9 ms·

Hitachi launches CO2 heat pump water heaters with solar-friendly tariff controls

321 points by thelastgallon 1mo ago

throw0101d 1mo ago
CO2 as a refrigerant isn't new: * https://en.wikipedia.org/wiki/R-744 https://en.wikipedia.org/wiki/R-744 It's just not as prevalent in the residential HVAC market (which this product serves?), and more in the commercial/industrial space (probably because of the higher pressures needed to get into a liquid state).
- Lwerewolf 1mo ago
  There are resident systems, and they're of exactly the type listed in the article (i.e. water heaters). Residential... area heating pumps, so to say, are moving towards propane (afaik). I've been looking into getting a propane monoblock air-to-water pump, with an antifreeze loop towards an indoors heat exchanger / water tank.
  - adaml_623 1mo ago
    Trends for new refrigerant depends on country... some to R-454B, and some to Propane, doesn't seem like C02 is very common which is a pity because I love the idea of a non-toxic non-flammable super cheap refrigerant. This is for the Japanese market so perhaps the cons of the C02 systems are outweighed by the safety aspects.
- alex_duf 1mo ago
  It's useful though, as I think (correct me if I'm wrong) that the gases generally used in HVAC tends to have much worse warming effect than co2 per volume. We do need heat pumps deployed at large scale, but sometimes I worry we don't understand they need to be handled with care at the end of their life
  - PunchyHamster 1mo ago
    If it is outside you can just use propane as refrigerant. Low warming value and it leaking to outside doesn't matter, not gonna catch on fire. There are indoor devices using propane but they generally come with caveat "must be installed on room at least this m3", precisely so if it leaks it doesn't get to density that allows explosion
    - jabl 1mo ago
      I believe there are propane using split AC systems where propane is used only in the outside unit. The outside unit has a heat exchanger transferring the heat to some glycol-water solution which is what then circulates through the inside unit.
    - 27183 1mo ago
      I currently have R410a heat pumps with minisplits, when they're off warranty sometime in the future I might consider putting propane in them. The main question would be whether the oil used with R410a is compatible with propane as a refrigerant. This is probably a little bit "dangerous" in the sense that I'll have high pressure propane in the line sets and minisplits inside the house, but it's a very small volume of propane and not really any more dangerous from a fire perspective than my propane fired condensing gas boiler. [edit] a little internet sleuthing indicates that hydrocarbon refrigerants "might be" compatible with basically any oil, so I can probably just continue using whatever oil is in it.
  - moepstar 1mo ago
    Yes, that dangerous effect is indexed as GWP - global warming potential. CO2 has a GWP of 1 in this context, while other refrigerants are worse - for example, R32 has a GWP of 675 (so 675x worse if it escapes), not sure about R290 (Propane), which I believe is either about 40 or 14… Regarding EoL: At least around here, household appliances such as fridges are brought to a recycling yard and are properly taken care of in that regard… and as for heatpumps - those are only to be installed by certified professionals, for this very reason.
    - 1mo ago
- arpinum 1mo ago
  CO2 does better with large temp deltas, like hot water tanks. Radiators don't produce large deltas - the inlet to outlet diff is typically under 10 degrees. But they run at higher pressures, making the manufacturing more expensive.
- deleted 1mo ago
  [deleted]
- totetsu 1mo ago
  I heard CO2 is a gas with a powerful green house effect. What happens at the end of life of these units I wonder? What if they leak and it gets into the atmosphere!
  - ErroneousBosh 1mo ago
    CO2 has a surprisingly feeble greenhouse effect. Almost anything else you could use as a refrigerant is worse. Even water vapour is a worse greenhouse gas. Edit: wait, have I been whooshed? Apologies if so... ;-)
    - Brian_K_White 1mo ago
      Maybe but at this point I no longer think it's fair to be quite this dry on something that quite so many people would be legitimately sincere about anyway so I wouldn't exactly apologize for being the victim.
      - ErroneousBosh 1mo ago
        > Maybe but at this point I no longer think it's fair to be quite this dry on something that quite so many people would be legitimately sincere about Yeah, but I'm from the UK so I should be able to detect dry humour. It's something that Americans don't really get. You know, like affordable healthcare.
        totetsu 1mo ago
        I apologise, I am at the dry humour stage of climate grief.
        ErroneousBosh 1mo ago
        Take heart in the thought that this is going to ease off a bit in a couple of years when the current solar cycle dies down and the sun is not dumping about 5% more energy into the atmosphere than normal.
- JTbane 1mo ago
  There is no reason not to use propane or butane, they have low global warming potential and is cheap. The fire risk is overstated, no one thinks twice about carrying a lighter in their pocket.
- pjc50 1mo ago
  This has the useful property of being regulation-exempt because it's already literally everywhere. Unlike "F gases", which have much more serious greenhouse effects and are regulated in the UK (and elsewhere): https://www.gov.uk/government/collections/fluorinated-gas-f-gas-guidance-for-users-producers-and-traders https://www.gov.uk/government/collections/fluorinated-gas-f-... You could install your own CO2-based heat pump in a way you wouldn't be allowed to do with a F-gas based one.
  - bluGill 1mo ago
    OTOH, CO2 uses much higher pressures and so I'm more willing to DIY a F-gas based one. CO2 if there is a leak can cut a limb off. F-gas is generally not that high. I wouldn't want a leak/mistake, but CO2 is less personally forgiving.
objektif 1mo ago
“Hitachi has not yet disclosed full efficiency specifications for the two new models. Their predecessors, the BHP-FV37WD and BHP-FV46WD, have annual hot-water and heat-retention efficiency ratings under Japanese Industrial Standards (JIS) of 4.2 and 4.1, respectively.” What does this mean?
- alex_duf 1mo ago
  If I'm not mistaken, it means 1kWh of electricity moves 4.1kWh of heat into your hot water tank. Heat pumps are amazing.
  - PunchyHamster 1mo ago
    well, in case of water heater it moves it from your room to the water. Which means in winter that is extra work for your heating system to compensate for But in climates where heating only really runs in winter it's great
    - Danoch 1mo ago
      [dead]
    - slau 1mo ago
      Technology Connections has recently published an in-depth piece of the advantages and disadvantages of in-room heat-pump water heaters [1]. The tl;dw is that it is significantly slower than a resistive or gas-powered water heater, and lowers the temperature of the room by a few degrees, but nothing major. You have to over-provision them compared to your needs. And they are way bigger. [1]: https://youtu.be/F_7B2shTPPU https://youtu.be/F_7B2shTPPU
      - cogman10 1mo ago
        > significantly slower than a resistive or gas-powered water heater This was TC being a weirdo. He bought a 120V hot water heater. Had he done a regular 240V water heater the recovery time would be comparable to pure resistive water heaters. But the takeaway about cooling is important. These things barely chill the room they are in.
