Pretty soon, heat pumps will be able to store and distribute heat as needed

https://www.sintef.no/en/latest-news/2026/pretty-soon-heat-pumps-will-be-able-to-store-and-distribute-heat-as-needed/

by PaulHoule • 6 months ago

268 239 6 months ago

rekabis4• 6 months ago

I would love to see a bus-sized version for year-long temperature moderation. Like, drop house heat into it during the summer so it can re-heat the house over the winter, and pull all the heat out of it by Spring so that it can cool the house over the summer.

Bus sized because that amount of thermal mass is bound to take up a lot of space, but capable of being buried so that it doesn’t actually take up property space.

syntaxing3• 6 months ago

So…geothermal? I wish this was possible too but I don’t see how it will work scientifically. Water is one of the chemicals that have one of the highest thermal mass/specific heat (maybe 1/3 of salt hydrates). Even then, you have to bury a crapton of water underground. This design mentioned in the article is more for short term, like 12 hours storage (since they’re accommodating for solar in nighttime)

Neywiny2• 6 months ago

Is geothermal not the opposite of that? My understanding was that the geothermal MO is that there's virtually infinite thermal mass in the earth so it won't heat/cool, not that you heat/cool your local chunk

rekabis4• 6 months ago

Geothermal needs either a horrifically expensive vertical bore hole going down a few hundred metres, or a good acre of land for laid-down piping. I have neither the money nor the horizontal space. So I am thinking something compact that needs to go only about 6-10m vertically into the ground (so I can hide it fully underground with about a metre of soil on top), and take up the horizontal space of 4 parked cars. I have more than enough room and cash to have that cube of space dug out.

And being on an alluvial plain, if I filter out all the rocks larger than a pea, a good 90+% of what is dug out can immediately be trucked away.

stubish• 6 months ago

You seem to be describing ground sourced heat pumps. If you wanted, you could insulate a a chunk of foundation or earth to avoid heat loss. But just the ground under your building seems to work well enough.

rekabis4• 6 months ago

Ground sourced heat pumps need either a horrifically expensive vertical bore hole going down a few hundred metres, or a good acre of land for laid-down piping. I have neither the money nor the horizontal space. So I am thinking something compact that needs to go only about 6-10m vertically into the ground (so I can hide it fully underground with about a metre of soil on top), and take up the horizontal space of 4 parked cars. I have more than enough room and cash to have that cube of space dug out.

And being on an alluvial plain, if I filter out all the rocks larger than a pea, a good 90+% of what is dug out can immediately be trucked away.

fy20• 6 months ago

I ran the numbers for this a while ago. I live where we have proper winters (currently -22c). I wanted something simple just with solar thermal and water pumps (no heat pump). Sand batteries work at an industrial level, but for domestic use you want something simple so that means just water.

A 100m3 (100,000 litres or 26,500 gallons) cylindrical water tank (approx 5x5m) buried and insulated with 50cm of XPS could provide around 4000kWh of deliverable heat throughout winter. Which would be more than enough for heating and domestic hot water for my house.

In the summer you'd use solar thermal to charge it to 85c. In the winter you'd run water through underfloor heating and discharge it to 35c (so you just need a mixer valve and pump).

The structural engineering part of it isn't actually that complicated (with a garden on top, not a house). You can buy plastic water tanks of that size, it just needs to be buried and have XPS foam placed around it.

Because it's volume, it scales up well. An extra one meter in each direction would increase the volume by around 60%, but you have a lower overall heat loss, so the heat capacity would more than double.

The important part of it is the XPS foam though, without this the loses are too great and you don't retain any heat. This is why insulating your foundation and slab is so effective.

eande• 6 months ago

Interesting practical approach to actual build it. Did you do a cost analyses or RoI?

bilbo-b-baggins• 6 months ago

So… store heat in an insulated swimming pool 10ft deep, 30ft wide, and 90ft long, at 185F, above the service temp for XPS foam, got it, ok. At least you could also use it to sous vide an entire cow.

rekabis4• 6 months ago

Pedantic Pete here:

  • The centigrade is capitalized when used after a number. There is also a singular glyph for the entire degree-centigrade convention: ℃.

  • There are also superscript numerical characters to use with volumes, without having to use formatting: m³.

UTF-8 is fun! As is automatic text replacement, once you have the appropriate triggers set up.

Xylakant3• 6 months ago

This exists, in german it's called Eisspeicherheizung. You have a few cubic meters of water buried in a concrete bunker and you use a heat pump to pull energy out of the water until it freezes. The system not only uses the thermal mass of the water, but the thawing/freezing energy which is higher than the energy required to heat water by 1degree by a factor of 80 - meaning if you freeze 1kg of water, you need to pull out enough energy to heat one kg of water by 80 degrees.

