Comment by gruez | Hacker News Reader

Comment by gruez | Hacker News Reader

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While I feel like heat pumps have come a long way and have their uses, the article/study grossly misrepresents the advantage that heatpumps have over fossil fuel heaters.

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".

It is not energy free to extract, store, and transport natural gas, and often it is more wasteful than producing electricity (hydro, solar, wind, etc). Plus, presuming that electricity is coming from fossil fuels when they are only a percentage of generation, and virtually the entire world is working to reduce that use every single day as the second part of the process of switching to sustainable energy, is a limited perspective.

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.

> It is not energy free to extract, store, and transport natural gas, and often it is more wasteful than producing electricity (hydro, solar, wind, etc). Plus, presuming that electricity is coming from fossil fuels when they are only a percentage of generation, and virtually the entire world is working to reduce that use every single day as the second part of the process of switching to sustainable energy, is a limited perspective.

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 did not want to make the same point as others, but it has already been pointed out that 3-4 COP for heat pumps is the more common range for comparison than 2 COP. I have done the math in my area, which is very expensive for electricity, and it still pencils out without factoring in my reduced costs if I get solar (which yes, does finally pay for itself).

I didn't downvote this, but I will criticize this analysis: it's good to look at factors beyond COP (although 2 is the lower end of the COP that I would expect from a heat pump, not the average that I would expect), but this fails to go all the way and look at the ultimate problem: warming potential. And the warming potential of burning natgas in a home is still way higher than using a heat pump powered by a natgas plant, because methane is an extremely potent greenhouse gas and because our natgas infrastructure is notoriously leaky.

By "Warming potential" I guess you mean "contributes more towards global warming," not "I feel warmer with natgas heat"?

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.

NatGas power plants typically have an efficiency above 55% and most heat pumps operate well above a COP of 2 unless it is super cold.

But your point #2 is dead on. The best path to decarbonization is electrification, and expensive electricity is going to slow that down dramatically.

Electricity seems to generally be expensive where the “free market” has enabled private companies to extract wealth, and then reasonable/cheap and reliable where a Goverment entity provides it. I love my 9c cad Goverment power (and that is after the last right leaning government saddled it with 20 billion in additional costs going straight to private companies)

Using heat pumps for hot water also necessitates storage cylinders, vs modern gas boilers which heat on demand and don't need a cylinder. You can argue about the relative efficiency of this vs heating water on demand (depends a lot on how predictable your usage patterns are) but the space requirements, which may imply a need to remodel in an unsatisfactory way even if someone has the square feet to spare, are a real barrier.

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