elgertam 1mo ago
> Some Japanese utilities have introduced tariffs designed to encourage daytime water heating as growing volumes of solar generation enter the grid. [Emphasis added.] I was quite confused at the use of "tariff" here, as it meant to me a "tax on a good crossing a political boundary." Turns out, 'tariff' has an older meaning: a published schedule of fees or taxes issued by some authority.
- Aboutplants 1mo ago
  US utilities also have Tariffs. It’s the statement of how the utility operates and charges users for service. Anytime a utility needs to adjust costs/rates, they need to file a Rate Case with the public utility commissions, and resulting in changes to the Tariff.
- _joel 1mo ago
  I've seen 'tariff' used a fair amount here in the UK on price lists (taxi etc)
  - world2vec 1mo ago
    Same in Portugal: a "tarifa" can mean a price charged for a rendered service or a tax on imported products.
- koito17 1mo ago
  The Japanese word used in the context of price lists would be something like 料金表 or 料金メニュー. When I see "tariff", my mind only thinks of 関税 , and I was just as confused as you were. Turns out its just an item in a price schedule.
- myrmidon 1mo ago
  It's an arab loan word for ~"price list" (originally strongly suggesting an import-duty-like meaning). The same word exists in e.g. German or Italian, but mostly just means "pricing scheme" there, like in the article ("import duty" using a different expression in those languages). Might be a mostly/somewhat "false friend" for a German (pv magazine is german).
EspadaV9 1mo ago
I'm actually in need of a new hot water tank and have been looking for a heat pump one. Wonder if these will be available in Australia, and how they compare to the current range.
- XorNot 1mo ago
  I have a heat pump hot water unit in Australia - Sanden: https://www.sanden-hot-water.com.au/ https://www.sanden-hot-water.com.au/ CO2 refrigerant as well.
  - masterj 1mo ago
    I have this one in Canada. Works well! But having water leave the building envelope is a bit scary on very cold days. There are heat traces and freeze valves so it should be fine, but I do worry about power outages during cold snaps
- kalleboo 1mo ago
  The Australian electronics YouTuber Dave Jones (EEVBlog) had a heat pump water heater installed in his house, and while on the outside it was branded "Reclaim Energy", it had a Made in Japan sticker and was internally a Mitsubishi.
boringg 1mo ago
Japan is so far ahead the rest of the world for quality and innovative heat pumps. Quiet, robust, high efficiency in cold climates. I wish they could bring the prices down though. I worry in 15 years we will all have crapily made Chinese heat pumps for a fraction of the cost. Noisy, not robust, copying competitor designs not innovating, lower efficiency but easily replaceable. Theres probably an analogy here with software talent and AI but its too early to do that.
- deleted 1mo ago
  [deleted]
- PaulHoule 1mo ago
  Not everything from China is crap. I'm a big fan of Chinese lenses. I reach for Japanese and German lenses when I want to take the highest quality photographs that look like the photographs all the other photographers take. When I want to take a picture like you've never seen before I reach for https://www.venuslens.net/product/laowa-9mm-f-5-6-ff-rl/?srsltid=AfmBOoppl0TfZiNVsfcMVy6cFS8xNhW0P7EmU4mgd2vanELacSrGxUmj https://www.venuslens.net/product/laowa-9mm-f-5-6-ff-rl/?srs... or https://findingrange.com/2022/01/14/7artisans-photoelectric-50mm-f0-95-lens-review/ https://findingrange.com/2022/01/14/7artisans-photoelectric-... It's true a $3000 lens from Sony has better optical quality than a $300 lens from China, like take a picture of a starry sky and you will see light rays bounce around a lot more inside the Chinese lens. But in terms of value and innovation Chinese lenses have a place, and many Chinese manufacturers are looking for this kind of opportunity for whatever they make.
  - post_break 1mo ago
    China figured out how to make thermal imaging sensors as well. Why would you buy a $4,000 Flir with less resolution when you can get a $400 Topdon. What's funny is now it appears Flir has cut their prices dramatically to compete.
  - 27183 1mo ago
    I have Haier Arctic heat pumps that are made in China. They've been great so far. I've also worked with suppliers in Shenzhen for one-off custom electronic devices that would put western companies to shame in their communication, efficiency, turnaround time, cost, and engineering quality. The new transmission I just put in my truck was made in China too.
kalleboo 1mo ago
I live in Japan and last year when we moved from an apartment to a house we installed a Mitsubishi EcoCute heat pump water heater which already has these features and is also a CO2 heat pump. We have one of the "all-denka" electric plans, where we trade off cheap rates during solar hours for expensive rates during duck curve hours. By having the hot water only run during cheap hours, and having the aircon turned off/down during the expensive hours, we're paying less in energy for our all-electric house than we did in combined electric+gas in our 3x smaller apartment. We pay approx (before fees, and the rates change slightly by season): * 8 AM - 10 AM: 35 yen/kWh * 10 AM - 4 PM: 13 yen/kWh * 4 PM - 6 PM: 35 yen/kWh * 6 PM - 8 AM: 19 yen/kWh Our Mitsubishi has other nice features like it can recirculate the water in the bath through a heat exchanger after you already filled it and got in, so it will keep the water from cooling down to lukewarm, and you can even adjust the bath water temperature if you ended up with filling it with too warm or too cold water. Of course, there's also an app so you can start filling up the bathtub when you leave work for home so a hot bath is waiting for you. There's also an intercom to the kitchen "so mom can tell the kids to get out of the bath, dinner is ready". edit: the wifi integration does have one actually useful feature: if we had solar panels, then it can use data from them to know when to run "for free", and it can use weather data to predict if it should wait for sun or not to run
- koolba 1mo ago
  > Our Mitsubishi has other nice features like it can recirculate the water in the bath through a heat exchanger after you already filled it and got in, so it will keep the water from cooling down to lukewarm, and you can even adjust the bath water temperature if you ended up with filling it with too warm or too cold water. How long do you sit in a bath? > Of course, there's also an app so you can start filling up the bathtub when you leave work for home so a hot bath is waiting for you. My immediate reaction to this is, “there’s a way for my house to be remotely flooded”.
  - kalleboo 1mo ago
    > How long do you sit in a bath? We love our baths here in Japan > My immediate reaction to this is, “there’s a way for my house to be remotely flooded”. I forgot to mention that it senses and automatically stops filling the bath at a select number of liters, even if you start a bath using the physical button when you're at home.
nickpeterson 1mo ago
I live in Ohio in a 100 year old home with cast iron radiators and a natural gas boiler and a gas water heater. I’d love to move to electric but it feels like my only real option for keeping the cast iron is something like the Daikin Altherma 3 H HT. Does anyone more knowledgeable of this part of the industry know of any reasonable alternatives for electrifying old houses but keeping the radiators?
- ErroneousBosh 1mo ago