You can then use a heat pump that's optimized for the expected temperature range and you don't even need to insulate your water storage tank - you actually want the cold in winter to seep out into the surrounding soil, free energy.

In summer you have cold storage for your AC.

aidenn0• 6 months ago

I live in a climate where, for most of the year, the daily high-low temperature range includes 20C, so I'd like a whatever sized one is needed to average that out, and run most of the year without any active heating or cooling.

BenoitEssiambre• 6 months ago

Yeah I always wondered if I ever switched to solar panels, would there be a way to accumulate heat to be used in the Canadian cold months that have little sunlight? The closest I found was electric thermal storage based on heating bricks. They can accumulate more energy than water since they can go to higher temperatures. For example these say they go to 1300°F or 700°C https://steffes.com/ets/roomheater/ . They don't seem to have large models that could heat a house for months however.

Neywiny2• 6 months ago

This is similar to nighthawkinlight's videos on phase change materials. It was very cool to see how his Ziploc bags of homemade goo helped regulate temperature.

schiffern• 6 months ago

In this work the authors use a ceramic-coated extruded aluminum heat spreader to improve thermal conductivity through the bulk PCM, but I wonder if the graphite flake+powder additive demonstrated recently by Tech Ingredients[1] would be a viable alternative? It might need a stabilizer (thickener) to prevent the ingredients from separating.

[1] https://www.youtube.com/watch?v=s-41UF02vrU

syntaxing3• 6 months ago

With the adoption of sodium batteries, I wouldn’t be surprised if solar panel + sodium battery would outperform this system by a lot.

belviewreview2• 6 months ago

A heat pump gets more heat from a given amount of electricity than if the electricity is use for resistive heating. So the ideal design is solar cell + sodium battery + heat pump.

gpm• 6 months ago

Also when the temperature differential is lower, so ideal might be solar -> battery (to time shift to warmest outdoor temperature) -> heat pump -> thermal battery (to time shift to when you need heat).

Does seem like a lot of added complexity (and likely machinery cost) though.

coffeebeqn• 6 months ago

There’s also solar thermal panels that heat up a liquid circulating in the system and cut out the need for a battery - and can just store the heated liquid.

mrguyorama• 6 months ago

Efficiencies and effects are at the point where taking a photon, converting it into an electron, and using that electron to pump heat is more efficient than turning that photon perfectly into kinetic energy.

Similarly, in mild weather, it is more efficient to burn hydrocarbons and turn it into electricity to run a heat pump than use that hydrocarbon for it's heat energy directly.

Pumping heat is more efficient than making it.

manmal7• 6 months ago

Climates that need a hot tank of water to buffer for heat pumps, will not have meaningful solar panel output during winter. Or do you mean, just load the battery when electricity is cheap? A tank of water is 1k max, probably 10% of a sodium battery.

Youden2• 6 months ago

Even LFP batteries can work out better.

I live in Switzerland where these are available. A Cowa 58 [0] costs CHF 4692 [1] and stores up to 13.5kWh. If you're heating the water with a heat pump, that's ~6kWh of electricity, so ~CHF 782/kWh.

I'm in the process of installing a 33kWh battery and the battery + inverter cost CHF 13600 in total for just the hardware, so ~CHF 482/kWh.

If you add solar panels, the inverter does double-duty producing AC from both the battery and the panels. The battery does double-duty producing both hot water and allowing you to use solar energy outside the times when the sun is shining.

That said, having ordered a heat pump recently and being in the process of having solar + batteries installed, the amount of electrical work needed for the solar/battery install is substantially higher than was needed for the heat pump and here, the labour costs quite a lot, pushing the upfront cost difference even higher.

I think that's where these heat storage things fit in: they have a much lower upfront cost. No matter how cheap the battery, for it to be useful in a Swiss residence, it needs to output a substantial amount of 3-phase power (3-phase is standard here, even in most apartments), which means you need to spend a couple thousand Francs on an inverter and electrical work. These heat storage devices are quite cheap and don't even need someone qualified to handle refrigerants, I imagine they could be installed by a normal plumber.

That reduced upfront cost makes them far more accessible than electrical batteries, at least for now.

[0] https://www.cowa-ts.com/uploads/files/Dokumente/Datenblaette...

[1] https://nettoheizungshop.ch/Cowa-COMPACT-Cell-58

Havoc• 6 months ago

Starting to get more optimistic about our energy future. Things seem to be tracking pretty good

hedora2• 6 months ago

I wonder if this can store any heat or just heat pump heat. If it can store any heat, it would help a lot to further reduce heating costs in our modern energy efficient house.

