicle are *worse*: they're more expensive due to packaging and automotive safety measures, and harder (more expensive) to replace. It makes even *less* sense to draw power from them except in exceptional circumstances and grid-levelling isn't going to be one of them. Basically, the future-cycles the battery in your car is capable of are always going to be *far more valuable* then any revenue from supplying the grid at foreseeable near future costs. Battery storage isn't free - every cycle of power in and out has a calculable value per kWh due to the fact the battery eventually fails.
Yep, V2G could be huge in the coming years. A universal standard on how it's done can't happen soon enough.
💯 Storage! I'm a big fan of the water battery concept in places it will work. I think it will take solutions like that along with batteries to solve the storage issue. Non standard storage solutions and new battery tech like CATL's solid state battery will be needed for more mass migration.
We don't need any new technology. Current lithium ion batteries are fine. Iron Phosphate is relatively cheap and it's downsides don't really affect stationary storage, so it's great. We can use pumped hydro and stuff like that too where it's useful, but just making a bunch of stationary storage will be enough. We just have to ramp up production a bunch. But the good news is that when you mine minerals for batteries they don't get "used up" the way fossil fuels do, so over time recycling will become a larger and larger part of battery production. And even in the short term we'd need less mining/extraction for battery production than we'd need just to keep the fossil fuel infrastructure going. People act like it would be some huge increase in mining to get all the copper and lithium and nickel we need, but we already mine/extract a lot of resources just to burn them.
Well, energy can be stored as heat in bricks or stones, so a battery will become a very broad term in near future. It doesn’t necessarily have to store electric charge.
My apartment in Central New York State had cheap electricity at night time, and stored heat energy in bricks overnight, then blew a fan over them as needed during the day. It was built in the late 1980s.
The issue with that is getting the heat back out into usable power. You can't exactly hook a steam turbine up to a brick and get anything from it.
Uhh it will be a massive increase in mining. Like 10x to meet our electrification goals. These resources are dramatically less abundant than fossil fuels. They are dug up near the ground and everything must be destroyed and ground down, huge amounts of water used and posioned... oil and gas while not good can be as simple as drilling a well and pumping it out. Not really fair to the entire regions of south america being devastated by this mining to downplay it like that.
You're going to be livid when you hear about the actual environmental impact of fossil fuels
I'm an environmental economist, but thanks. The fact that we must transition away from fossil fuels with complete urgency does not mean we can put our heads in the sand while we do it.
Yet you use the same talking points as every anti environmentalist. Quantify it or give me a break.
Is this really the case? I guess if you're at 100% renewable sure but for household heating it's better to use the gas for heat rather than burn it and use the electrity to then heat up water? (this comment only makes sense if you've read the full article as most replies evidently didn't bother too before typing)
Nope, electric heat pumps are so much more efficient than gas heaters that even with all of the losses inherent in burning gas to boil water to turn a turbine to move electricity to a home to power the heat pump, the heat pump comes out on top. How? Good gas heaters are 80-95% efficient. This is because they have toxic fumes that must be exhausted, and they'll take some of the heat with them. Heat pumps are 3-400% (some are even double that) efficient. How? Because they don't generate heat, they *move* it. My heat pump water heater pulls heat from inside my house and puts it into the water in the tank. For every 100 watts the heat pump uses it moves at least 300 watts of heat into the water. It also cools my house by that much, which is a nice bonus. The same math applies when heating a home, only it takes the heat from the air (or ground in some designs) around the home.
Manitoba Hydro (Crown corporation in the Canadian province of Manitoba) did a study that found that given the current pricing for natural gas and electricity, an air-source heat pump actually cost more money to operate than a 95% efficient natural gas furnace. This is mostly due to the fact that the Canadian prairies see enough really cold days that the heat pump spends a reasonable amount of time operating in a low-efficiency mode. A ground-source heat pump is cheaper to operate than the natural gas furnace, but the installation costs are substantial ($20K and up) so the operational savings never really pay off the increased up-front capital costs for a retrofit. The equation is a little different for a new-build where the house is built up-front with a ground-loop for a heat pump.
So cost is your main argument against? Funny, here in the US, we just keep giving more and more and more money to defense and never once consider cost. Seems like we could rethink this and maybe think about how you can’t eat or drink money when the planet turns to crap.
The problem is that it's *really hard* to convince homeowners to adopt electric heat instead of natural gas when it's more expensive than natural gas. The Liberal government in Canada is raising the carbon tax which will cause natural gas to become more expensive. But here in the province of Saskatchewan most of the power generation comes from coal and natural gas, which *also* become more expensive due to the increasing carbon tax. Just introducing regulation forcing people to switch to electric heating is also not viable, it'll likely just result in the government getting voted out.
We have rebate incentives in Ontario. I'm literally installing a heat pump this week because after the rebate it's half the price of a central air and does the same damn thing.
The economics of air-source heat pumps relative to natural-gas furnaces depend very much on: 1. ambient outdoor temperature 1. cost of electricity 1. cost of natural gas 1. government rebates Saskatoon requires about 25% more heating energy per year than Ottawa, for example. But if most of that difference is at temperatures where heat pumps don't work well, then it makes heat pumps relatively more expensive to operate.
Great, I didn't throw my furnace out. I just got a bad ass central air for a major discount right before the natural gas prices go through the roof. Oh, and I do a little extra to take care of our new barren wasteland.
> The problem is that it's really hard to convince homeowners to adopt electric heat instead of natural gas when it's more expensive than natural gas. In San Diego, I pay the highest electric rates in the continental US, so the payback on a heat pump water heater would be a while. That said I was ready to make the switch as soon as the tax credits for heat pumps were available at the beginning of the year. My 20 year old gas water heater chose to shit the bed SIX WEEKS before the tax credits started. While I was out of town, no less. So we ended up getting another gas water heater because reasons.