  Underfloor heating works best with air source heat pumps, so just switch to that. Then run a wee bit hot water through your cast iron rads for the look of the thing.
  - nickpeterson 1mo ago
    I take your point, but what you’re describing would have to cost thousands just in putting in underfloor pipes. It will never make financial sense to do it? Or am I misinterpreting your suggestion?
    - jabl 1mo ago
      I don't see how installing underfloor heating in an existing house can make economic sense. Additionally in older houses the windows tend to be a bit leaky, so the radiators being under the windows is important to prevent unpleasant cold drafts. Yes, the heat pump will take an efficiency hit for using radiators rather than underfloor heating. I'd say that's just part of the cost of living in an old house.
- Aboutplants 1mo ago
  Don’t forget to include the natural gas utility distribution costs when calculating any potential financial benefit when looking to switch to fully electric. Your not only getting rid of the natural gas Energy costs, but since your in Ohio, I’d wager your actual Distribution costs for your natural gas supply is actually greater than your actual Natural gas energy Supply costs. Reducing to simply one utility distribution cost will help substantially when looking at long term financial viability
deleted 1mo ago
[deleted]
thelastgallon 1mo ago
Some background info for context. (for those that may not be familiar). Heat pump conjures up an image of an appliance, but it is a principle of physics. Heat can be created by burning fuel or electric resistance. Cold can't be created. Cold is the lack of heat. Cold is 'created' by removing heat. Fridge keeps the inside cool by moving heat from inside and dumps it outside. This movement of heat is called heat pump (pumping heat in a specific direction). If we can do this for cold, we can also do this for heat. After all, we always have heat in the environment until we get to 0 degree Kelvin. Which means we can have heat pump water heater in the garage. Or heat pump furnace. Creating heat from fuel/resistance is at most 100% efficient (most likely a LOT less). Heat pumps are 400% - 500% efficient per unit of electricity, because the idea is just to move heat. In one direction, or another. All of this is great, until we get to the refrigerant used to transfer the heat. These are very specific chemicals. Mostly synthetic chemicals. Historically, these were Chlorofluorocarbons (CFCs). CFCs caused ozone depletion and have high GWP of 14,400. What is GWP? CO2 is a warming gas that has Global Warming Potential (GWP) of 1 (the standard). Earth radiates heat back into the atmosphere (exactly the same as get from Sun) and CO2 acts as a barrier for the radiated heat from earth, retaining heat in the atmosphere and warming the planet. Why Greenhouse Gases Make the Planet Warmer: https://www.youtube.com/watch?v=AIBk0pGV_BQ https://www.youtube.com/watch?v=AIBk0pGV_BQ But, there are lots of other gases that have higher GWP. Fluorinated gases: Hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride are synthetic gases used for refrigeration (maybe other applications). Fluorinated gases replaced CFCs, which were causing ozone depletion. But they have high GWP. HFCs: up to 12,400, PFCs: up to 11,100, NF3: 16,100, SF6: 23,500 (https://www.epa.gov/ghgemissions/fluorinated-gas-emissions https://www.epa.gov/ghgemissions/fluorinated-gas-emissions) So, we have to find better alternatives for refrigerants. Because, these leak. And everybody on the planet is going to buy ACs. CO2 is a terrific refrigerant because it has GWP 1 and leaking of CO2 is perfectly okay. With 40 - 60 billion tons of CO2 from fossil fuels, CO2 leaks from refrigerants are less than a rounding error.
- roughly 1mo ago
  And also we have a large overabundance of CO2 we need to figure out something to do with, and using it in the heat pumps we’re all going to need to adjust to our overabundance of CO2 seems like a quite parsimonious arrangement.
danans 1mo ago
[dead]
Unified-Mentor 1mo ago
[dead]
Hasz 1mo ago
I am working on a 5-10 year design a house and desperately hope monoblock air to water heat pumps with r744 (co2) are mature in the US market then. There are some, but it is still niche. I am not a big fan of running lineset with r-410a or r32 in a confined space, too much risk of someone accidentally puncturing it. I would love hydronic systems to be more popular in the US. Being able to run hot/cold water in pex is stupid easy in both new construction and cheap in labor/materials. no noise concerns like forced air and much better routing for MEP imo. combined with an ERV, you can build a very good, high effiency zoned system that is comfortable and flexible. Will see!
- forty 1mo ago
  Here in France there are also heat pump using R290 (propane) which has greenhouse effect close to R744
pvillano 1mo ago
There are also solar water heaters that are a bunch of black pipes on a roof. Napkin math based on Amazon/Home Depot prices You can get a 80"x90"x95% = 2kW output solar heater for $2000 or eight 45"x70"x25% = 1.8kW solar panels for $2800 A regular water heater needs about 12kWh a day, which is about what both systems would produce. However, a heat pump water heater is 4x as efficient, so you could get by with $700 of solar panels. Except, a heat pump water heater costs $2000 instead of $500 for a regular electric heater. There's also install, maintenance, and the fact that we're talking about grid prices, not home panels, but those won't fit on my napkin.
- turtlebits 1mo ago
  Solar water heaters (including evacuated vacuum tube) are great for efficiency, but PV has gotten so cheap and reliable that it's almost never worth a dedicated solar water heater unless you're extremely constrained for space.
  - frankus 1mo ago
    PV also (usually) lets you export generation in excess of what you're using, is ~immune to freezing, and can be pretty darned efficient if the PV is driving a heat pump.
- lostlogin 1mo ago
  > A regular water heater needs about 12kWh a day, For reference: I’m in a household of three. Over the last month (winter, when n case that matters) we averaged 7.9kwh per day. I recently did the maths on switching to a heat pump hot water cylinder and the payback was surprisingly long at 5-7 years.
goda90 1mo ago
Any electric or heat pump water heater that can have its thermostat digitally controlled could be combined with a thermostatic mixing valve hooked to the cold water line and used as a heat battery. When electricity is cheap/solar is producing have set the thermostat to the highest value it allows. Otherwise set it down to the the lowest comfortable value(~120F). The thermostatic mixing valve will mix the hot water with cold water to meet the comfortable value regardless of where it's at in the tank and the insulation will keep the water hot for hours after it's heated to the maximum.
- kalleboo 1mo ago
  The Japanese "EcoCute" heat pump water heaters like this one all work like that. Our very similar in specs Mitsubishi unit keeps the internal temperature at 80 C, and the electronic control panel in the bathroom/kitchen let you choose separate temperatures for bath water and hot tap water which it blends to match
fooblaster 1mo ago
can anyone recommend the best heat pump water heater for the us market?
- blackjack_ 1mo ago
  you have to put at least a little bit of context on asks like if you want a reply. Nobody knows how much water you use, how big of a house / apt, how many bathrooms, etc.