Sometimes, in the winter, we get too much solar forcing, so if we don’t heat all, it can be 85F in the day in the house, but 60-65 at night. (We open the windows during the day, and don’t always close them at exactly the right time at night.)

direwolf203• 6 months ago

Heat pump heat is just heat.

karussell3• 6 months ago

I think this can work and instead of that the heatpump pumps the heat into your house (when "solar is plenty") it would pump it into the storage. (I have a similar setup, but heat the water but of course this is rather limited)

unrelated: a simple technical solution to your window problem would be home assistant and a few sensors to notify you when the windows are open too long or open when too cold inside.

hedora2• 6 months ago

It’s more about predictive modeling: At what time + temperature do you close windows, given predicted cloud cover and overnight temperatures/wind?

Come to think of it, if we had a big salt slurry that transitioned at 72F in the floors, that would probably do the right thing. It’d create a step function making it hard to heat above 72, or cool below it.

I wonder how much density changes as these things transition. Would a static pool (mixed by freezing) work, or would it need a pump?

ifwinterco3• 6 months ago

It sounds like you need more thermal mass, a traditional brick/stone house wouldn't have that problem

chickenimprint• 6 months ago

So it's a large version of those rechargeable hand-warmers?

ZeroGravitas4• 6 months ago

Yes, it's the same tech. There's been products on the market for a while even though this press release tries to spin it like it's new and linked to heat pumps.

mrexroad• 6 months ago

IIRC BMW used to have a form of this in their cars about 25-30 years back so that the hvac would be able to blow heat before the engine coolant was up to temp after sitting overnight.

hnburnsy3• 6 months ago

Related, TIL the US is effectively banning residential electric resistance water heaters in 2029, with heat pump water heaters being the only type that can meet the new standards. Users will see a 2-3x in cost difference and a 3 to 8 year payback on savings.

cucumber37328422• 6 months ago

Is that 2-3x before or after the plumber marks it up?

What an exceptionally moronic thing to ban, the market solves this naturally. Resistance heaters are 100% efficient whatever fraction of the year is heating days. So if that's 1/2 the year and the water heater can't last 16yr because of water quality the heat pump heater will never pay you back.

This reminds me a lot of the time some jerks in west coast desert states convinced the feds to regulate plumbing fixtures so that eastern "we take from the river and put back in the river" municipalities that have more water than they know what to do with have to suffer through low flow everything.

hnburnsy3• 6 months ago

Heat pump water heater (hybrid/HPWH, e.g., 50–65 gallon equivalent): Unit prices range from ~$1,500–$3,000+ (most common models $2,000–$2,500), with total installed costs $2,500–$5,000 (higher if electrical upgrades or space mods needed). Average retrofit/install often lands around $3,000–$4,000.

direwolf203• 6 months ago

Is the heat pump heater taking heat from inside or outside the house?

beAbU• 6 months ago

Heat pumps are effectively more than 100% efficient fyi. You put 1000W of electricity in, you get 2500W of heat going into the water. (Numbers are only illustrative)

Running cost of heat pumps for heating is much much lower than resistive heating.

pkulak• 6 months ago

If you're making plans 3 years out in the US, you're a fool.

Sabinus• 6 months ago

That's a Biden-Harris administration action. What are the chances that Trump deletes it as a 'Democrat/WEF climate hoax con job' as soon as he's made aware of it?

amazingman3• 6 months ago

This is exactly the kind of thing government is for, even though it's missing the other half: subsidies. At the very least buying heat pumps for the next 5 years should be tax deductible. Even better: a $2000 or similar rebate.

DangitBobby4• 6 months ago

That's probably exactly what will happen.

    Energy property - Heat pumps and biomass stoves and boilers

    Heat pumps that meet or exceed the CEE highest efficiency tier, not including any advanced tier, in effect at the beginning of the year when the property is installed, and biomass stoves and boilers with a thermal efficiency rating of at least 75% qualify for a credit up to $2,000 per year. Costs may include labor for installation.

    Qualified property includes new:

    Electric or natural gas heat pumps
    Electric or natural gas heat pump water heaters
    Biomass stoves and boilers

https://www.irs.gov/credits-deductions/energy-efficient-home...

lm284694• 6 months ago

even though it's missing the other half: subsidies

It's a double edged sword. In my country everyone bought pellet stoves because of the subsidies, hundreds of companies popped up, now that the subsidies have been phased out, 90% of the companies went down, with their support and warranties of course. The 10% that managed to survive increased their prices, which is easy to do once 90% of your competitors went bust

People who thought they'd save money by having the government (their taxes really) pay the bill are waking up 5 years later with expensive maintenance, the first units are starting to fail and need to be replaced but they can't afford it without the 50%+ subsidies. Not to mention that the prices pellets goes up and down faster than your average shitcoin.

rayiner2• 6 months ago

The subsidies and rebates are a scam. The installers just jack up the prices until they capture the entire value of the rebate.

seiferteric• 6 months ago

The problem is, energy use is only one part of the equation. Often times new appliances that are more efficient end up being more prone to breaking due to more complexity and companies trying to cut costs to meet a price point. This leads to people needing to replace there appliances much more often which really makes me question how much energy is actually saved if you include the energy used to produce them...

reorder9695• 6 months ago

I don't know about all heat pump systems, but mine at least requires the water tank to have a resistive immersion too. If the tank temperature gets below some threshold the heat pump refuses to work and turns the immersion on instead until it's warmed up enough.

