Oxford study proves heat pumps triumph over fossil fuels in the cold
nationalobserver.com
nationalobserver.com
During winter in Greenland, it's totally accepted to leave your car engine running at all times. Why? Because it's likely your diesel supply will freeze up otherwise.
The initial rollout of EVs in Greenland was a disaster. Fine during boring season (as summer is known locally: you can't go out and hunt properly!), but useless most of the year: the batteries would just die.
Then, EVs with built-in heat pumps became available, to aid with cabin temperature (mostly) but also very-cold-weather startup performance (coincidentally). These worked pretty well: when parked, the heat pump would supply warm-ish air to the batteries, which would then continue to feed the heat pump, and work with a properly charged power pack the next day.
So, instead of diesel cars idling 24/7, new EVs now run at, say, 80% efficiency in Greenland. Not a huge deal, globally speaking, but still a nice win.
For instance, the battery charges really poorly when it's cold, diesel crystals can form in the diesel filter, even if the fuel is technically liquid, and the engine is really inefficient if it's too cold.
Of these, the battery not charging properly, coupled with a lot more electricity needed to start the engine when cold, is probably the first one you will encounter. If it's -20C, you may have to charge the battery once every few days using an external charger, if you mostly do short to medium trips.
I live in Norway, were we can get quite cold weather too, and the typical remedy is some kind of engine heater, fueled either by electricity or by the car's own fuel (for newer models, mostly).
There are several types of heating elements, some heat the cooliant (heatiant during winter), some heat the engine oil, and some just heat the underside of the car. All can contribute really well to the problems you get down to -40C or a bit below, at least if they provide enough power (some may be underpowered if the car is exposed and it's really cold) I think these will melt crystals forming in the diesel filter, and once the engine is started, diesel will circulate through the engine, ensuring that the fuel in the tank reaches an acceptable temperature sooner. Also, a warmer engine requires a lot less electricity to start, meaning battery issues are less likely.
While I don't think most of these are designed to heat the fuel tank directly, they probably generate enough heat that some of the heating will spill to the fuel, too, especially if the car is sheltered in a garage.
And if the temperature outside falls well below -40C, you can probably heat the garage using a lot less energy than required to keep the engine running.
Keeping the engine running 24/7 in any location where electricity is available, doesn't seem like an efficient solution unless you're deep in Siberia and fuel is subsidized but electricity is not.
Around the places I've known (not Vancouver. Vancouver is special) - Diesel gets idled, and starting back up is careful. - Propane gets idled -35C and below and hopes it won't shut down. - Gas tends towards long startups but unless it's been left out all day without a block heater, it'll probably be fine. - Natural gas tends to need idling as per Diesel.
I've no experience with EVs though. But with lack of charging infrastructure throughout most of the Canadian prairies, it might be a while before it's a workable option here.
i'm certain i'm overlooking something, because it's not like cars are generating heat to be reflected by a tarp, unless you mean a driven car, thus warm, covered by a tarp, would maintain its heat longer in -50c ?
Story: One time a friend of mine got a hold of a diesel water heater used for semitrucks. I figured out how to get it running and then he used it a few times to build ghetto hot tubs in the snow.
You live in Ilulissat? Have fun driving between the harbor and the airport (all of the 20-or-so miles). And people do, but they tend to be taxi drivers, and they mostly drive EVs these days, again, not because of the actual cost of the vehicles.
Now, if you want to go anywhere in Greenland, you need a boat. And a sled and some dogs, or, if you insist, a snowmobile.
There is a smaller system that can consume diesel slowly and keep your fuel from freezing -- one doesn't have to run the entire engine!
The defrost specifications are also worth thinking about. Having your heat turn off for a few minutes to do a defrost cycle can be annoying if you only have one unit.
Low temperature means only a couple of degrees higher than ambient. It just constantly radiates. That also mean that heat pump needs to work less hard.
It does require a significant amount of insulation to ensure you don't lose the heat immediately.
And because of the high mass it means that interruptions aren't noticed.
In the north of the country you end up heating your house for some days with resistive heating, but it is still cheaper than any alternative source.
Heat pumps aren't that powerful. To enjoy it to its fullest you must have a well-insulated house, and ideally low-temperature floor heating.
That way the insulation and floor's volume provide the buffer for when your heat pump is defrosting.
So getting a heat pump without insulation is not smart.
Then there's the cost. A gas heater is 3 times as cheap, and for that price, 3 times as expensive.
Lastly, there's the issue of when it's really cold and the heat pump cannot extract heat from the outside air (this is much less a problem when you have an water to water heat pump, but they are significantly more expensive). Then the thing just runs on electricity. And that can be VERY expensive in certain parts of the worlds.