  - fooblaster 1mo ago
    It's open ended to solicit the advice of anyone who cares. But, given it didn't work, 80 gallon capacity / 2 bedrooms / 2 bathrooms
elromulous 1mo ago
Is "tariff" here used to mean "rate"?
- elromulous 1mo ago
  Answering my question https://en.wikipedia.org/wiki/Tariff_(regulation) https://en.wikipedia.org/wiki/Tariff_(regulation)
hobo123 1mo ago
I wonder if these could be dangerous if there is ever a leak releasing the CO2. I believe humans only tolerate very low concentrations in the air. Happy they named it EcoCute, that's so much better than ElectroCute :)
- elric 1mo ago
  Propane isn't exactly good for you either, and it'd obviously flammable. Freon caused ozone layer depletion. There is no perfect refrigerant, but CO2 seems pretty safe.
immy 1mo ago
For those in US looking for this today, see Sanco2 (and Harvest Thermal for water to air or radiant heat)
tito 1mo ago
For those of you with a one track mind like me: each CO2 heat pump uses <10 pounds of CO2, roughly the carbon dioxide emissions from driving 10 miles. So no, switching everyone to a CO2 heat pump will not magically store all our emissions.
Havoc 1mo ago
Hitachi brings joy into the world
golem14 1mo ago
These devices should just have an API so that they can be controlled externally, e.g. by a home app. And maybe the EU could force a common API core for devices like this. e.g., I'd LOVE to have an API to have dryers/ other high current machines refuse to run if the grid is out and the house run on batteries.
thelastgallon 1mo ago
(Updating my previous note with insightful comments on this post) A heat pump conjures up an image of an appliance, but it is a principle of physics. Heat can be created by burning fuel or electric resistance. Cold can't be created. Cold is the lack of heat. Cold is 'created' by removing heat. Fridge keeps the inside cool by moving heat from inside and dumps it outside. This movement of heat is called a heat pump (pumping heat in a specific direction). If we can use a heat pump for creating cold, we can also create heat by pumping heat in the opposite direction. We always have heat in the environment until we get to 0 degree Kelvin. Which means we can have a heat pump water heater in the garage. Or a heat pump furnace. Creating heat from fuel/resistance is at most 100% efficient (most likely a LOT less). Heat pumps are 400% - 500% efficient per unit of electricity, because the idea is just to move heat. In one direction, or another. Indoor air quality is just as bad as outdoor air pollution, because we use natural gas for heating and cooking. Anything that burns creates particulate matter. Most homes are closed spaces, the particulate matter never escapes. Cooking can be done by induction, infrared or electric resistance. Heat pumps replace natural gas water heaters and furnaces. We don’t need to build natural gas pipeline infrastructure to every home, which probably costs million(s)/mile. Household energy bills are fragmented: 2 gas cars, natural gas for cooking, water heater and furnace, and electricity for everything else. EVs replace gas cars. Cooking by induction, and heat pumps replace heating appliances. Now, all the uses of energy are electric. Instead of spending ~$1000+ on 3 different types of energy bills, it creates a clear picture of total electricity consumption. This consolidation makes people think about their energy and how to make the bills disappear. Then they can install solar and make the entire energy bill zero. Forever. With heat pumps, we gain ~5X efficiency, solve indoor air pollution, save on natural gas infrastructure capex, make everything electric, and let people save money. While getting close to net zero. Heating and cooling are also very important for demand shifting. Because of thermal mass (and inertia), heating and cooling can be done when energy is cheapest (which is the cleanest source). If heating and cooling is all electric, smart appliances can connect to the grid and figure out when to use energy. The cost savings of going all electric are going to be significant. There is not only an immediate reduction, but with demand destruction, the price of oil is going to fall precipitously. Oil is priced at the margin, based on demand. If demand is high, people are willing to pay whatever price and costlier sources of extraction (shale, fracking, etc) become profitable. With low demand, Saudi Arabia can supply the world at $10/barrel. There is a small problem with heat pumps though. It's the refrigerant used to transfer the heat. These are mostly synthetic chemicals. Historically, these were Chlorofluorocarbons (CFCs). CFCs cause ozone depletion and have a high GWP of 14,400. What is GWP? CO2 is a warming gas that has Global Warming Potential (GWP) of 1 (the standard). Earth radiates heat back into the atmosphere (exactly the same as it gets from the Sun) and CO2 acts as a barrier for the radiated heat from earth, retaining heat in the atmosphere and warming the planet. Why Greenhouse Gases Make the Planet Warmer: https://www.youtube.com/watch?v=AIBk0pGV_BQ https://www.youtube.com/watch?v=AIBk0pGV_BQ But, there are lots of other gases that have higher GWP. Hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride are synthetic gases used for refrigeration (maybe other applications). These new engineered chemicals replaced CFCs, which were causing ozone depletion. But they have high GWP. HFCs: up to 12,400, PFCs: up to 11,100, NF3: 16,100, SF6: 23,500 (https://www.epa.gov/ghgemissions/fluorinated-gas-emissions https://www.epa.gov/ghgemissions/fluorinated-gas-emissions) HFOs break down and produce trifluoroacetic acid (TFA), which is a PFAS. PFAS rains back down, is a forever chemical and bioaccumulates. (vel0city: https://news.ycombinator.com/item?id=49645555 https://news.ycombinator.com/item?id=49645555) There are billions without ACs. They are all going to buy them. It is better if we figure out better refrigerants. And all refrigerants leak. These will cause problems. Many heating/cooling appliances need to be recharged with refrigerants once in a while. There seem to be several workable alternatives: CO2, isobutane, propane, ammonia. Water is used for district heating. In the middle-east, there is district cooling with water and ammonia. CO2 is a terrific refrigerant because it has GWP 1 and leaking of CO2 is perfectly okay. With 40 - 60 billion tons of CO2 from fossil fuels, CO2 leaks from refrigerants are less than a rounding error. Why aren’t we using CO2? (bronson: https://news.ycombinator.com/item?id=49645996 https://news.ycombinator.com/item?id=49645996) It's because CO2 has to be run at more extreme temperatures and pressures, fine for factory-made connections inside a single unit but a showstopper for field joints.
wffurr 1mo ago
The daytime energy shifting is interesting. I wonder if a heat pump water heater could have a variable tank temperature and then use thermostatic mixing valves at point-of-use to get consistent, safe temperatures from faucets and such. I can't be the first person to have thought of this. The article is really light on details for how the tariff-compatibility works, but perhaps it's something like this. I'm imagining a water tank that gets very hot during the daytime when energy is cheap and then slowly cools during peak cost hours or night (if linked to solar power), but remains above a usable temperature. Thermostatic mixing valves bring the very hot daytime temperature down to a safe usable temperature, but also allow the nighttime temperature to be usably hot as well.