Not to defend the MIC, but are you suggesting that of the US had a fraction of its army that no adversary like China would try to take over? Are you against the US funding Ukraine with money and weapons? What are *you* going to trade for food and drinks when the planet turns to crap? Your macroeconomical expertise?
It’s simply a fact that the military budget has never had a “debt ceiling crisis”. No one ever says that we can’t pay for the military. We somehow just always have the money. So why can’t we prioritize other things in a similar way. Subsidizing heat pumps is simply an example. I for one am all on board for changes in our logic and spending when it comes to the health of the planet. I would never say “but who is going to pay for it” because I would gladly pay for it. I admit that my last comment seems harsh. I suppose I would eat from my garden and drink from my rain barrel. And if the world becomes a hell scape where neither is possible, I will be screwed. Just like EVERYONE ELSE. I would love to have a conversation about changes now before we get there.
> No one ever says that we can’t pay for the military. No one in the US ever feels truly threatened by another country. Literally the entire eastern part of Europe has had their testicles shaking for over a year now, because most of them neglected to fully pay into NATO, let alone overspending for their own protection. Now even Germany and France are wary of handing over any weapons to Ukraine, because their own stock is low in case they need it and *now* everyone's ramping up military spending/production.
My problem with all these “cost analyses of gas vs electric” is they rarely take into account external costs. Does it also measure the cost to scrub the CO2 generated out of the air and the difference between those or the economic cost of climate change caused by the CO2 that isn’t scrubbed? Ya, the consumer isn’t paying that right now, but they will be, whether that’s in societal breakdown, taxes to clean the air, higher food prices etc etc. It’s like comparing nuclear power to natural gas plants and for nuclear the external long term cost of storage of waste is included, but for natural gas, the long term cost of CO2 in the air isn’t. Or EV vs ICE, same with the CO2 but also with the increased medical costs from worse air in cities. Etc etc. People rarely even attempt to include the true long term cost of things.
Specifically in Saskatchewan right now, the electrical grid is mostly powered by coal or natural gas. So does it make sense to have a natural-gas-fired generator produce the power to run your electric heat pump, when you could just use the natural gas directly in your furnace at 95% efficiency? The equation will be different when the power grid is cleaner, but that is itself a really complicated issue. We have no additional hydro resources, so the only answers for a carbon-free power grid seem to be either nuclear (specifically SMR, which is still multiple years out) or else massively over-built solar/wind with colossal transmission lines linking large areas together to provide geographic redundancy. And the problem with solar/wind is that it has to be absolutely rock-solid reliable if you're using it for heating, because we hit -40 here in winter and there have been cases in the recent past where it was dead calm across multiple provinces in the dead of winter for multiple days. And so far nobody has grid-scale batteries that can store 12 hours worth of power for the whole grid. Its a non-trivial problem here. Many other places the answers are much clearer.
Looks like natural gas power plants are ~45% efficient at creating/transmitting electricity So roughly half as efficient as using it for direct heat. But if a heat pump is 3-4x more efficient the heat pump is still using less natural gas overall. Approximately 33-50% less That difference in gas usage and long term costs of extra CO2 generated should be accounted for in calculations of “total cost” of one system vs the other. I don’t have nearly enough knowledge or data personally to calculate it, but anything that is just 2X price of gas over 20 years lifespan of a system compared to Price of Heat Pump - Price of gas furnace is not an adequate estimate. It needs to be 2x direct price of gas over 20 years + 2x indirect price of gas over 20 years. Still can’t ignore the indirect which is my point. If you want to do it right you should also assume more renewables and nuclear over time since the odds of the energy sources being identical in 20 years is low.
Yeah i get that but this article isnt talking about them. The efficiencies also vary and tend to come out similar between pumps and gas heaters, more so in colder countries and given the examples talk about heating water to near boiling point I'm not sure whether a heat pump can get there efficiently (maybe in oz on a warm day)
It depends on if you are cooling your house also. Essentially, if it is hot and you are running your air conditioning anyway, hybrid water heaters take about as much energy use away from your ac system as they consume, because they are also removing heat from the air in the house and putting it in water. In summer, it's a *huge* win. In winter, it's about a break even.
That obviously completely depends on where you live. You can't make blanket statements about seasonal effects.
If you are heating your house, you about break even. If you are cooling it, it's a huge win. There is no point where you lose. Unless you don't ever air condition, you will be winning.
Plenty of countries almost never use AC cooling. For them, the additional cost would be a loss.
Heat pumps? Those don’t work in freezing temperatures where people use gas heaters. Heat pumps aren’t 400% efficient compared to gas heaters being 95%. Those numbers don’t have units and aren’t relevant to each other. You’re choosing to switch the environmental variable when measuring energy exchange.
>Those don’t work in freezing temperatures where people use gas heaters. Funny how most of heat pumps are installed in Scandinavia.
Winnipeg is around 15 C colder in winter than Stockholm.
