Heat Pumps: Mythology and Actuality | Hacker News Reader

Heat Pumps: Mythology and Actuality

thegwpf.org

Looks like oil industry astroturfing [1] to me. The group that published this (GWPF) is basically an anthropogenic climate change denying lobby group that refuses to reveal its funding sources [2].

Yeah, color me skeptical about their publication that is essentially saying gas systems are better than electric heat pumps for the environment.

- [1](https://www.youtube.com/watch?v=FOi05zDO4yw)

- [2](https://en.wikipedia.org/wiki/The_Global_Warming_Policy_Foun...)

All these comparisons depend on so much context. Price of gas, price of electricity, possibility for home generation, climate, access to gas lines, building design, and so on.

Literally every country, or every region, will have different constraints and parameters. What's best for me, may or may not be good for you.

For me the bottom line is this; I can generate my own electricity, I can't drill for my own gas.

I'm not an absolutist, I still use gas for cooking (for stove, oven is electric), and for some heating, but since I can generate electricity [1], I tend to want to use that first.

[1] solar, and yes I have the roof, and sun available. Residential wind can be tricky, if you're really lucky a small stream is nearby and personal hydro is fantastic.

I think the lede is missing. Arguing they are uneconomic with Solar and PV reducing electricity costs against gas is counterfactual. So, assuming its both counterfactual and true, what alternative is proposed, which is not "keep gas"

If the alternative is direct electric heating, electric hot water storage systems and electrically heated radiators and sub-floor heating say so.

(unless I have completely misread the article it demolishes some myths about heat pumps but winds up saying their LCOE may be good compared to gas but capital cost kills them economically)

Yeah perhaps I’ve been misinformed but this kept saying that countries with more renewables had less efficient grids and electricity costs were higher.

Am I misreading it? I thought the exact opposite was true and nowadays renewables are generally cheaper.

It's such a contradictory article. It's conclusions are divorced from most of its substantive points.

Solar should have lower transmission cost overall because of local solar. I am unsure where "less efficient grids" comes from unless it's because of terawatts in a single giant coal burner or nuke. Non UK economies like mine have no nuclear and do have expensive transmission nets but it's a socialised cost and a net benefit overall.

He somehow elides over a 2 to 3x advantage in one space but worse overall. How worse? Why?

His strawman myth demolition was good.

I don't know enough about heat pumps to comment about the substance of this report, but looking at the list of their other reports at the end,it seems worth pointing out the heavily ideological, global warming denying biases of the group that wrote this.

This https://www.theguardian.com/environment/2022/may/04/climate-...

https://www.theguardian.com/environment/2022/oct/27/strip-cl...

front

https://www.theguardian.com/environment/2022/may/23/fossil-f...

for

https://www.theguardian.com/environment/2022/nov/21/charity-...

oil and gas

https://www.theguardian.com/environment/2023/feb/08/calls-fo...

lobbyists.

The Guardian is a channel for eco-lobbyists so that kind of makes things even. Read what is written by both and draw your own conclusions. For me the conclusion is that air-tp-air heat pumps can work when power is cheap and plentiful but they fail when they are most needed here in the Swedish winter. Mind you, they still price best but the COP (conversion factor) end up around or below 1. Water-to-air and water-to-water heat pumps fare better and have higher COPs but they are a lot more expensive to install due to the higher equipment costs and the costs of drilling a well or digging in a heat exchanger. The combination of a heat pump with an extra heat source, preferably a wood-burning stove or boiler makes for warm winters independent of electricity prices.

We're heating our farm using only wood since we have plenty of it but have an air-to-air heat pump in a new office in the new barn as an experiment.

Air-Air should be more popular in the UK - modern units have very attractive COP (gain) - nearly 5.0 - without complexities of right-sizing pipework and emitters.

I think it's a tragedy that they aren't more popular. One of the reasons is that they don't qualify for installation grants. This in turn means the installers (ahem, grant-harvesters) are bad-mouthing them vs air-water to potential customers.

From what I gather those high COPs are not actually met in real life since they occur when the temperature difference between intake and outlet are too low to be useful. In practice the SPF (Seasonal Performance Factor, the average COP for a heat pump used for heating and hot water through all seasons) for air-source heat pumps in Germany lies around 3 (value given is 2.99), water-source heat pumps end up around 3.7 (value given is 3.72) [1] which makes them preferable over resistance heating but not necessarily economically effective given the discrepancy between electricity and gas prices and higher installation costs. These results are from 2009, it is likely that more recent heat pumps can achieve better conversion factors.

[1] https://wiki.ucl.ac.uk/download/attachments/11962823/staffel...

I'm talking about the emitter rather than the source. (ductless) Air/Air is relatively unused in the UK (except for aircon) for the (stupid) reasons described, work perfectly well even in very cold climates) and offer extremely good COP values (4.68@ 8C, 2.46@ -8C) which is likely better than retro-fit of Air/Water, given the difficulty of right-sizing such a scheme in an existing, older building. If the government really wants uptake of heat pumps, they should be pushing for these to be installed in flats (like they do in most of the rest of the world).

As you say (and the original article points out) - whether it's economically a good idea depends a lot on the electric:gas price ratio, which currently is around 3.2, so the COP needs to exceed 2.95 or so for the OPEX to be lower (let alone the CAPEX of having the thing installed in the first place). And historically the gap has been even larger - nearly 5:1, meaning the gain would have to be 4.56 even to break even - "somewhat ambitious"!