321 points by thelastgallon 1mo ago

CO2 as a refrigerant isn't new: * https://en.wikipedia.org/wiki/R-744 https://en.wikipedia.org/wiki/R-744 It's just not as prevalent in the residential HVAC market (which this product serves?), and more in the commercial/industrial space (probably because of the higher pressures needed to get into a liquid state).

Lwerewolf 1mo ago
There are resident systems, and they're of exactly the type listed in the article (i.e. water heaters). Residential... area heating pumps, so to say, are moving towards propane (afaik). I've been looking into getting a propane monoblock air-to-water pump, with an antifreeze loop towards an indoors heat exchanger / water tank.
- adaml_623 1mo ago
  Trends for new refrigerant depends on country... some to R-454B, and some to Propane, doesn't seem like C02 is very common which is a pity because I love the idea of a non-toxic non-flammable super cheap refrigerant. This is for the Japanese market so perhaps the cons of the C02 systems are outweighed by the safety aspects.
alex_duf 1mo ago
It's useful though, as I think (correct me if I'm wrong) that the gases generally used in HVAC tends to have much worse warming effect than co2 per volume. We do need heat pumps deployed at large scale, but sometimes I worry we don't understand they need to be handled with care at the end of their life
- PunchyHamster 1mo ago
  If it is outside you can just use propane as refrigerant. Low warming value and it leaking to outside doesn't matter, not gonna catch on fire. There are indoor devices using propane but they generally come with caveat "must be installed on room at least this m3", precisely so if it leaks it doesn't get to density that allows explosion
  - jabl 1mo ago
    I believe there are propane using split AC systems where propane is used only in the outside unit. The outside unit has a heat exchanger transferring the heat to some glycol-water solution which is what then circulates through the inside unit.
  - 27183 1mo ago
    I currently have R410a heat pumps with minisplits, when they're off warranty sometime in the future I might consider putting propane in them. The main question would be whether the oil used with R410a is compatible with propane as a refrigerant. This is probably a little bit "dangerous" in the sense that I'll have high pressure propane in the line sets and minisplits inside the house, but it's a very small volume of propane and not really any more dangerous from a fire perspective than my propane fired condensing gas boiler. [edit] a little internet sleuthing indicates that hydrocarbon refrigerants "might be" compatible with basically any oil, so I can probably just continue using whatever oil is in it.
- moepstar 1mo ago
  Yes, that dangerous effect is indexed as GWP - global warming potential. CO2 has a GWP of 1 in this context, while other refrigerants are worse - for example, R32 has a GWP of 675 (so 675x worse if it escapes), not sure about R290 (Propane), which I believe is either about 40 or 14… Regarding EoL: At least around here, household appliances such as fridges are brought to a recycling yard and are properly taken care of in that regard… and as for heatpumps - those are only to be installed by certified professionals, for this very reason.
  - 1mo ago
arpinum 1mo ago
CO2 does better with large temp deltas, like hot water tanks. Radiators don't produce large deltas - the inlet to outlet diff is typically under 10 degrees. But they run at higher pressures, making the manufacturing more expensive.
deleted 1mo ago
[deleted]
totetsu 1mo ago
I heard CO2 is a gas with a powerful green house effect. What happens at the end of life of these units I wonder? What if they leak and it gets into the atmosphere!
- ErroneousBosh 1mo ago
  CO2 has a surprisingly feeble greenhouse effect. Almost anything else you could use as a refrigerant is worse. Even water vapour is a worse greenhouse gas. Edit: wait, have I been whooshed? Apologies if so... ;-)
  - Brian_K_White 1mo ago
    Maybe but at this point I no longer think it's fair to be quite this dry on something that quite so many people would be legitimately sincere about anyway so I wouldn't exactly apologize for being the victim.
    - ErroneousBosh 1mo ago
      > Maybe but at this point I no longer think it's fair to be quite this dry on something that quite so many people would be legitimately sincere about Yeah, but I'm from the UK so I should be able to detect dry humour. It's something that Americans don't really get. You know, like affordable healthcare.
      - totetsu 1mo ago
        I apologise, I am at the dry humour stage of climate grief.
        ErroneousBosh 1mo ago
        Take heart in the thought that this is going to ease off a bit in a couple of years when the current solar cycle dies down and the sun is not dumping about 5% more energy into the atmosphere than normal.
JTbane 1mo ago
There is no reason not to use propane or butane, they have low global warming potential and is cheap. The fire risk is overstated, no one thinks twice about carrying a lighter in their pocket.
pjc50 1mo ago
This has the useful property of being regulation-exempt because it's already literally everywhere. Unlike "F gases", which have much more serious greenhouse effects and are regulated in the UK (and elsewhere): https://www.gov.uk/government/collections/fluorinated-gas-f-gas-guidance-for-users-producers-and-traders https://www.gov.uk/government/collections/fluorinated-gas-f-... You could install your own CO2-based heat pump in a way you wouldn't be allowed to do with a F-gas based one.
- bluGill 1mo ago
  OTOH, CO2 uses much higher pressures and so I'm more willing to DIY a F-gas based one. CO2 if there is a leak can cut a limb off. F-gas is generally not that high. I wouldn't want a leak/mistake, but CO2 is less personally forgiving.

objektif 1mo ago

“Hitachi has not yet disclosed full efficiency specifications for the two new models. Their predecessors, the BHP-FV37WD and BHP-FV46WD, have annual hot-water and heat-retention efficiency ratings under Japanese Industrial Standards (JIS) of 4.2 and 4.1, respectively.” What does this mean?

alex_duf 1mo ago
If I'm not mistaken, it means 1kWh of electricity moves 4.1kWh of heat into your hot water tank. Heat pumps are amazing.
- PunchyHamster 1mo ago
  well, in case of water heater it moves it from your room to the water. Which means in winter that is extra work for your heating system to compensate for But in climates where heating only really runs in winter it's great
  - Danoch 1mo ago
    [dead]
  - slau 1mo ago
    Technology Connections has recently published an in-depth piece of the advantages and disadvantages of in-room heat-pump water heaters [1]. The tl;dw is that it is significantly slower than a resistive or gas-powered water heater, and lowers the temperature of the room by a few degrees, but nothing major. You have to over-provision them compared to your needs. And they are way bigger. [1]: https://youtu.be/F_7B2shTPPU https://youtu.be/F_7B2shTPPU
    - cogman10 1mo ago
      > significantly slower than a resistive or gas-powered water heater This was TC being a weirdo. He bought a 120V hot water heater. Had he done a regular 240V water heater the recovery time would be comparable to pure resistive water heaters. But the takeaway about cooling is important. These things barely chill the room they are in.

elgertam 1mo ago

> Some Japanese utilities have introduced tariffs designed to encourage daytime water heating as growing volumes of solar generation enter the grid. [Emphasis added.] I was quite confused at the use of "tariff" here, as it meant to me a "tax on a good crossing a political boundary." Turns out, 'tariff' has an older meaning: a published schedule of fees or taxes issued by some authority.