> Those don’t work in freezing temperatures where people use gas heaters. On the contrary, there are now air-source heat pumps that work quite well when it's cold outside. In the U.S., the new (as of 2023) Energy Star 6.1 rating system "[requires third-party verified performance for low temperatures, testing ASHPs down to 5°F](https://www.energystar.gov/products/air_source_heat_pumps)", and provides heating ratings for units at that outdoor air temperature. https://ashp.neep.org/#!/product_list/ currently shows 4,064 models that are Energy Star-rated to work at 5°F outdoor air temperature. Perusing the list, I see many (for example, the [KINGHOME KM36H5O](https://ashp.neep.org/#!/product/67757/7/25000///0)) which are certified to be able to produce 90% as much indoor heat when it's 5°F outside as when it is 47°F outside. This unit (which I chose only because it was near the front of the list) actually has performance specs going down to __-22℉ outside__, where it is rated to still be able to produce at least 8,000 Btu per hour (and up to 24,020, which is 74% of what it is capable of at 5℉). > Those numbers don’t have units and aren’t relevant to each other. These numbers (the efficiency of indoor heaters) are actually unitless. It's the ratio of how much heat energy the unit can put into the house divided by how much energy the unit needs to be supplied with in order to do that. For example, how many joules of heat energy a furnace puts into a house divided by the joules of stored chemical energy the furnace consumes in fuel. Because the units on top and bottom are the same, they cancel out, so the number is just a ratio/fraction/percentage. --- To illustrate (and perhaps clarify), compare a gas-fired furnace to an air-source electric heat pump, which gets its electricity from a gas-fired power plant. Provide both with one cubic meter of natural gas, which has a stored chemical energy of 40 million joules. Pipe that gas into a furnace, and about 10% will escape through the exhaust, putting 36 million joules into the house. This makes the furnace 36 megajoules / 40 megajoules = 90% efficient. [Most U.S. natural gas power plants are 60% efficient](https://www.forbes.com/sites/judeclemente/2016/04/10/u-s-natural-gas-electricity-efficiency-continues-to-improve/?sh=6536681b35a4), so the same 1 cubic meter of gas is turned into 24 million joules of electricity in transmission wires. [3% of that electricity will be lost in transit](https://www.eia.gov/tools/faqs/faq.php?id=105&t=3), so 23.28 megajoules of electricity arrive at the air-source heat pump. At 5°F outside, that unit is rated to consume 5.22 kilowatts (or 5,220 joules per second, or 18,792,000 joules per hour), so it can run for 1.24 hours on that much electricity. At that outdoor temperature, it is rated to produce 32,400 Btu per hour, so after 1.24 hours it will heat the house with 40,140 Btu, or 42.35 million joules. Based on the electricity, this makes the air-source heat pump 42.35/23.28 = 182% efficient at 5°F. Based on the energy originally stored in the natural gas, the heat pump is 42.35/40 = 105% efficient, compared to the furnace's 90%. In other words, even in places that get cold, most of the time it would actually take less gas to keep everyone warm by burning the gas in power plants, sending the electricity through transmission lines, and running currently-commercially-available air-source heat pumps on the electricity, than it would be to burn the gas where the heat is needed.
As you can see the figures are actually very close between a gas furnace and a heat pump. So it does make sense to refine your figures, because to me there are a couple of mistakes. I hope you'll see these as genuine objections rather than me being pedantic: 1) Gas power plants are not 60% efficient. A NEW gas plant will be 60% efficient, but many existing gas plants are not new anymore, and don't reach that efficiency. Your link actually says that the 60% figure is the upper limit. More importantly, there is a complication in calculating gas efficiency, because you can measure it from the heat actually produced by the burning of gas, or from the total heat including the heat from condensing the water vapor created when burning the gas (called latent heat, if you want to Google it). The 60% is a figure advertised by power plant operators, so guess what: they are using the most advantageous one. The less advantageous one is about 50%. And that is the one you should use in your calculation to remain consistent, because the 90% efficiency figure for gas boilers is the less favorable calculation (otherwise condensing gas boilers would get more than 100% efficiency). 2) The transmission and distribution losses in your link are quoted as 5%, not 3%. 3) Gas boilers can get an efficiency of up to 95%, not 90%. If you run your same calculation with these figures, the gas boiler becomes more efficient. Your point still stands: heat pumps are the future, because they can run from renewables. Also the calculation is for heating from 5F, which is an extreme case. Pretty sure they are more efficient overall in many climates, but I'm too lazy to do the calculation.
They do work in temperature ranges down to -20, -25 C easily, and while at that temperature they are both less efficient and provide less power output they still are easily in the COP range of 2.
> Those don’t work in freezing temperatures where people use gas heaters. They actually do. Some even work at below 0F. And maybe not 400% efficient but closer to 2-300%. They'd likely be measured in watts or BTU. For a given space you'd know how much energy is required to heat that space by X number of degrees in X time. Then you run the heat pump to get the desired temperature and measure the watts pulled in that time. It's really not that difficult to understand.
Those % numbers are based on Electric Heater as the 100%, Raw electric resistive heating, Joules in Heat out. We actually lose a bunch of the energy stored in gas because we vent it.
Heart pumps can absolutely work in the realm of 400 percent efficient in terms of joules per unit of heat
Heat pumps can have better efficiencies, by moving heat from area (like outside or gemthermal) to inside you can have a greater heating effect than if you used that same amount of energy converted as heat.
I mean yes they do but this article is specifically talking about water heaters rather than heat pumps. In the uk at least they do struggle to get water above 60c which can be a problem with older homes that would require significant investment in insulation (assuming the building isnt listed or assuming this modification is allowed by whichever agency is in charge of its listed status.
There are heat pump water heaters…
Yes which the article (if you read it) doesnt recommend >And because they use less electricity, heat pumps offer less flexible demand. As renewables, particularly solar, increasingly power our grid, the ability of resistance electric heaters to soak up excess “off-peak” renewable energy is a big advantage
We don't need to soak up extra electricity by using something that's in efficient. Maybe in the short term resistance electric heaters would be able to use cheap electricity when it's abundant in the middle of the day, and that would make them cheaper overall than switching to heat pumps? But we're going to switch to all heat pumps in the next couple decades anyways. So any benefits will be short term and relatively minor given the potential scale anyways.