AlexandrB2• 6 months ago

The problem with heat pumps replacing electric heaters (in cold climates) is that the waste cold air gets dumped into the house and needs to be heated again. Generally, electric water heaters are expensive to run compared to gas ones, so people use them in places a gas heater is not possible to install (e.g. no way to vent the exhaust). This also means that the heat pump would have nowhere to vent cold air.

This kind of thing is why I don't like bans like this. The specifics matter a lot.

grigri907• 6 months ago

Your heat pump ought to be venting the cold air outside in the first place. If you're pulling the heat for your water out of your conditioned air, yeah you're in a losing battle.

elric2• 6 months ago

That seems like a stupid ban. Heat pump water heaters are impossible to install in many smaller dwellings, even if we're ignoring the need for large storage tanks.

The only problem with resistance heaters is the large current draw to heat water for bathing. Central heating can be done at lower temperatures (as is the case with heat pumps), but bathing cannot.

There are some resistance heaters with built in (electrochemical) batteries aimed at reducing peak current, but I'm assuming the ban would affect those as well...

chickenbig• 6 months ago

Perhaps I am missing something; this product already exists as the Sunamp Thermino.

https://sunamp.com/en-gb/hot-water-solutions-thermino-range/

ZeroGravitas4• 6 months ago

It also exists, as described in the headline, as a tank of heated water.

The phase change stuff has positives like taking up less physical space but it's also a much less mature tech than storing hot water.

DrScientist2• 6 months ago

Indeed.

In the UK there was a unfortunate trend of ripping out these energy storage devices and replacing hot water tanks with on demand electric hot water heating ( only heat the water you need ). And new builds often have no tanks ( as it saves space in the new tiny homes ).

Very short sighted in my view - a very simple way to store energy and everyone uses hot water directly.

vee-kay2• 6 months ago

You are right in your analogy.

Earth's oceans and seas act as giant heat sinks.

And that means more trouble as global climate change impacts..

https://www.earth.com/news/ocean-warming-broke-records-for-4...

Nition• 6 months ago

It's funny how useful water is for power generation.

There's heat storage as discussed here.

Or you can store cold water in a reservoir as a giant battery, pumping it up high when you've got excess power, and letting it back down to generate hydroelectricity from it later.

Or you can boil water to make steam that spins a turbine and use it to convert anything that can heat water (coal, oil, nuclear...) to electricity.

shellfishgene• 6 months ago

I think the advantage is that hot water loses heat over time, depending on how good the insulation is. However with phase change materials, the heat is trappped in the phase change and is stable until you release it.

metalman• 6 months ago

the idea is theoreticaly good, but as it depends on sealing incompatable materials apart, there will be problems, and issues with disposing of failed units.Dry sand works as thermal storage without any issues, and only needs more space, competition will be stiff.Water also works, and ordinary off the floor systems can be used with no modifications. The only advantage the system will have is in places where space constraints combine with the desire for fancy solutions and ecobabble.

animal531• 6 months ago

Where I live we need a way to store and distribute cold as needed.

burnt-resistor2• 6 months ago

Stanford's cogen plant has an underground "ice cube" for campus/municipal chilled water infrastructure. Perhaps scaling something like that makes sense or perhaps to use an absorption heat pump (AHP) that can operate like and the reverse of an Einstein–Szilard refrigerator?

Joel_Mckay• 6 months ago

They are a very efficient way to get both AC and Heating:

https://www.youtube.com/watch?v=7J52mDjZzto

https://www.youtube.com/watch?v=7zrx-b2sLUs

Unless you live in a cold climate, they are worth it for a discounted energy bill =3

burnt-resistor2• 6 months ago

Private equity / Wall St. megacorps want to sell you complex systems that are fragile, unaffordable by the 99%, have short warranty periods, wear out quickly, require cloud logins and proprietary maintenance parts, and are mandated by law.

GFL buying a simple resistive-heated clothes dryer, furnace, or tanked/tankless water heater in 2030.

chankstein38• 6 months ago

They should've used lasagna. You could be in a tundra heating it over a fire and, as long as you get it sufficiently and consistently hot, it'll still burn your mouth 20minutes later.

cromka2• 6 months ago

I was recently wondering if any particular type of food contributes to mouth cancer prevalence and I concluded that at the top of that list would be be lasagna and cherry tomato on a pizza/in a soup.

sandinmyjoints• 6 months ago

Why?