Aboutplants 1mo ago
US utilities also have Tariffs. It’s the statement of how the utility operates and charges users for service. Anytime a utility needs to adjust costs/rates, they need to file a Rate Case with the public utility commissions, and resulting in changes to the Tariff.
_joel 1mo ago
I've seen 'tariff' used a fair amount here in the UK on price lists (taxi etc)
- world2vec 1mo ago
  Same in Portugal: a "tarifa" can mean a price charged for a rendered service or a tax on imported products.
koito17 1mo ago
The Japanese word used in the context of price lists would be something like 料金表 or 料金メニュー. When I see "tariff", my mind only thinks of 関税 , and I was just as confused as you were. Turns out its just an item in a price schedule.
myrmidon 1mo ago
It's an arab loan word for ~"price list" (originally strongly suggesting an import-duty-like meaning). The same word exists in e.g. German or Italian, but mostly just means "pricing scheme" there, like in the article ("import duty" using a different expression in those languages). Might be a mostly/somewhat "false friend" for a German (pv magazine is german).

EspadaV9 1mo ago

I'm actually in need of a new hot water tank and have been looking for a heat pump one. Wonder if these will be available in Australia, and how they compare to the current range.

XorNot 1mo ago
I have a heat pump hot water unit in Australia - Sanden: https://www.sanden-hot-water.com.au/ https://www.sanden-hot-water.com.au/ CO2 refrigerant as well.
- masterj 1mo ago
  I have this one in Canada. Works well! But having water leave the building envelope is a bit scary on very cold days. There are heat traces and freeze valves so it should be fine, but I do worry about power outages during cold snaps
kalleboo 1mo ago
The Australian electronics YouTuber Dave Jones (EEVBlog) had a heat pump water heater installed in his house, and while on the outside it was branded "Reclaim Energy", it had a Made in Japan sticker and was internally a Mitsubishi.

boringg 1mo ago

Japan is so far ahead the rest of the world for quality and innovative heat pumps. Quiet, robust, high efficiency in cold climates. I wish they could bring the prices down though. I worry in 15 years we will all have crapily made Chinese heat pumps for a fraction of the cost. Noisy, not robust, copying competitor designs not innovating, lower efficiency but easily replaceable. Theres probably an analogy here with software talent and AI but its too early to do that.

deleted 1mo ago
[deleted]
PaulHoule 1mo ago
Not everything from China is crap. I'm a big fan of Chinese lenses. I reach for Japanese and German lenses when I want to take the highest quality photographs that look like the photographs all the other photographers take. When I want to take a picture like you've never seen before I reach for https://www.venuslens.net/product/laowa-9mm-f-5-6-ff-rl/?srsltid=AfmBOoppl0TfZiNVsfcMVy6cFS8xNhW0P7EmU4mgd2vanELacSrGxUmj https://www.venuslens.net/product/laowa-9mm-f-5-6-ff-rl/?srs... or https://findingrange.com/2022/01/14/7artisans-photoelectric-50mm-f0-95-lens-review/ https://findingrange.com/2022/01/14/7artisans-photoelectric-... It's true a $3000 lens from Sony has better optical quality than a $300 lens from China, like take a picture of a starry sky and you will see light rays bounce around a lot more inside the Chinese lens. But in terms of value and innovation Chinese lenses have a place, and many Chinese manufacturers are looking for this kind of opportunity for whatever they make.
- post_break 1mo ago
  China figured out how to make thermal imaging sensors as well. Why would you buy a $4,000 Flir with less resolution when you can get a $400 Topdon. What's funny is now it appears Flir has cut their prices dramatically to compete.
- 27183 1mo ago
  I have Haier Arctic heat pumps that are made in China. They've been great so far. I've also worked with suppliers in Shenzhen for one-off custom electronic devices that would put western companies to shame in their communication, efficiency, turnaround time, cost, and engineering quality. The new transmission I just put in my truck was made in China too.

kalleboo 1mo ago

I live in Japan and last year when we moved from an apartment to a house we installed a Mitsubishi EcoCute heat pump water heater which already has these features and is also a CO2 heat pump. We have one of the "all-denka" electric plans, where we trade off cheap rates during solar hours for expensive rates during duck curve hours. By having the hot water only run during cheap hours, and having the aircon turned off/down during the expensive hours, we're paying less in energy for our all-electric house than we did in combined electric+gas in our 3x smaller apartment. We pay approx (before fees, and the rates change slightly by season): * 8 AM - 10 AM: 35 yen/kWh * 10 AM - 4 PM: 13 yen/kWh * 4 PM - 6 PM: 35 yen/kWh * 6 PM - 8 AM: 19 yen/kWh Our Mitsubishi has other nice features like it can recirculate the water in the bath through a heat exchanger after you already filled it and got in, so it will keep the water from cooling down to lukewarm, and you can even adjust the bath water temperature if you ended up with filling it with too warm or too cold water. Of course, there's also an app so you can start filling up the bathtub when you leave work for home so a hot bath is waiting for you. There's also an intercom to the kitchen "so mom can tell the kids to get out of the bath, dinner is ready". edit: the wifi integration does have one actually useful feature: if we had solar panels, then it can use data from them to know when to run "for free", and it can use weather data to predict if it should wait for sun or not to run

koolba 1mo ago
> Our Mitsubishi has other nice features like it can recirculate the water in the bath through a heat exchanger after you already filled it and got in, so it will keep the water from cooling down to lukewarm, and you can even adjust the bath water temperature if you ended up with filling it with too warm or too cold water. How long do you sit in a bath? > Of course, there's also an app so you can start filling up the bathtub when you leave work for home so a hot bath is waiting for you. My immediate reaction to this is, “there’s a way for my house to be remotely flooded”.
- kalleboo 1mo ago
  > How long do you sit in a bath? We love our baths here in Japan > My immediate reaction to this is, “there’s a way for my house to be remotely flooded”. I forgot to mention that it senses and automatically stops filling the bath at a select number of liters, even if you start a bath using the physical button when you're at home.

nickpeterson 1mo ago

I live in Ohio in a 100 year old home with cast iron radiators and a natural gas boiler and a gas water heater. I’d love to move to electric but it feels like my only real option for keeping the cast iron is something like the Daikin Altherma 3 H HT. Does anyone more knowledgeable of this part of the industry know of any reasonable alternatives for electrifying old houses but keeping the radiators?