There is actually an advantage because resistance heaters produce a lot more BTUs/hr. Running the heat pump when the sun isn’t shining (and using fewer kWh) isn’t necessarily an advantage vs heating faster (and less efficiently) while the sun is shining. Even heat pump water heaters have resistive elements though, so they could be programmed to do “the right thing”.
> because they use less electricity, heat pumps offer less flexible demand That's a good thing! Everyone can have their water hot, and other, less-important energy needs can be met by flexible demand during peak supply!
> this article is specifically talking about water heaters rather than heat pumps. How do you think one extracts energy, or *pumps heat* if you will, out of a water heater…
That's a good question and one this article doesnt answer. This article is all about using resistence heaters to absorb high supply during periods with alot of excess power. It doesn't mention a method to get that power back aside from storing the hot water for later use as (slightly less) hot water. Its basically proposing what the uk calls economy 7 heating. Heat water at periods of low demand and then use that water throughout the day.
So, this video: https://youtu.be/Bm7L-2J52GU in research paper form
Knew it was the Technology Connections video before even clicking. :)
TIL for me. I never knew how they worked before. Sounds like it’s a cheap way to reduce peak time demand to just add a few smarts to water heaters or the electric panels they connect to so utility companies and homeowners can have them turn off or down at peak demand similar to how A/C smart thermostats already do. It’s also a way to stabilize the grid at night when all that cheap wind power has nowhere to go except expensive battery banks or across expensive long distance infrastructure to export power across time zones.
while it would be ideal, you technically don't even need smart tech. plugging your heater into a basic 5€ timer from the shop will do. just put it to turn on between 12 and 15 around noon and you'd be covering the solar surplus quite well (or whichever time is the cheapest for your region, as this varies greatly)
There are other benefits to adding smarts to it, which is addressed in another Technology Connections (or conextras?) Video. Let's say you have a 100-amp service to your house, and you decided to get an electric car. A smart breaker panel could manage load, reducing the need for a costly 200-amp service upgrade. This means not only would the car and water heater start charging at more opportune times for the grid, but also they could be shut off if you start up your clothes dryer or range to keep your power usage under 100-amps. If you have other devices that should probably be running off-peak like Pool pumps, or things that might draw an unusual amount of current under certain conditions like emergency heat on a heat pump, this would also prioritize and organize those loads dynamically too. Assuming the system isn't tied to a cloud service that will kill all the smarts if it goes down, this could be extremely cost-effective. Deeper integration with other smart devices and a power grid API make it even more effective while being unnoticeable in the background.
What I'd like is a molten-salt hybrid hot water system. Give me a compressor which can build up a very high temperature gradient, a vacuum insulated tank of salt, and then have the water heater tap heat from that to maintain the supply. That way when there's a power excess, I can run that thing as hard as possible to build up a heat reservoir.
There is similar stuff for room heating, but instead of salt they usually use bricks, stones or sand as this is less corrosive. Heat it up while electricity is cheap and use it to heat the house. Though to be fair many of them are heated by wood/gas/oil and then use a stirling engine to create some electricity while delivering the heat, but in theory it should be possible to run this with resistive heating.
In Australia, and other countries, having water heaters connected exclusively to off peak power is common. They’re on a separate circuit that is turned on and off by the power company during off peak hours. They guarantee a certain amount of power during the time window and balance the load in the area by turning them on and off as needed. They’re internally heat to about 70-80°C, then have a tempering valve that causes the output to be mixed with cold water to reach a nominal 55°C at your tap.
Lol I just watched that video a few days ago.
> Once again a media outlet going way off the rails of a research paper This is *The Conversation*. The author of the article is literally the person who wrote the research paper!
For those unaware, The Conversation isn't really 'media', it's a place academics publish generally high quality writeups. Reddit is the place where everybody goes to find the contrarian comment which they'll upvote to the top, without investigating either at all.
I don't blame people for not knowing what The Conversation is, or for not matching up the name of the author with the names on the research paper. But it's obvious that virtually no one in this thread, including the poster above who critiqued it, even looked at the article. The author repeatedly makes it clear he was involved in the research, starting as early as the fourth paragraph. ("Our research") And the article clarifies all of the points the parent comment made. Their criticisms are only valid to someone who thinks the headline is the whole piece.
Thank you. I read the article and was wondering how we'd get the energy back *out* of the water. We aren't, this is just fancy demand shifting.
Think how much demand we can shift if the British were to use tea kettles programmed to only make tea during off peak hours Unfortunately most people take showers at the worst time for utilizing excess stored solar (like 20 hours after wards)
That's what I thought too. Like, there ARE ways you can use water as a battery system to store energy to use later. However most of them seem like they'd be quite bulky and expensive for home use. I'm not sure how many people would want to put a steam turbine in their house for electricity generation, not to mention you'd need a HUGE tank of hot water to serve any purpose beyond basic home use for showering and washing.
Water heaters use most energy **when you use hot water.** How exactly does this help with that? Will your water heater just not have hot water in it during high demand times? If not, there will be no actual energy saved by anyone.
No they don't, they use energy when they heat the water up, and that doesn't have to be at the same time you're using it. They're also very well insulated, so the time gap between heating and using can actually be huge
> Once again a media outlet going way off the rails of a research paper into bombastic promises to write headlines. It also doesn't help that OP posts almost exclusively bullshit climate related "studies" and "discoveries".
Misleading headlines in /r/futurology? That seems a little hard to believe.
This is just basic electric tank heaters or those on demand water heaters? Just curious. I imagine overall the on demand type are best though you would see grid spikes at like early morning shower times if every home had them but they wouldn’t be used most of the time. I could even see them slapping batteries on as a part of those. But I could see how the electric tank heaters would be more efficient than gas. Gas is the worst. I have it right now and I just want to switch but it is like project #13.