> In the UK, the electricity:gas price ratio has been increasing for many years, as increasing penetration of renewable energy makes the grid progressively less efficient.

Does anyone know any more context on this? I found this surprising. I would have assumed renewables would be cheaper than fossil fuels. This feels like fossil fuel industry misinformation, but I don't have the facts here.

Regardless, I agree that in some places a heat pump is just not economical. I have a natural gas furnace, and gas usage is pretty cheap in California, at least when compared to electricity.

My original plan was to get solar panels installed, and then switch to a heat pump once the furnace needs replacing. Ditto for my now-gas water heater. Then the electricity powering the heat pump would be "free". An added bonus is that I would get air conditioning along with it, which I currently do not have, and that would essentially be "free" pulling from the solar panels as well. (Sadly, the solar panel install didn't work out, but that's another story.)

I wasn't planning on switching to a heat pump because of cost (though with solar panels, it would presumably end up being cheaper than burning gas), but because I think burning fuel in a closet in my house isn't a great idea health-wise, and burning fuel in general isn't great for the planet. Although I'd find it really hard to give up my gas stove...

It's bullshit.

The ratio is increasing because of how the energy market works. Renewables are cheaper than fossil fuels. But fossil fuels set the price.

Well that's gross. Do you have any links to explainers on this; I just did some searching but nothing useful came up. Probably I just don't know the magic keywords to use...

https://www.euronews.com/my-europe/2022/08/09/watch-heres-ho...

hth

https://robinlinacre.medium.com/hey-andrew-great-insights-he...

Heat pumps work well if you have net metering, less so if you don't but assuming that you're trying to reduce your overall bills insulation comes first, then you can heat with far less power and that in turn may get you within range of being able to use solar+heatpump for heating and supplement with gas for when that isn't enough. This should drastically cut your heating bill.

"Supplement with gas" implies dual fuel heating. Supplement either with less loss or more use of direct electric heating at higher cost surely?

What gets lost here is the goal of removing gas entirely. If you stop at reduction, sure your logic makes sense. But it implies a gas economy at scale with fugitive emissions, reticulation (bottled or piped) production and pollution consequences.

I'd love to be able to remove the gas completely. But the reality is that in the winter the sun doesn't shine enough and the price of electricity is such that gas still wins out economically. So I'm happy to convert any surplus electricity to heat but after that the gas burner comes on, as much as I hate it.

No disagree either with your logic or decisions, it leverages the best outcome for you over sunk costs and existing infrastructure (basically the same) but at scale, it's going to have to change unless something else mitigates the total system costs of gas. You cannot force the change alone. A willingness to assume communal cost is probably required in classic "privatise the profits socialise the costs" outcome.

Yes, absolutely. But in the case of this house that would require a teardown and rebuild, and that would be even more wasteful. My goal is essentially to shift the time the gas heater has to come on to mid November and the time when it can be switched off completely again to early March. That leaves several months where it will run - intermittently - versus how it used to be: from September through late April. The house was badly insulated and had a very inefficient heater. Triple glazing, foam in the wall gap and lots of measuring and tweaking later as well as a new heater so we should be doing much better than before. Our monthly pre-pay went from something astronomical to zero and averages out to about 300 / month before the latest batch of improvements. I'm curious to see how we'll manage this winter.

Incidentally, that's why I over-installed on solar: I didn't care all that much about the overproduction in summer, that just gives a tiny bit of money. But it will help to substantially offset the amount of gas consumed in the winter. Even so I have no illusion about being able to do entirely without gas, but compared to how it was it is already much better (est. -70%).

Here's an analysis I did a few years back when evaluating whether to install an air-to-air pump: https://observablehq.com/@robinl/retrofitting-air-source-hea...

I installed it at a cost of around £1,500, and it's been great. It probably is a relatively expensive method of carbon abatement, however.

At the time, I was comparing against an electric car, and I concluded it was a significantly cheaper way of reducing my carbon impact (we only drive around 10k miles a year)

For reference, it reduced my gas usage from around 10k KWh to 5k KWh, resulting in a reduction in emissions of around 500kg a year

Not much to say about geothermal heat pumps. And the whole discussion about electric vs gas cost is a perfect example of why we need plentiful and cheap nuclear energy. Electricity should be so cheap that everybody wants a heat pump because of the economic benefit.

I follow Rosenow on twitter. he tried to tell me that Heat Pumps /were/ economic, because the gas/electric ratio would change /in the future/ ! "I'll wait until then, then".

I've been saying the things in this report for years. Nobody I know is particularly attached to gas as a method of heating their home, they simply want to do it at the lowest cost possible. Make heat pumps have an ROI of less than 10 years and it'll change overnight.

The UK government keeps banging the drum of heat pumps, then navel-gazing when the public won't install them. This is not because - outside of a few anti-green nutbars - they don't think they work, it's because they can see no economic case for them to do so. Making comparisons to countries with different unit prices doesn't help. Instead of the wildly complex subsidy scheme (Which merely funds a grant-harvesting installation industry, at the expense of viable systems like air-air), simply moving green tariffs to sit exclusively on gas would make a big difference.

One comparison this report misses is against variable electric tariffs (eg Octopus Agile which has 1/2 hr pricing). I suspect the gap would narrow, but I don't know by how much, and doing that you're taking a bet about the average electric unit cost in the future vs gas. My guess here - and it's the same reason I currently don't think a battery system is investable - is that the difference between 'cheap' periods and 'expensive' periods is going to narrow as time-of-use tariffs encourage the significant extra demand from EVs away from peak-load times.

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