Loughla• 6 months ago

And yet, if you make it like I do, there always manages to be one piece that is ice cold while the rest is shockingly hot. Even if you're start with warm ingredients.

Physics does not apply to lasagna.

Also I suck at making lasagna.

LoganDark2• 6 months ago

I don't know how you cook your lasagna, but cooking for longer at a lower temperature usually results in more even heating than cooking for less long at a higher temperature. (This is one of the reasons microwaves are so terrible at heating evenly.) If you're not already, that may help.

(I also imagine using the circulation in a convection oven might help as well. Also, preheating your oven! Even if it's a toaster oven.)

apatheticonion• 6 months ago

Also pies

https://www.youtube.com/watch?v=aEAHLFvD3v4

Joe_Cool• 6 months ago

Try Toast Hawaii. The weird mix of ham, pineapple and cheese the Germans make.

I am still convinced the lava cheese insulator is there only to burn people's insides with boiling pineapple.

moi2388• 6 months ago

But that’s because of the water content of pineapple, so now we’re back at water..

Although pineapple flavoured floor heating does sound delicious.

x______________• 6 months ago

Thanks for the recommendation, I will go out and try this, despite the belief that some people hold about Hawaii Toast giving you cancer[1].

1: https://en.wikipedia.org/wiki/Toast_Hawaii

mekdoonggi• 6 months ago

Sometimes I wonder if the people trying to create a fusion reactor have ever made a baked potato, because I swear it's halfway there.

sokka_h2otribe• 6 months ago

To whatever degree you are serious, this can be a phase change thing.

Cheese melting takes energy Cheese freezing, releases energy.

So you do actually get the temperature to remain at the melting point of the cheese for a longer period of time if you have enough % cheese to be significant.

BrtByte3• 6 months ago

It's actually the same physics: layers, trapped moisture, and phase changes holding onto heat way longer than you expect

jandrese2• 6 months ago

I've been keeping an eye on heat pump water heaters for awhile, but right now they mostly make sense in warm climates. The big problem is they're still specialty products and marked up like crazy, but also they tend to use cheap components which makes them loud and prone to failure. If you run A/C for the majority of the year then they pay themselves back reasonably quick, barring early failure, but in colder climates they make your house work that much harder to keep the space warm.

The most optimistic hope is that the government mandate will force enough demand that manufacturers can enjoy some economies of scale and actually try to compete on price. I don't think this will happen anytime soon.

Tor36• 6 months ago

I had a heat pump installed in 2010. In a cold climate. Only used for heating. It paid for itself extremely quickly - less than three years. It's still going strong, in 2026. It's important to maintain it regularly, i.e. deep cleaning every two years or so. The first time I got a company to do it for me, and the technician taught me how to do it all by myself, so that's what I do. In any case having a professional doing it wasn't expensive either. And I clean the dust filters (very easy) every second week or so.

stuaxo2• 6 months ago

What did you heat with before?

snuxoll• 6 months ago

Installed mini-splits to replace the propane stove that heated my house, DIY job, so all it cost was the units themselves and some materials.

Propane bill (no natural gas, town of 500) from Oct 24 to Feb 25 (installed the mini splits that month) was $1200, for just heating.

My mini-splits are on a dedicated sub panel with an Emporia Vue 3 energy monitor. $604 in electricity consumption, and that includes air conditioning over the summer months.

For what it’s worth, our winter weather averages 25-35F with the occasional few days dipping to tens, single digits, and the occasional -10 freak; but these units just BARELY have a HSPF4 rating to classify as “cold climate” models. Still going to pay for themselves in 6 years without any tax credits, and 4 or so since I still installed them when they were available.

matwood2• 6 months ago

I think a heat pump only for water isn't the right way to go. In the EU, new systems I see use a single heat pump for all heating and cooling in the house including heating water.

I do miss my natural gas on-demand water heater from when I lived in the states though. Unlimited hot water was nice, and it took up almost zero space.

spockz• 6 months ago

Which models are you looking at? I was still quoted separate pumps for floor heating and a boiler with the pump built in taking the energy from the air two years ago.

Is it something from nefit by any chance?

thunfischbrot• 6 months ago

Afaik heat-pumps in the EU can provide unlimited hot water–what am I missing?

luckystarr• 6 months ago

While they are not as efficient or flexible, they are many times more efficient than resistive electric water heaters. I've installed one with in house air intake (due to construction reasons) in my house and it cooled down the basement by a few degrees (and removed air moisture as an added bonus). In summer the thermal capacity of the ground heats up the basement again, in winter it's a bit cooler, but it still works efficiently.

globular-toast• 6 months ago

I do miss my natural gas on-demand water heater from when I lived in the states though.