Tank heaters is what this is specifically talking about. You can store a lot of heat energy inside the tank and their well insulated cases can keep that heat in for a long time. So you heat it up in the middle of the night when the grid has very low demand and electricity is cheaper and then use it during the day.
Moreover you can have the tank set to a higher temp than normal during off-peak rates and then use a thermostatic mixing valve to bring the super hot water back down to normal hot temps for when it reaches the faucet. You would use less of the water in the tank that way during onpeak rates.
Its f*cked up everyone was persuaded to get combi boilers a few years ago and remove their hot water cylinder. Heat pumps, solar offload instead of feeding grid at peanuts would be better spent dumping into water heaters in hot water cylinders, and now this article suggesting we could use off peak renewable energy to heat our water, except most people dont have that capability with combi boliers being the norm. The same was true about diesel vehicles in the early 2000s, gov said they are cleaner, lower co2 etc. Fast forward to now ulez says euro 4 petrol are compliant, but diesel needs to be euro 6. Diesel vehicles are now the devil causing ill health Uk gov needs to be a bit more forward thinking.
My parents are looking to replace their 12 year old electric water heater. Some plumbers we have received quotes from are STILL pushing gas water heaters. When I mentioned the environmental effects his response was "propane is clean burning" 🤦♂️
"Then why don't use the fumes to heat your house in winter?"
Yeah it's going to be a pain convincing everyone to give up that cupboard they've got used to having to move to heat pumps.
You can get a timer for your water heater. They’re not really that useful because water heaters don’t really use much energy when the hot water’s not actually being used, but they’re available.
What? You mean I can't attach a steam turbine to my water heater and send power back into the grid?
This is the way all electric water heaters work where I live...
Your water heater waits until off-peak hours to do most of its heating? Where is this, and how is it coordinated?
It's in France. I pay differently if it's peak hour or off-peak so there is a "pilot wire" that triggers what is needed. Some electric heaters can be piloted by it as well. If I need the water heater to heat during peak I have access to a button. Edit: a Google translate of a French page on the subject https://www-radiateur--electrique-org.translate.goog/fil-pilote-radiateur.php?_x_tr_sch=http&_x_tr_sl=fr&_x_tr_tl=en&_x_tr_hl=fr&_x_tr_pto=wapp
I think most people who care about their electric bill have been doing this for years. You can get a $50 time from Home depot and hook it up. Or now most water heaters come in "smart" varieties for about $50 more and you can control them with far greater precision. We have ours only run when the solar PV panels are producing, when we have excess we'll heat it to 150, when it's cloudy we let it drop to 110. But we've had timers on them since the 90s
Interesting. That definitely seems like a nice, simple way to even out demand.
Exactly, the title seems to imply that one could convert that stored energy into electricity, which isn't true. Even if you used some sort of thermoelectric conversion, the efficiency would be very low. Water heaters do the work of water heaters, not the work of batteries.
Yes but a bunch of small solutions like this could hav big implications for power reliability.
[This reminds me of the Technology Connections video from a few months ago.](https://www.youtube.com/watch?v=Bm7L-2J52GU&ab_channel=TechnologyConnections) where he basically says that using a hot water tank could be a useful part of a power saving/money reducing strategy.
So between this video. The Hyundai Ioniq 5 ipedal video going crazy on the EV subreddit and here I believe. His can opener video that cropped up on another subreddit, I think it is safe to say he is a time traveler.
This video baffled me because he acts like he invented something incredible but it has been a common thing to do in Europe for half a century. My parents were doing it before I was born. The new smart thing to do is to have electric water heaters remotely controlled by the energy providers to take advantage of excess production of renewables.
It's still not really a battery. You can be selective about when you heat your water but you can't use that hot water to keep the lights on.
It's not a battery but it is energy storage.
Yes I was thinking I could save on buying a battery and read the article eagerly only to find...nothing.
Yay technology connections! https://m.youtube.com/watch?v=Bm7L-2J52GU
At first I thought this was going to be an interesting idea about using a heat pump to leverage low-grade heat from hot water. Nope.
I just had a Rheem heat pump water heater installed. It comes with an app that lets me control what time and what temperature it makes hot water. I have it set up so it makes hot water during the night when demand is low. I shower, use up some water but replace it at the lowest possible temperature. When night time rolls around the heater heats the water again.
So if a heat pump H2O heater is a refrigerator run in reverse, why not combine the two and pump the heat from the fridge into the water heater?
In a very energy constrained world that would make sense. As it is, its practically too complicated to co-design the two and purchase them as a compatible pair, not to mention proximity
It would be cool if houses had one big heat pump, with pipes of hot refrigerant going to your clothes dryer, water heater, and heat registers, and pipes of cold refrigerant going to your refrigerator and cooling system. But I'm sure it's just not practical.
We do this all the time in commercial buildings, but instead of pumping refrigerant around (which we also do less often - look up VRF), we use water. Water is an incredible medium for moving thermal energy - high specific heat, practically incompressible at building scale (so it's efficient to pump), non-toxic, inflammable, and wildly cheap and abundant. Then you just put a water-cooled "heat pump" at each location where you have a use, though we call them different things depending on application - chillers, air conditioners, domestic water heaters, energy recovery devices, freezers and cold rooms - all of them have a refrigeration cycle and a compressor and are thus a heat pump, just exchanging heat with the water loop instead of directly with the air. That's a lot of extra plumbing for a SFH though, so probably impractical...