ErroneousBosh 1mo ago
Underfloor heating works best with air source heat pumps, so just switch to that. Then run a wee bit hot water through your cast iron rads for the look of the thing.
- nickpeterson 1mo ago
  I take your point, but what you’re describing would have to cost thousands just in putting in underfloor pipes. It will never make financial sense to do it? Or am I misinterpreting your suggestion?
  - jabl 1mo ago
    I don't see how installing underfloor heating in an existing house can make economic sense. Additionally in older houses the windows tend to be a bit leaky, so the radiators being under the windows is important to prevent unpleasant cold drafts. Yes, the heat pump will take an efficiency hit for using radiators rather than underfloor heating. I'd say that's just part of the cost of living in an old house.
Aboutplants 1mo ago
Don’t forget to include the natural gas utility distribution costs when calculating any potential financial benefit when looking to switch to fully electric. Your not only getting rid of the natural gas Energy costs, but since your in Ohio, I’d wager your actual Distribution costs for your natural gas supply is actually greater than your actual Natural gas energy Supply costs. Reducing to simply one utility distribution cost will help substantially when looking at long term financial viability

deleted 1mo ago

[deleted]

thelastgallon 1mo ago

Some background info for context. (for those that may not be familiar). Heat pump conjures up an image of an appliance, but it is a principle of physics. Heat can be created by burning fuel or electric resistance. Cold can't be created. Cold is the lack of heat. Cold is 'created' by removing heat. Fridge keeps the inside cool by moving heat from inside and dumps it outside. This movement of heat is called heat pump (pumping heat in a specific direction). If we can do this for cold, we can also do this for heat. After all, we always have heat in the environment until we get to 0 degree Kelvin. Which means we can have heat pump water heater in the garage. Or heat pump furnace. Creating heat from fuel/resistance is at most 100% efficient (most likely a LOT less). Heat pumps are 400% - 500% efficient per unit of electricity, because the idea is just to move heat. In one direction, or another. All of this is great, until we get to the refrigerant used to transfer the heat. These are very specific chemicals. Mostly synthetic chemicals. Historically, these were Chlorofluorocarbons (CFCs). CFCs caused ozone depletion and have high GWP of 14,400. What is GWP? CO2 is a warming gas that has Global Warming Potential (GWP) of 1 (the standard). Earth radiates heat back into the atmosphere (exactly the same as get from Sun) and CO2 acts as a barrier for the radiated heat from earth, retaining heat in the atmosphere and warming the planet. Why Greenhouse Gases Make the Planet Warmer: https://www.youtube.com/watch?v=AIBk0pGV_BQ https://www.youtube.com/watch?v=AIBk0pGV_BQ But, there are lots of other gases that have higher GWP. Fluorinated gases: Hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride are synthetic gases used for refrigeration (maybe other applications). Fluorinated gases replaced CFCs, which were causing ozone depletion. But they have high GWP. HFCs: up to 12,400, PFCs: up to 11,100, NF3: 16,100, SF6: 23,500 (https://www.epa.gov/ghgemissions/fluorinated-gas-emissions https://www.epa.gov/ghgemissions/fluorinated-gas-emissions) So, we have to find better alternatives for refrigerants. Because, these leak. And everybody on the planet is going to buy ACs. CO2 is a terrific refrigerant because it has GWP 1 and leaking of CO2 is perfectly okay. With 40 - 60 billion tons of CO2 from fossil fuels, CO2 leaks from refrigerants are less than a rounding error.

roughly 1mo ago
And also we have a large overabundance of CO2 we need to figure out something to do with, and using it in the heat pumps we’re all going to need to adjust to our overabundance of CO2 seems like a quite parsimonious arrangement.

danans 1mo ago

[dead]

Unified-Mentor 1mo ago

[dead]

Hasz 1mo ago

I am working on a 5-10 year design a house and desperately hope monoblock air to water heat pumps with r744 (co2) are mature in the US market then. There are some, but it is still niche. I am not a big fan of running lineset with r-410a or r32 in a confined space, too much risk of someone accidentally puncturing it. I would love hydronic systems to be more popular in the US. Being able to run hot/cold water in pex is stupid easy in both new construction and cheap in labor/materials. no noise concerns like forced air and much better routing for MEP imo. combined with an ERV, you can build a very good, high effiency zoned system that is comfortable and flexible. Will see!

forty 1mo ago
Here in France there are also heat pump using R290 (propane) which has greenhouse effect close to R744

pvillano 1mo ago

There are also solar water heaters that are a bunch of black pipes on a roof. Napkin math based on Amazon/Home Depot prices You can get a 80"x90"x95% = 2kW output solar heater for $2000 or eight 45"x70"x25% = 1.8kW solar panels for $2800 A regular water heater needs about 12kWh a day, which is about what both systems would produce. However, a heat pump water heater is 4x as efficient, so you could get by with $700 of solar panels. Except, a heat pump water heater costs $2000 instead of $500 for a regular electric heater. There's also install, maintenance, and the fact that we're talking about grid prices, not home panels, but those won't fit on my napkin.

turtlebits 1mo ago
Solar water heaters (including evacuated vacuum tube) are great for efficiency, but PV has gotten so cheap and reliable that it's almost never worth a dedicated solar water heater unless you're extremely constrained for space.
- frankus 1mo ago
  PV also (usually) lets you export generation in excess of what you're using, is ~immune to freezing, and can be pretty darned efficient if the PV is driving a heat pump.
lostlogin 1mo ago
> A regular water heater needs about 12kWh a day, For reference: I’m in a household of three. Over the last month (winter, when n case that matters) we averaged 7.9kwh per day. I recently did the maths on switching to a heat pump hot water cylinder and the payback was surprisingly long at 5-7 years.

goda90 1mo ago

Any electric or heat pump water heater that can have its thermostat digitally controlled could be combined with a thermostatic mixing valve hooked to the cold water line and used as a heat battery. When electricity is cheap/solar is producing have set the thermostat to the highest value it allows. Otherwise set it down to the the lowest comfortable value(~120F). The thermostatic mixing valve will mix the hot water with cold water to meet the comfortable value regardless of where it's at in the tank and the insulation will keep the water hot for hours after it's heated to the maximum.

kalleboo 1mo ago
The Japanese "EcoCute" heat pump water heaters like this one all work like that. Our very similar in specs Mitsubishi unit keeps the internal temperature at 80 C, and the electronic control panel in the bathroom/kitchen let you choose separate temperatures for bath water and hot tap water which it blends to match

fooblaster 1mo ago

can anyone recommend the best heat pump water heater for the us market?

blackjack_ 1mo ago
you have to put at least a little bit of context on asks like if you want a reply. Nobody knows how much water you use, how big of a house / apt, how many bathrooms, etc.
- fooblaster 1mo ago
  It's open ended to solicit the advice of anyone who cares. But, given it didn't work, 80 gallon capacity / 2 bedrooms / 2 bathrooms

elromulous 1mo ago

Is "tariff" here used to mean "rate"?