Isn't that what we call a combi boiler in the UK (and Europe?) I've recently moved from having a big hot water cylinder to a combi. The space saving is nice, but there are downsides.

Waiting for the hot water to come through is annoying and I'm often just wasting cold water waiting for it to come through hot. There is a "pre-heat" feature which would be nice, but then it would keep it warm 24 hours a day which is ridiculous. Maybe some better boilers can time the pre-heat. That would probably be close to perfect.

The other downside is it can only really supply one tap with hot water. So if someone is having a shower and someone else runs a hot tap it can be unpleasant. Requires some coordination between householders.

All in all I would definitely prefer a cylinder if I could afford the space it takes. Modern cylinders are incredibly efficient. I once turned the heating off for a week while away on holiday and when I came back the water from the cylinder was still tepid.

stuaxo2• 6 months ago

They use them a lot in Norway, it's hardly warm there.

ortusdux2• 6 months ago

I'm in the northern US and am very happy with mine. I self-installed with a county rebate, so the total cost was a Saturday and $700. My old electric unit was EPA rated for $450/year, and the new one has averaged $170/year over 4 years, so I've already broken even.

gwbas1c8• 6 months ago

You're about 20 years behind.

My heat pump is working great at 0F. It's 7 years old.

baggachipz• 6 months ago

heat pump for house !== heat pump for hot water

jcgrillo• 6 months ago

Mine are in climate zone 6. They're only a couple years old. The coldest temperatures I've run them at so far are -21°F and they kept the house adequately unfrozen. They'll maintain a COP of 2 down to 5°F IIRC. The hot water heater is an 80gal Rheem heat pump unit. No complaints there either. It would be pretty great to have some thermal storage though, temperatures in the dead of winter here are usually above 5°F during the day but drop well below zero at night. Blasting the heat pumps during the day to bank heat for overnight would be far more efficient.

hippo223• 6 months ago

It really depends on how well your home is insulated. Heat pumps don’t work well on old, poorly insulated houses in cold climates. If they can keep up, which is a big if, the price of electricity generally dwarfs natural gas, even if the heat pump is running at 250-300% efficiency.

themafia2• 6 months ago

government mandate will force enough demand that manufacturers can enjoy some economies of scale

So you want the government to pick winners and you want to do business with a monopoly? This is the opposite of what you would want.

If the product saves me money, and it's _actually_ better, I will buy it in a heartbeat. If you're involving the government it's because one of those things isn't true.

enaaem• 6 months ago

Gas infrastructure is expensive to build and maintain. Often times with tax money. What tend to happen in Europe is that they phase out gas by not building gas lines for new development.

lizknope• 6 months ago

Ask This Old House had an episode literally yesterday where they installed a \ solar-assisted split heat pump water heater. There is a component that goes on the outside of the house but not on the roof which simplifies installation.

https://www.youtube.com/watch?v=uqyAWkXXt3A

https://www.neshw.com/residential/solar-heat-pump-water-heat...

newhotelowner• 6 months ago

They marketing like it's an expensive tech, but it's pretty cheap.

We have been buying heat pump PTAC for the hotels for last 20 years, and price difference is usually 5% between with and without heat pump.

Seems like all companies are colluding with each other for marking up prices.

tempestn3• 6 months ago

We somewhat accidentally ended up with a good combo: we have a ventless heat pump dryer, and a heat pump water heater, also in the laundry room. So when doing laundry, the water heater cools the room while the dryer heats it, so they roughly cancel out.

As an aside, HP dryers are really elegant tech, and it's a shame they're not more common. They use the heat pump not just to heat the air in the dryer, but also to condense the moisture back out of it, so just the water can be drained away instead of needing to exhaust the air outside. So you need much less energy overall, and you don't need a dryer vent. The only downside is they're a bit slower, but ours has a resistive backup option for when you need clothes dry asap, so really it's just price.

zhivota• 6 months ago

Heat pump dryers work at a much lower heat as well since much of the heating of a traditional dryer is lost out of the vent. The heat pump condenses the water out of the hot air so you don't lose the heat.

I've stopped needing to sort my clothes out as a result, I used to hate putting synthetics in a regular dryer because they get worn out so fast that way.

jonstewart• 6 months ago

I bought a Samsung HP dryer a few years ago and it'd be great except for a terrible design flaw where lint gets trapped in its heat sink fins, turning into a soggy mess.

danielovichdk• 6 months ago

Stones has the ability to store heat and keep cool.

What's all this fuzz about ?