So we need incentives for insulation first. Then heat pumps. And probably electricity plans that a cold month isn't insanely more expensive.
Is 18 kW not enough? https://thermia.com/products/ground-source-heat-pumps/thermi...
Air-water heatpumps are available in ~9kW
> Then there's the cost. A gas heater is 3 times as cheap, and for that price, 3 times as expensive.
Only really a thing if there's a local gas network and subsised gas.
> Lastly, there's the issue of when it's really cold and the heat pump cannot extract heat from the outside air (this is much less a problem when you have an water to water heat pump, but they are significantly more expensive). Then the thing just runs on electricity. And that can be VERY expensive in certain parts of the worlds.
They work fine in -25c. Few people in the world live in places that are regularly colder than that for significant chunks of time.
Depends on the rest of your system. Our gas combi outputs 36kw on demand. We use high temperature rads and need no water storage.
To get premium performance from heat pumps you need buffet tanks to heat up water over the day and a low temperature central heating system.
All achievable, but it turns a £10k boiler installation into a £30k house-wide replumb. Well before you factor in actually making the house perform better. It takes a big run up to make the sums work.
https://www.theheatinghub.co.uk/why-our-condensing-boilers-d...
> The boiler does not reach 90%+ efficiencies until the return temperatures are around 45°C. This means water must exit the boiler at a maximum of 65°C, impart 20°C of heat to the room via the radiators, and return at 45°C.
edit: and if you read further they suggest that oversized boilers like yours have further efficiency losses:
> When boilers fire up, they automatically ramp up to 70% of their maximum output. For a 21kW boiler (common is most homes) this would be around 15kW. Given that only 6kW is needed on a very cold day, the boiler is always going to overheat the system. When the radiators cannot get rid of enough heat the return temperatures to the boiler are too high for it to condense.
Even down at -30°C it has a heat transfer capacity of 2.5 kW.
You didn't say how much your has heater costs so I have no idea how this compares but it seems reasonably priced to me.
I'd really like to have a plumber be able to install a mono block heat pump since the labour costs to install a heat pump look like highway robbery.
We need more Europeans to come open businesses here installing these!
What's the limiting parameter here? Obviously heat pumps can be scaled up to arbitrary sizes - I've used unimaginably large ones in the chemical industry. Do you mean power vs cost compared to other options? Power vs volume? Power vs. weight?
Stockholm has a couple 40 megawatt heat pumps as part of a set of just seven heat pumps which provide building heat to an entire district of the city, pumping heat through 3000 kilometers of pipes.
The only limiting factor I'm aware of for most commercially-available home heat pumps is that they tend not to work well below a certain temperature. This minimum temperature can be lowered by increasing the size of the outdoor radiator and adjusting the pump and coolant pressures to match.
https://www.irs.gov/credits-deductions/energy-efficient-home...
I would think someone with the right math skills would be able to build something like a base trap to absorb most of the energy in those frequency bands, though.
Daily incident shortwave energy per square meter is significantly lower in the winter (about half of what it is in the summer). You're also not going to get much of a current when the solar panels are buried in snow.
Wood burning stoves are cheap enough and the odds of you losing power to warrant needing one are large enough that it's a safer bet getting one.
Listen to your neighbors.
Not at all, I live in a rural area.
>For some remote regions, blizzards taking out the electrical grid is a real concern.
Effectively every fossil fuel powered heater being installed requires electricity for the fans to work.
>You need a local mechanism to generate heat and an on-site propane/oil tank is the only realistic option.
A backup generator that runs on propane. You'd need a backup generator to begin with even for propane heating, so just go full electric with a heat pump.
I'm all for electrifying things, but I wouldn't bet my life on them.
[1] https://en.wikipedia.org/wiki/December_2022_North_American_w...
Just... what happened to the meanest part of self-criticism that science bodies used to have? Do they think other people won't ask questions? Because I'm sorry, they do so a great deal more now than ever. Many of those "questions" are stupid. But some are not, and shouting them all down means people should distrust you.
When I've looked at one for my home to replace a 24kW gas boiler, all I can find is 14kW kits. Am I missing something? Can I not match the output of a big gas boiler?
You're right, it can't match the _peak_ output, but the whole system is designed so this isn't necessary.
With a "traditional" combi-boiler, it will turn on occasionally to heat the water in the central heating system, and continue to pump it around. When you need hot water, it switches over the heat-exchanger to directly heat the incoming water and this is when it will ramp up and burn the most gas (24kW+).