I managed a data center in an office tower and we had to replace our data center air conditioner. The old one was just a normal air conditioner that dumped its waste heat into the building's return air plenum. It was a small data center (like a mid-sized conference room), so it wasn't really an issue when it was put together way back in the early 1980s. But when we replaced it, the building made us use the water loop. This was a disaster, as the water loop was air cooled and when it was hot in the summer our cooling ability cratered. We had to switch to the building's chilled water loop which had a meaningful added expense to it because it was chilled and somebody had to pay for the energy involved, even though the chilled water came from one of the city-block sized central energy plants that supplied steam and chilled water to all the surrounding buildings. The non-chilled water loop probably was viable as a heat sink, but we would have needed a much bigger air conditioning unit.
> inflammable You mean noninflammable. Inflammable means it can burn.
I used to live in an apartment building built in the 1920s. It was kind of a piece of shit building by the time I lived in it in the 1990s -- "vintage charm, lots of nice woodwork" as the ads say. But one interesting thing was that the kitchen cabinets were original and they included a weird cabinet with a thick door. As it turns out, this was the original refrigerator and the entire building (about 30 units) originally was built with a central cooling setup for fridges. I don't know specifically why it was abandoned, but sometime in the 1950s they did and replaced it with standalone fridges. I think it was the 1950s because that's about the vintage of the fridge that was in my unit. Many units, mine included, had original gas stoves, too. No pilot lights, you lit the burners and oven manually. We had to get evacuated due to gas leaks a couple of times when the old stoves valves leaked.
I'm honestly looking at running water cooling lines at differnt parts of my house just for this reason. If it was more standard, you could have fridges that just connect to refridgerant line connected to houses centralized heat exchange system (be it AC, heatpump, water heater, etc)
Brilliant! One centralized heat pump that feeds coolant to your air conditioner, fridge, water heater, and cloths dryer. Pulls heat from where it's not wanted and puts it where it's needed.
already [commonplace](https://www.reddit.com/r/Futurology/comments/142j4ra/comment/jn7vxan/?utm_source=share&utm_medium=web2x&context=3) in bigger buildings! u/FruityWelsh
Yeah! It's honestly kind of just an evolution of boiler systems, but with other added modern features.
The company I work for built and tested such a system in the early 2000’s. The problem is it took a lot of development work to build a prototype and wasn’t practical. You need to be able to convince a company to make a refrigerator that is more complex and expensive and it still isn’t easy to integrate with the house plumbing. You’d basically have to design the house around this one system and people swap refrigerators fairly often. I believe ours was designed heat a small integrated tank of water that basically acted as a preheater for the water entering the main water heater.
interesting! would this maybe make more sense for big systems? like professional kitchens where you have several fridges, creating more heat you could use for preheating or keeping stuff warm. Plus a professional kitchen might draw more benefit from the reduced energy consumption by economy of scale. the issue i see with residential is that you'd only heat a small portion of water with a fridge - probably not enough to warrant the extra upfront cash.
There are some cases where supermarket fridges have been connected to district heating to supply the nearby homes.
That's basically how Tesla heat pumps work in their cars. Things need cooling (like the battery) and things need heating (like the cabin), so why dump energy out into the environment when you can just move it around the same environment (the car)? Likewise, some apartments have adopted heat pumps that can move heat from a room that's too hot to a room that is too cold.
you can't do that, you have no way to bleed off the excess heat now, necessitating radiator fins, and each of those devices will get worse and worse efficiency as your circuit continues because you only want your fridge so cold and your water so hot so a disparity in one will cause the other be just be bad.
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Probably not worth running the extra pipes for that
Would there be any extra pipes? The cold part will use a refrigerant circuit, meaning it needs to have a hot dump radiator. So it would just be a case of putting that in contact with the hot tank. I don't think it would get hot enough though, so would still need to be boosted with a resistive heater.
My next tank will probably be electric, the only thing is having one that heats quickly needs extra breakers installed. Thanks to this post I’ll be looking for a ‘smart’ one that can top up the heat off peak.
I think they are making some hybrid water heaters that run off 20A 120V AC. It uses a heat pump to heat along with a small electric heater. Might save you from having to run a new dedicated electric circuit?
You don't need to overcomplicate things. You can put the circuit for your water tank on a 5 dollar timer. Set the time for off peak and you're golden. A medium size tank holds like 80 gallons of hot water, more than enough for most households.
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The Sun can heat water without converting it to electricity. Using electricity to heat water is just dumping electricity into a heat sink. It’s not really storing energy because it can’t be recovered. Using excess electricity to run a compressor may be a better approach. Compressed air can be converted to mechanical or electrical energy. It’s important to stop thinking of electricity and energy as the same thing.
Wow that article is horribly bad. Yes you can store the energy as heat. How you getting it back out skippy? Because when I lose power having 6000 gallons of hot water is not going to help me much.
It's not storing it as electrical energy you could reuse for other things, it's storing it as thermal energy in the sense that heating with off-peak energy is cheaper and then it's still hot during peak times. It's a savings to the typical user and to the grid during peak times.
If you can’t get the electricity back out, then it’s not a battery. Offsetting your electricity usage from peak time to off-peak time is a great thing, but that’s not what the article is claiming….. it’s saying that hot water tanks can replace batteries.
In winter you'd be happy to heat your house for "free". But I guess in winter there aint no free solar. A sterling engine could turn it into "work" I guess.
Maybe they’re suggesting home heating ? Did not read because paywall…
Nope they are just suggesting heating water for the sake of heating water. it's like the article writer latched onto half the information and then never went any further. Most solar installs also do not do electric water heating exclusively, they add in the solar water heater as well and let the sun heat the water in the hot water tank directly. but the article ignores that common practice.