Etheryte• 6 months ago

It's all about efficiency. You can store heat in anything, but the question is for how long and how much energy can you get back out later. The first part is easy and how we got ovens and stoves, the second part can be pretty tricky depending on your requirements. Large scale energy storage sometimes uses massive amounts of sand for example, but they heat it to hundreds of degrees which is not really feasible in most settings.

ortusdux2• 6 months ago

I was interested to learn about cold district heating recently, which is basically a municipal scale geothermal system.

https://en.wikipedia.org/wiki/Cold_district_heating

yowayb• 6 months ago

I went to Moscow in December several years ago and learned they've got one the world's largest district heating systems.

xattt• 6 months ago

I am not sure if this is still the case, but up to 20 years ago, these were typically shut off in May-June to August for “maintenance” which resulted in a prolonged period of no hot water in apartments.

gwbas1c8• 6 months ago

The article omits some critical details:

It says this is both a "heat pump" and also "storage" AND says that it will run when electricity is cheap or plentiful. Thus:

1: Where does it pump the heat from? (Or is this not really a "heat pump" and instead is using resistive heating?)

2: How long does it store heat? Is this something that will store heat on a 24-48 hour basis, or will this store heat during the spring / fall when longer days mean extra power from residential solar, and then use the heat in the winter?

3: Is the unit itself "warm" when storing heat? Or is the heat stored in a purely chemical way and needs to run through a catalyst or similar to get it back?

4: Can this be scaled up for general domestic heating?

---

Just an FYI: There are plenty of schemes with resistive electric water tanks to store heat when power is cheap.

mike-the-mikado• 6 months ago

I would guess that is intended for a daily cycle, perhaps using air source heat pumps at times of day when the air temperatures are higher and electricity prices are lower, then using it as required.

As it works on phase change (e.g. think of melting ice) heat is added (or removed) without changing the temperature of the store (which, I guess, might be hotter or colder than where the heat is extracted or used).

gwbas1c8• 6 months ago

But how hot does the heat source have to be?

Depending on the needs, resistive heating can get hundreds of degrees hot, but the best heat pumps that I know of can only raise the temperature about 60 or 70° f.

IshKebab3• 6 months ago

1. The device is just storage. It would be paired with an air or ground source heat pump.

2. With good insulation you can easily store heat for a day which is all you need. You're never going to get close to storing summer heat for the winter. That's not impossible but not feasible for something this scale (and not cost effective at any scale).

3. You just heat it up and cool it down. There are no fancy chemical processes happening other than the phase change. It's exactly like a phase change hot/cold pack you can buy on Amazon.

4. I'm pretty sure this is designed for domestic heating...

It's kind of an obvious idea tbh. I don't think they've done anything super innovative... They made an aluminium heat sink..

butvacuum• 6 months ago

the only new thing- no matter how they do it- is putting it on residential instead of commercial or industrial installs.

my childhood public school took us to some big commercial building- I think it was Sears' HQ- and they proudly showed us the huge blocks of ice providing chill during the day.

npodbielski• 6 months ago

With good insulation you can easily store heat for a day which is all you need. You're never going to get close to storing summer heat for the winter. That's not impossible but not feasible for something this scale (and not cost effective at any scale).

This is ground basically. How deep varies but few meters underground you basically have average yearly temperature. You could pump heat from house to the ground to take it out from the ground during winter.

tootie2• 6 months ago

Presumably it's air source and if it's indoors it will just be the air in whatever room it's in. That's how my ventless dryer works. I'm not sure what the implications are for taking heat from air that may have been heated by another heat pump are for efficiency. But also if it's summertime, they may be relieving load from your air conditioner.

gwbas1c8• 6 months ago

That's how my ventless dryer works.

Do you mean a heat pump dryer? Those aren't taking heat from the room; they work by sending the air inside the unit through a powerful dehumidifier. (I have one, it's very nice.)

Epa095• 6 months ago

Not many numbers in there. I would be interested in some measure of energy and effect per volume, e.g how many kWh of heat are we talking about at e.g 1 liter, and how fast (kW) can it produce it?

5ersi• 6 months ago

It uses phase change (solid to liquid) to store heat at about 200 kJ/kg. Compare this to heating water in a boiler from 10c to 60c - stores 209 kJ/kg.

So we already have an effective way to store heat which can work for decades without servicing and is also cheap to produce (in terms of money and energy consumption).

thescriptkiddie• 6 months ago

one difference is that a phase change stores energy at constant temperature, which may be desirable given that heat pump efficiency is inversely proportional to temperature output temperature

LoganDark2• 6 months ago

I feel stagnant water would be more annoying for maintenance than something like salt hydrates.

Marsymars3• 6 months ago

There are also existing commercially-available residential units (e.g. Ecombi or Steffes) using ceramic bricks that are in the ~450 kJ/kg range.

sbierwagen• 6 months ago

Note for the confused: Ecombi achieves this by heating the bricks to dramatically higher temperatures using conventional resistive heating elements, thereby storing more energy, even though the specific heat capacity of any ceramic material is dramatically inferior to that of water.