For an air-to-water heat pump system, the system will be on almost continually, but will heat the water to a lower temperature, the peak power output is less, but it averages out the same. For hot water, the system will heat a storage cylinder.
One of the catches here is that's it not always an easy retrofit as the lower water temperature can necessitate larger radiators.
https://www.heatgeek.com/do-i-need-to-upgrade-my-radiators-f...
edit: In-depth geeky video on this:
https://protonsforbreakfast.wordpress.com/2022/04/05/what-si...
Not sure why the market has moved this way but it is what it is. That unit probably is underspeced
https://carbonswitch.com/heat-pump-water-heater-buyers-guide...
IIRC It was basically using normal gas engine to move the coolant around but it also used heat produced by engine to heat the coils on the cold side so it was getting essentially more than 100% efficiency out of gas.
But it was even more expensive than traditional heat pump.
And not just new installs, but for existing work/ upgrades.
It's a 2-for, in that price increases and reliability decreases, since the gas grid now requires the (remote) electric grid to work.
I remember some fridge manual where it said minimum room size because they basically did the calculation "if it escapes and room is at least that big, it won't be stoichometric mixture and cause masssive explosion.
I also heard rumours people with old cars that had AC running on freon use it as replacement...
I guess they can just freeze then?
> he said it also stresses the need for more supports for low-income people to install heat pumps to save money and limit emissions.
That doesn't take into account the transfer loss or the cost of producing an maintaining all that gear.
In places where the vast majority of electricity comes from renewables or nuclear and where the supply is quite stable, heat pumps still make sense in cold weather. But using lignite based power plants to fuel heat pumps in Eastern Europe is something that is attractive more because it lets you heat buildings in highly populated areas while having the air pollution happen far away from population centers.
The smallest boiler is 25kw/hr while residential heat pumps are tiny as compared. Maybe 2-3-5kw/hr output.
The way it was put to me, there is no way the heat pump will output so much heated water to heat the house.
I could be missing something here.
In terms of BTUs, residential radiator boilers are like 40k BTU, I don't think heat pumps can output so much
25kw/hr boiler isn't working all the time. That boiler is also often sized to just heat a lot of water for shower/etc so the power is oversized "just" for heating house.
So during normal work the gas boiler will be cycling , while heat pump with lower power is just constantly heating the buffer and then heat from that buffer is used for heating the house.
For a buffer to work, it necessarily needs to be hotter than supply temperature, which means more losses and more work for the heat pump.
Since heat pump can easily adjust the supply temperature, the most efficient system will be the one where the energy delivered to underfloor heating or radiators is just balanced out by heat loss of the building.
Where buffers are useful is heat sources whose power cannot be modulated (my old diesel furnace for example- when it fired, it produced roughly 20kW, with the only adjustment being supply temperature at which it turns off), or where there is a cost to frequent starting/stopping the heat source (I.e. you probably don't want to get up in the middle of night to add wood to a wood-fired furnace, and pellet-fired furnace needs to be maintained more often in such operation mode).
If one really needs 25kW heat source, one really needs a 25kW heat source. There is no clever way around it. The real question is whether one really needs 25kW heat source (which can be answered definitively by either measuring the delivered==required power, looking at the peak continuous fuel consumption (let's say the coldest day or week), or by having accurate heat loss model of the building. In a heating season, the buffer cannot realistically be large enough to significantly reduce the power requirement. For example, 1m3 of hot water when used as a buffer can store roughly 30kWh (when heated 25 degC above supply temperature). My house needed 240kWh of energy in the coldest day, so the buffer would only cover 10% of the needed heat.
I had set up monitoring for my diesel furnace, so I could see for myself what was the peak heat requirement over two heating seasons (10kW continuous in the coldest winter day). So, I selected an 11kW heat pump, which, if needed also has 9kW of resistive backup heaters. It also matched the numbers in energy-efficiency certificate of the house (theoretical calculation based on materials/thickness/local outside temperatures) within 10-15% or so.
The buffer is there so the heat pump doesn't have to cycle or throttle but can work with maximum efficiency as long as possible. That is all. It is not there to heat your house for next few hours. I think newer ones that have throttling can just work with hydraulic clutch.
But the biggest difference is that heat pumps really want that more flow with lower temperature situation (as of course efficiency drops with the temperature), so you really want to have either higher area heaters or floor heating.
> Since heat pump can easily adjust the supply temperature, the most efficient system will be the one where the energy delivered to underfloor heating or radiators is just balanced out by heat loss of the building.