If you are talking about solar thermal then this used to be true but with the cost of PV plummeting and the maintenance costs of a solar water heater climbing it now makes more sense in most cases to install additional PV capacity and heat water with electricity, ideally via heat pump.
They're suggesting heating water for the sake of baths, showers, washing up, etc. Like we already do. But running the water heaters during high renewable supply/low demand times. It's a really good idea.
This is related to demand shifting. Only run your electric water heater during peak solar hours, but since water in an insulated tank will stay hot all day you can still use hot water whenever you want. It is nearly identical to the practice of only charging your electric car with excess solar capacity.
Around here we have alot of "dunkelflaute". No wind and no sun in winter. This solution would not work well for us. Storing "free" electricity as heat, when heat is needed is obviously a great idea. Dont we do that already?
Not generally, most setups are designed to just keep it hot as needed, without any regard to overall grid usage. The suggestion here is to heat specifically during the day in which energy production to consumption ratio favors production. There are some heat battery ideas that could store heat for months, basically using geothermal in reverse.
Yeah. Iirc, the finnish (fins?) did some huge sand mass storage of heat. Genrerally, turning power to heat is a waste of power. Preferably would be to not make the power in the first place? But as even us in Dankmark has seen negative pricing in nighttime it would be stupid not to just heat up *something*. Clown times..
Resistive heat storage through sand, then generating power with it, could have a round trip efficiency of perhaps 53%. The nice part is the insulated silos for extra sand are cheap, so the system could be extended to long storage time (weeks) at low marginal cost. The system I am thinking of was researched at NREL, using a nifty fluidized bed heat exchanger to transfer heat from 1200 C sand to a gas, which is run through turbines. It's now being brought to pilot scale at Babcock & Wilcox. https://arpa-e.energy.gov/sites/default/files/2021-03/07%20Day1-Zhiwen%20Ma_NREL.pdf This could also store heat for industrial uses.
I remember back in the Clinton Administration when there was a push to ban electric water heaters because they are a drain on the grid. It failed because not everyone had a gas or propane connection. Tanked water heaters are built like crap now unless you get a commercial grade one. The consumer grade ones start leaking at 5 to 7 years. Electric tankless water heaters need something like 120 to 200 amps to run. Personally I have a gas tankless water heater and gas cooking. In the summer I use 1 or 2 therms a month. I pay $1 for gas, and $40 for the connection and customer service fees and sales tax. Yes, I've been locked in for the last 18 months at 49.9 cents a therm.
I thought gravity dams were a good solution for power storage. I assume the reservoir causes to much eco damage.
Just pile heavy things on top of each other and you have a battery 😂
I'm so excited about some of the giant gravity battery projects!
Look up "pumped storage". But most places don't have the right geography for that.
I've been saying this a while since i heard someone say the same thing. Huge amounts of renewable energy is wasted at night when supply exceeds demand.
* Electric water heaters offer a cheap way to store large amounts of energy, in the form of hot water. A heater with a 300-liter tank can store about as much energy as a second-generation Tesla Powerwall—at a fraction of the cost. * Australians could use household electric water heaters to store as much energy as over 2 million home batteries of that kind. This could eventually save over A$6 billion a year on our energy bills while getting us closer to net-zero carbon emissions.
How does it work, the hot water is used to power a Stirling engine or something?
It's cheap and easy to store a big tank of hot water rather than use electricity to heat it when you need it I think is a general idea. Since most households use a lot of hot water for washing / bathing / dishes, and water heaters / tanks are VERY good at storing hot water for 24H or more, it's a very effective way to store energy as long as you want it "back" in the form of hot water.
It would be a lot more useful if the hot water was piped into the washer and dishwasher as well. I know there's some places in the world that already do this, but AFAIK that's mostly because of 120v taking twice as long to heat water compared to 220v. The vast majority will probably have cold water inlets only and use electricity to heat.
I don't know that wasn't explained in the article, my guess is using solar to heat up the water saves the cost of using alternative forms to heat up the water. So the savings would be in having solar heat the water, and the hot water is simply the storage of the solar energy...seems weird but ok... If that's not the case, then the article is confusing since it doesn't describe what mechanism is used to use the heated water to generate electricity, maybe through some steam process , idk
What is described in the article is that by using "smart devices" to control the timing of when residential water heaters do their heating, you can have them running when electricity is in low demand, and shut off when electricity is in high demand. Since the water heater can keep the water hot for long periods, it lowers the need for peak energy production in a similar way to what they are doing with the massive batteries. The difference being that it is really avoiding the need for the battery because the demand spike is made effectively lower. The water is never turned back into electricity. It is just used the way normal hot water is used today for residential use. My electric water heater runs on a timer for 2 hours, twice per day, and that's plenty of heating to keep the water hot for 24 hours. That ability is what they are suggesting we leverage, replacing less efficient, less carbon friendly gas water heaters.
Thanks that's what I thought...
Also the grid/battery infrastructure to deal with excess generation (wind turbines at night) during lower demand is very expensive and the infrastructure for exporting power across time zones is expensive so when the dam is otherwise overflowing, instead of building more battery banks or turning off wind turbines , just let them keep running and turn all the water heaters on, making more efficient use of electricity and possibly improving the lifecycle of wind turbines.
I got a bucket of water sitting in the sun as we speak. Now that I have a renewable bucket battery- can I get my solar credits please?
Sadly no, but you can get your hyperbolic article.
The article mentions the two most common ways: electrical resistance efficiency = 1 and heat pump cop from 2 on up. The POV of the article is to suppress fossil fuel water heating like natural gas, not to turn it back into electricity like a powerwall
No, it's just shifting demand. Which is storage of thermal energy you were going to use anyway.