elromulous 1mo ago
Answering my question https://en.wikipedia.org/wiki/Tariff_(regulation) https://en.wikipedia.org/wiki/Tariff_(regulation)

hobo123 1mo ago

I wonder if these could be dangerous if there is ever a leak releasing the CO2. I believe humans only tolerate very low concentrations in the air. Happy they named it EcoCute, that's so much better than ElectroCute :)

elric 1mo ago
Propane isn't exactly good for you either, and it'd obviously flammable. Freon caused ozone layer depletion. There is no perfect refrigerant, but CO2 seems pretty safe.

immy 1mo ago

For those in US looking for this today, see Sanco2 (and Harvest Thermal for water to air or radiant heat)

tito 1mo ago

For those of you with a one track mind like me: each CO2 heat pump uses <10 pounds of CO2, roughly the carbon dioxide emissions from driving 10 miles. So no, switching everyone to a CO2 heat pump will not magically store all our emissions.

Havoc 1mo ago

Hitachi brings joy into the world

golem14 1mo ago

These devices should just have an API so that they can be controlled externally, e.g. by a home app. And maybe the EU could force a common API core for devices like this. e.g., I'd LOVE to have an API to have dryers/ other high current machines refuse to run if the grid is out and the house run on batteries.

thelastgallon 1mo ago

(Updating my previous note with insightful comments on this post) A heat pump conjures up an image of an appliance, but it is a principle of physics. Heat can be created by burning fuel or electric resistance. Cold can't be created. Cold is the lack of heat. Cold is 'created' by removing heat. Fridge keeps the inside cool by moving heat from inside and dumps it outside. This movement of heat is called a heat pump (pumping heat in a specific direction). If we can use a heat pump for creating cold, we can also create heat by pumping heat in the opposite direction. We always have heat in the environment until we get to 0 degree Kelvin. Which means we can have a heat pump water heater in the garage. Or a heat pump furnace. Creating heat from fuel/resistance is at most 100% efficient (most likely a LOT less). Heat pumps are 400% - 500% efficient per unit of electricity, because the idea is just to move heat. In one direction, or another. Indoor air quality is just as bad as outdoor air pollution, because we use natural gas for heating and cooking. Anything that burns creates particulate matter. Most homes are closed spaces, the particulate matter never escapes. Cooking can be done by induction, infrared or electric resistance. Heat pumps replace natural gas water heaters and furnaces. We don’t need to build natural gas pipeline infrastructure to every home, which probably costs million(s)/mile. Household energy bills are fragmented: 2 gas cars, natural gas for cooking, water heater and furnace, and electricity for everything else. EVs replace gas cars. Cooking by induction, and heat pumps replace heating appliances. Now, all the uses of energy are electric. Instead of spending ~$1000+ on 3 different types of energy bills, it creates a clear picture of total electricity consumption. This consolidation makes people think about their energy and how to make the bills disappear. Then they can install solar and make the entire energy bill zero. Forever. With heat pumps, we gain ~5X efficiency, solve indoor air pollution, save on natural gas infrastructure capex, make everything electric, and let people save money. While getting close to net zero. Heating and cooling are also very important for demand shifting. Because of thermal mass (and inertia), heating and cooling can be done when energy is cheapest (which is the cleanest source). If heating and cooling is all electric, smart appliances can connect to the grid and figure out when to use energy. The cost savings of going all electric are going to be significant. There is not only an immediate reduction, but with demand destruction, the price of oil is going to fall precipitously. Oil is priced at the margin, based on demand. If demand is high, people are willing to pay whatever price and costlier sources of extraction (shale, fracking, etc) become profitable. With low demand, Saudi Arabia can supply the world at $10/barrel. There is a small problem with heat pumps though. It's the refrigerant used to transfer the heat. These are mostly synthetic chemicals. Historically, these were Chlorofluorocarbons (CFCs). CFCs cause ozone depletion and have a high GWP of 14,400. What is GWP? CO2 is a warming gas that has Global Warming Potential (GWP) of 1 (the standard). Earth radiates heat back into the atmosphere (exactly the same as it gets from the Sun) and CO2 acts as a barrier for the radiated heat from earth, retaining heat in the atmosphere and warming the planet. Why Greenhouse Gases Make the Planet Warmer: https://www.youtube.com/watch?v=AIBk0pGV_BQ https://www.youtube.com/watch?v=AIBk0pGV_BQ But, there are lots of other gases that have higher GWP. Hydrofluorocarbons, perfluorocarbons, sulfur hexafluoride, and nitrogen trifluoride are synthetic gases used for refrigeration (maybe other applications). These new engineered chemicals replaced CFCs, which were causing ozone depletion. But they have high GWP. HFCs: up to 12,400, PFCs: up to 11,100, NF3: 16,100, SF6: 23,500 (https://www.epa.gov/ghgemissions/fluorinated-gas-emissions https://www.epa.gov/ghgemissions/fluorinated-gas-emissions) HFOs break down and produce trifluoroacetic acid (TFA), which is a PFAS. PFAS rains back down, is a forever chemical and bioaccumulates. (vel0city: https://news.ycombinator.com/item?id=49645555 https://news.ycombinator.com/item?id=49645555) There are billions without ACs. They are all going to buy them. It is better if we figure out better refrigerants. And all refrigerants leak. These will cause problems. Many heating/cooling appliances need to be recharged with refrigerants once in a while. There seem to be several workable alternatives: CO2, isobutane, propane, ammonia. Water is used for district heating. In the middle-east, there is district cooling with water and ammonia. CO2 is a terrific refrigerant because it has GWP 1 and leaking of CO2 is perfectly okay. With 40 - 60 billion tons of CO2 from fossil fuels, CO2 leaks from refrigerants are less than a rounding error. Why aren’t we using CO2? (bronson: https://news.ycombinator.com/item?id=49645996 https://news.ycombinator.com/item?id=49645996) It's because CO2 has to be run at more extreme temperatures and pressures, fine for factory-made connections inside a single unit but a showstopper for field joints.

wffurr 1mo ago

The daytime energy shifting is interesting. I wonder if a heat pump water heater could have a variable tank temperature and then use thermostatic mixing valves at point-of-use to get consistent, safe temperatures from faucets and such. I can't be the first person to have thought of this. The article is really light on details for how the tariff-compatibility works, but perhaps it's something like this. I'm imagining a water tank that gets very hot during the daytime when energy is cheap and then slowly cools during peak cost hours or night (if linked to solar power), but remains above a usable temperature. Thermostatic mixing valves bring the very hot daytime temperature down to a safe usable temperature, but also allow the nighttime temperature to be usably hot as well.