That's independent from heat source really. Also if you're using heat pump you need to define efficiency in "how much you pay for power".
If, say you have cheap power at night, it might very well make more financial sense to pump more heat into the system (i.e. heating house a degree or two more) in the night rather than waiting for morning where tariff will make you pay more to do that. Similar if you have solar system.
> If one really needs 25kW heat source, one really needs a 25kW heat source. There is no clever way around it. The real question is whether one really needs 25kW heat source (which can be answered definitively by either measuring the delivered==required power, looking at the peak continuous fuel consumption (let's say the coldest day or week), or by having accurate heat loss model of the building. In a heating season, the buffer cannot realistically be large enough to significantly reduce the power requirement. For example, 1m3 of hot water when used as a buffer can store roughly 30kWh (when heated 25 degC above supply temperature). My house needed 240kWh of energy in the coldest day, so the buffer would only cover 10% of the needed heat.
240kWh is 10kW energy continous. So you wouldn't need 25kW heat pump, you'd need 10kW one working all the time, maybe 12kW if you couldn't tolerate temperature dropping at night by a degree or two. Of course, that's gonna suck if you lower temperature (say going on holiday) then get it back to usual (compared to twice as powerful gas heating) but you can work around that with programming.
The buffer is there mostly to avoid pump from cycling, electric engines like to spin at constant speed instead of being started and stopped every 10 minutes. Also your entire house is a heat buffer too.
Gas boilers are also very often oversized, especially in older homes where someone might've put some isolation in but not tweaked the boiler size for it. Or if you have dual-purpose one that is extra powerful for heating. Less of a problem now as a lot of them can modulate heat output but still.
And actually the condensing gas boilers also like low water temperature on return because the condensation is more efficient.
energy-wise the best solution would probably be gas-engine heat pump (basically heat pump gas engine instead of electric one + piping to also recover heat from that gas motor), but last time I've checked that's pricy for home scale and more maintenance compared to just electric powered one. But you get significantly over 100% efficiency compared to just burning that gas.
Other interesting thing I saw is so-called "co-generators" where you just have electric generator powering your house (and selling excess to the network) + use the waste heat for heating but that looks like a bit hard to balance between too much power and too little heat.
The SpackPack SIM-060 says "Heating Capacity Range: 25,400 – 70,600 Btu/h"
* https://www.spacepak.com/solstice-air-to-water-heat-pumps
Webinar:
Anyways, I don't understand the need to draw these types of "total" comparisons. If you have reliable electricity, a heat pump is probably great, if you don't, then fossil fuels are clearly the way to go.
There is no "one size fits all" energy strategy.
DOE mandates 80% efficiency for new furnaces, and high efficiency units are in the 90-95% range.
That doesn't seem particularly useful.
BTUs from hydrocarbon gases (and hydrocarbons in general) are phenomenal, and Natural gas is generally more of a waste product from oil extraction than anything, so is dirt cheap. The equipment required to use them (a typical furnace or boiler) is also cheap, low maintenance, well understood, and widely deployed everywhere.
Most cold climates use fossil fuel heating.
Heat pumps aren’t terrible, and are vastly more efficient than resistive heat for heating. If the only energy source is cheap and electric, it’s an easy win.
But for areas already widely using fossil fuel heating (such as Germany), switching to heat pumps will increase electrical demand by at least an order of magnitude - best case - and since peak heating demand tends to happen when it’s winter, better have adequate storage too. Germany also has very expensive electricity, so it will dramatically increase costs unless extensive amounts of insulation are also done, increasing capex.
So, if we look at price, and especially if we include capex, it’s only competitive in niche contexts or if we expect fossil fuel costs to be immediately and rapidly increased 4-5x. Even then, if done widely it will break a lot of things unless there is a lot of grid upgrades too. Increasing capex.
It’s why Germany is struggling to switch off. They’re not the only ones.
The were once the leader in nuclear energy. They really should have kept that lead, and built more nuclear plants and aggressively switched to electric first solutions such as heat pumps, EVs etc.
Instead, they are winding down their nuclear power plants, and increasing their reliance on fossil fuels in the near to mid term, at the very least, which means issues like this will plague them for some time.
No idea why they didn't pursue more energy independence when they had the chance
Compared to France (70% from nuclear power, natural gas for heating in only ~1/3 of homes) this hardly looks like leadership.
As for the reasons: There has been a series of events where nuclear reactors weren't properly handled and where politics colluded with the operators to sweep it under the rug. No matter how safe the technology _could_ be, its management was horrendous.