But, as a result, Ecombi has a much lower system efficiency than a heat pump, since it's essentially just a space heater pointed at a rock. It only makes sense for jurisdictions with time-of-day variable pricing of electricity, and trades off simplicity and low initial purchase price for lifetime cost.

raffraffraff• 6 months ago

I don't know why these aren't used more in building fabric. There's a youtuber who makes these phase change solutions out of various salt mixes aiming for the correct change temperature for a specific application. Eg he made panels for his shed roof (keeps it cooler in sun, warmer at night). Obviously this works better to smooth out large, reliable daily temperature swings, and offers little to someone in a constantly hot or constantly cold place.

I live in Ireland where night/day temperature swings are small. To cool my attic on a hot summer day I'd need to move that heat into a large water tank that gets used for laundry, cleaning, showers etc and is refilled from cold mains water. But fitting an air to water heat exchanger inside my attic would be a big expense and I would have to make sure I didn't freeze the attic.

Regular air to water heat pump could be hooked into my existing tank I suppose?

TobTobXX• 6 months ago

The name of the YT channel is NightHawkInLight[0] btw. Absolutely worth checking out. He creates materials with extremely useful properties from household materials (eg. PCM (high heat capacity), highly reflective paintings, Aerocrete (high insulation/fire resistance), ...)

[0] https://youtube.com/@Nighthawkinlight

jcattle2• 6 months ago

Does heating water in a boiler work well with a heat pump? How about a release of energy 10 hours later (peak solar at noon, to first shower the next morning)?

I actually don't know the answer. I'm just thinking that there must be more to it, if the answer was as simple as "just heat water".

moooo992• 6 months ago

It does. However, the hotter the water becomes, the less effective the heatpump becomes. With anything beyond 60C becoming very inefficient.

With hot water tanks, they are unfortunately pretty badly insulated as well, with some of them loosing heat very quickly. Depending on how you plan on using that water, you also have to make sure the temperature never dips below ~60C to avoid legionella from spreading.

I actually think that heating your home slighly higher than you‘d usually do is the simplest and most effective approach, assuming it is properly insulated. Just rise the target temp for 1-2C when the energy is cheap and reset it once it isn‘t. Probably not as efficient, but extremely simple to implement.

masklinn2• 6 months ago

Does heating water in a boiler work well with a heat pump?

Sure, heat pump hot water tanks are a thing. Air-to-water heat pumps are less efficient than air-to-air as they need to reach higher target temperatures, but it will be more efficient that straight resistive heating by a factor of 2 at low input temperatures, and 3+-ish at high summer temps.

The primary concern would be the quality of the tank’s insulation. I would hope HPHWTs are good on that but if you’re looking into that you probably want to double check the heat loss of the tank.

elric2• 6 months ago

What about heat per unit of volume? Seems like the selling point is that a pretty small box can service a whole bathroom. Presumably it has a higher density than water and requires less insulation?

leoedin3• 6 months ago

I think this is the most crucial part. External heat pumps are OK - people install air conditioners everywhere already - but most houses/apartments aren't set up for large water tanks. The interior heat storage needs to be comparable in size to the existing gas boiler.

Alex-Programs• 6 months ago

Heat transfer is based on temperature difference, not heat difference. This way ought to reduce heat losses and improve efficiency.

jokoon• 6 months ago

I'm interested in storing cold, not heat

Storing cold during the night is probably more efficient

I thought about making ice blocks with a freezer on my balcony, probably not a good idea

ryzvonusef• 6 months ago

Persians had a system since 400 BC:

https://en.wikipedia.org/wiki/Yakhch%C4%81l

jaapz• 6 months ago

But storing the heat they produce has not been possible

Many heat pumps are installed with a large insulated buffer of water (for ex. 300L), which stores heat pretty well?

And homes that use underfloor heating in concrete can store heat pretty well too. Many people use that to heat up the home when energy is cheap and disable the heat pump when it is expensive.

V__• 6 months ago

Water (given enough volume) is a pretty good heat storage.

https://youtu.be/Bm7L-2J52GU?t=270

mock-possum• 6 months ago

It can be a pretty good ‘battery’ too

https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit...

BrtByte3• 6 months ago

It's not that heat storage didn't exist, it's that this is closer to a "thermal battery" than a thermal flywheel

BrtByte3• 6 months ago

An 85% round-trip efficiency and 4X smaller volume sound great, but how does the installed cost compare to just oversizing a hot water tank or running the heat pump harder during off-peak hours?

labcomputer• 6 months ago

That’s essentially what they’re doing. The innovation is an engineered material having a specified temperature of phase change.

So the temperature swing is smaller (almost zero) so heat losses due to non-infinite insulation are reduced.

Pretty soon, heat pumps will be able to store and distribute heat as needed

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