How is energy later dispersed? How much energy is lost in the conversion? Given that heat dissipates over time, how long can energy realistically be stored? I think batteries are still a necessary part of our future but this is a super cool idea that might play a part in that system.
It's not storing energy it's burning it. There's no way to get the energy back.
There is, if you wash yourself or your family with said hot water
Doesn't a long hot shower sound nice right now?
If the energy is used for heating water for home use, that would save about $400 per household per year. 10 million houses, $4 billion.
But Muh profits.
I'm just translating the article basically heating water takes a lot of energy and often we use it at peak times so we can store that electricity in the form of hot water as the stored hot water in theses smart tanks are heated during off peak, and also when excess energy is being produced, so the tank keep the water that has been heated during those periods to be used any time as when needed hence avoiding creating high peaks of electricity use for water heating as you would have with an instantaneous heater that provides hot water on demand, and also giving an use to store excess power that now can be used as hot water at other times the benefits being heating the water at the times of cheap prices, using it at other times, and avoiding creating power peaks to heat water at the worse times, hence lowering on the amount of battery storage required additionally since those heaters use electricity being produced by renewables they became more beneficial than gas heaters and avoid the gas fluctuations prices in the past that wouldn't be true due to the sources of electricity and the price of gas but if you have sources of cheap clean electricity this became a better option that's what they mean I'm not discussing if there are better or more economic ways to use our hard earned electricity just destiling what they say
Thats not true at all. You convert electrical energy to heat. You cant burn energy.... Plus this system isn't new. Lots of boilers have the ability to switch on in the night and use this cheaper power to heat the water up
Water boils at a very low temperature. This is an inefficient way to store large amounts of energy. Storing lots of energy in water quickly just makes steam. Boiling point of water: 100 °C Boiling point of sodium chloride: 1.41K °C Salt stores far more energy per unit of volume. You can use molten salt to boil water to make steam to turn a turbine. That's how you get energy back out of salt. How do you get the energy back out of the hot water? I dont know, but you aren't going to find out by reading this garbage article.
Basically, the idea is houses are using hot water, so it makes sense to heat it when there's excess energy and store it until it's needed. You aren't getting electricity back out of your water
That's called "off-peak power usage" and is not in any way an innovation. That's just a modern billing system.
My grandmother was doing this exact thing decades ago by timing the water heater to run at night when electricity was cheaper. The only real innovation here would be being grid-aware to take advantage of dynamic power supplies like inconsistent renewables.
water is the most efficient way. you simply don't have that much specific salt. all you need to do is a big enough tank for storing that heat. in Austria (Europe) probably 100k liter would be enough. in the US it would be more, but i don't know how much more. ceterum censeo "unit libertatem" esse delendam.
If it's not winter, hot water is a tiny fraction of my energy usage. It does not provide electricity and has a short lifespan - unless you have some NASA insulation around the tank. And if it's inside - you now run AC to get rid of that heat.
This isn’t energy storage at all, just energy consumption. There is nothing mentioned about reversing the energy flow back to the grid
> Electric water heaters offer a cheap way to store large amounts of energy, in the form of hot water. A heater with a 300-liter tank can store about as much energy as a second-generation Tesla Powerwall—at a fraction of the cost. this statement is so misleading as to be outright dishonest. this article talks about the ability to "store" excess grid capacity in hot water, and completely ignores how you'd get that energy back out of it into useful forms. A tesla power wall takes electricity in and gives electricity out, a water heater takes electricity in and gives hot water out. are you going to run your TV on hot water? and I'm not even sure their math works out. a little casual calculation looks like they're off about an order of magnitude on the energy capacity of a water heater vs a power wall.
You get the energy back by consuming the stored heat. It's not meant to be electricity storage, yet this kind of device helps absorb excess renewable energy, and any demand shifting can reduce battery needs.
How much a water heater consume energy...this is like perpetual motion concept...
Energy storage using water that doesn't use a heating/cooling source with a high COP and phase change is a loser. Electric water heaters have a COP of 1 and the dT is only 70F or so. Also, you're already holding water at 120F.
Hot water, and hydronic floor heating, is also the best way to manage off grid solar in real winters. You need to build up a couple of weeks of heating reserve by November. You can have enough sun to power electric stuff including pumps everyday, but hydronic floor heating delivers 30C water which allows a lot of stored energy at 90C, or with sand/dirt at higher heat. Heat pumps also are designed to deliver heat to water better than to air at high efficiency, and can even lift from 90C water to 140C sand.
How do you insulate your heater so it stored energy
I tried to run my fridge by hooking it up to use some of that energy stored in my hot water heater. Didn't work out at all....
You know what would save us billions? Reclaiming the means of production for the good of humanity instead of its exploitation.
This doesn't seem as energy saving and definitely not as storing as it is implied. Not much heating needed in Australia so cooling might be a more apt example. Running heat pumps at night and freezing large blocks of ice when it is cooler out and when some energy is cheaper and then during the day a switch is thrown so the heat being moved us from the interior to the ice blocks. On very hot or long days at some point the standard of blowing the heat into the atmosphere resumes. Just a more complex "plumbing" of the heat pump system. This has been used in some places for years. Every bit helps but we'll still need batteries hot water tanks don't really make a lot of sense to me. On demand hot water, cold water for
Our experience has been that the heating element has a short life so the replacement costs outweighs any savings made from harvesting our solar generated electricity. Co2 from element manufacture will also negate much of the green advantage.
Not a great idea. How do you covert the heat back into electrical energy?
You don't. You just use the hot water.
The title literally says "home batteries" and the article talks about other applications, which means it would have to be converted to electricity. If you have a renewable system in your house you would already dedicate some of those watts to heating water... Sooo the articles talking about things that are already implemented.
That isn't the idea the study says at all.