One such example was a "passively safe" reactor that by now is a glowing mess for 40 years already, and will remain so for another 60-80 years before it can be dismantled: https://en.wikipedia.org/wiki/AVR_reactor
Key quote from that Wikipedia article: "The report listed hidden or downplayed events and accidents and described serious concealed problems and wrongdoings. For example, in 1978 operators bypassed reactor shutdown controls to delay an emergency shutdown during an accident for six days."
As long as people argue about the merits of the technology, they miss the German discourse on nuclear power completely.
When the policy was started, the USSR had fallen, the world was on the upswing, etc. etc.
optimism, enthusiasm, etc.
These issues were all called out at the time.
Just... what is your plan with this? The reality is, North European countries are now wholly reliant on there not being a cold winter again. If you check three simple things: the number of MW of heating demands, the lithium prices for a MWh, and the god damn ninety-fifth percentile worst weeks for wind+solar at >45 degrees North, to get the number of hours. You can do this, and ask people with money in the game whilst you're at it. The answer is not ambiguous, and it is no where fucking near regardless of what a Twitter bro with 50 MWh in a desert will prat on about. So why. The Fuck. Haven't you?
This is not saying that technological advancements like SMRs can't change the economics to be more favorable, but it's really not the case if you wanted to start building a plant right now.
So either:
1) we’d need to do massive investment right now (on the order of wartime economic reorganization) for renewables, which no one seems interested in. And while plenty of people seem happy to say things are fine but that don’t even come close to penciling out in reality.
2) maybe actually get better at nuclear.
3) have some non-trivial percentage of the population either freeze to death during some “unexpected” winter storm that was entirely predictable, or go back to fossil fuels (if they can) on an emergency basis.
Or, my guess at the most likely outcome;
4) pretend everything is fine until a bunch of people die, then blame those people for their moral failings. Then start panicking.
1. Overall efficiency: fossil fuel heaters burn fuels directly and produce heat, whereas heat pumps require electricity to be generated somehow and then for the electricity to be used. If you have a heat pump with a COP of 2, but the electricity comes from a natural gas power plant with efficiency of 40%, then that's an "overall" COP of 0.8, not 2. If you have a natural gas heater with 90% efficiency, that's actually more efficient than the heat pump overall, despite having a lower COP.
2. Price efficiency: similar to the above, electricity is more expensive than gas in most markets. Even if the efficiency is double that of a natural furnace, if electricity costs more than double than gas (per unit of energy), you can't really conclude that "heat pumps triumph over fossil fuels".
If you take these factors into account, heat pumps don't really "triumph over" fossil fuels once you get below around freezing. Things get more complicated when you're optimizing for carbon emissions vs energy/cost alone, or the upfront cost of the fossil fuel heater (to have the option of using fossil fuel, you need a fossil fuel heater which costs money, so you forgo that and only use the heat pump you might come out on top if it doesn't get too cold too often), but it's frustrating seeing articles proclaiming "COP > 1 therefore heatpumps better".
In terms of cost, you likely won't save money in many markets, but as long as it does not cost more you are still not behind on that front.
It is also much, much easier to produce electricity at home than extract fossil fuels, and individual energy independence has great value for many people.
1. in some areas you can do worse than natural gas plants, eg. oil/coal power plants
2. Those are all valid points, and I even acknowledge them in my original comment (ie. "Things get more complicated when you're optimizing for carbon emissions vs energy/cost alone"). However my core objection isn't against heat pumps per se, it's that the article uses a simplistic analysis to conclude that heat pumps are better.
>In terms of cost, you likely won't save money in many markets, but as long as it does not cost more you are still not behind on that front.
Source? For last Janurary eia lists residential electricity as 16.11 cents/kwh in the US[1] and $15.28/1000 cf[2]. If you convert that to kwh[3][4], that gets you an effective price of $0.052/kwh for natural gas. Of course prices vary by region and time, but I'm too lazy to do this calculation for every state/region.
[1] https://web.archive.org/web/20230407144604/https://www.eia.g...
[2] https://www.eia.gov/dnav/ng/hist/n3010us3m.htm
[3] https://www.kylesconverter.com/energy,-work,-and-heat/cubic-...
[4] https://www.wolframalpha.com/input?i=1055055852.62+joules+to...
I had a heat pump in an apartment many years ago, and the big down-side to me at the time was that it felt like it was always blowing cold air on me in the winter. I definitely valued the warm feeling I got from natural gas heat! But I suspect that heat pump design has improved a lot in the last 30 years, so I'd be willing to give it another try.
But your point #2 is dead on. The best path to decarbonization is electrification, and expensive electricity is going to slow that down dramatically.