12 ms·

While that's true you do need to take into account the limited efficiency of power plants as well, especially when it comes to heating. Simply burning gas to g

While that's true you do need to take into account the limited efficiency of power plants as well, especially when it comes to heating. Simply burning gas to generate heat is basically 100% efficient, if you convert it to electricity first you'd need a COP of at least 1.7 to recover the energy lost while generating the electricity.

bryanlarsen 3y ago
A good heat pump has a COP of 4.
- dahfizz 3y ago
  In ideal conditions. Even good heat pumps with COP >=4 will drop below 2 when it's cold out
  - throwaway473825 3y ago
    If it's very cold, yes. But the average should still be well above 3: > Similarly, in Finland, tests of air-to-air heat pump systems from various manufacturers resulted in COPs of 3 at -10C and 2 at -20C. Source: https://www.carbonbrief.org/guest-post-how-the-energy-crisis-is-boosting-heat-pumps-in-europe/ https://www.carbonbrief.org/guest-post-how-the-energy-crisis...
  - bryanlarsen 3y ago
    Judging by how much insulation the typical English house has, it doesn't get cold there.
    - stoobs 3y ago
      Not as cold as the Nordics, sure, but depending on cycles, it can drop a few degrees below freezing between November - March The main issue is that homes were designed to trap and keep heat in, rather than true insulation, which means that as summers get warmer, our homes turn into ovens, with no way to cool them down properly. Case in point last summer with UK temps hitting 40C and above for a few weeks. Government are trying to kill off the old gas boilers though, with heat pumps being pushed very heavily, not sure if they're enforcing it yet or not though. Apparently they're also looking at switching out natural gas for a hydrogen mix, but that means having to rework a lot of the piping/valves as hydrogen needs much higher standards than currently applied.
      - HPsquared 3y ago
        With the high summer temperatures (likely to rise further with climate change), I wonder why more people aren't fitting forced air heating/cooling. That would kill two birds with one stone. Even just a simple mini-split system.
        vidarh 3y ago
        The British seems to like to suffer in the heat. Every summer colleagues laugh at me for having AC units, and every summer they start loudly complaining about how hot it is a week or two later.
      - _oyks 3y ago
        Yeah, had to get clued up on this for new house in London. A few points: 1. It is unlikely that hydrogen will be pushed heavily by the UK gov because of the expensive pipe rework. The reason they're pushing hard for heat pumps is because of the Glasgow Climate Pact; they're on the hook to reduce carbon emissions or pay heavy fines. To that extent, subsidising heat pumps becomes financially less unviable for them than doing nothing. 2. Regarding the heat in summer; the houses insulate well but don't do much to prevent heat coming in from the windows during summer. There are some pretty useful half-fixes; mvhrs+insulation, or recessed windows/overhangs/sunshades massively aid this. For those who rent that's not much help though :(
    - vidarh 3y ago
      Being from Norway but living in the UK: The average UK house is not built for UK temperatures... Insulation here is a bad joke, at least in older housing.
  - throwaway22032 3y ago
    In the most populated regions of the UK it doesn't realistically go below -5c basically ever. The average minimum temperature in the winter months in London is 3c above freezing.
    - EwanToo 3y ago
      London had a -8C night earlier this year https://www.mylondon.news/weather/london-weather-coldest-night-12-26046599 https://www.mylondon.news/weather/london-weather-coldest-nig...
      - sgt101 3y ago
        as noted in the article - a once in 12 ish year event. So, 1/4000...
        nindalf 3y ago
        Yeah we'll be fine unless extreme weather events become more common.
        lnsru 3y ago
        But then it’s nasty blackout. Somebody still needs to design electricity grid for one of these very rare events.
        Gwypaas 3y ago
        Burn some fossil fuels from a "national emergency reserve". Perfect is the enemy of good.
        vidarh 3y ago
        A whole lot of other electricity demands drop massively at night, so while it needs to be planned for, the coldest nighttime period is also the time the electricity grid currently sees the lowest demand.
        3y ago
  - speedgoose 3y ago
    I live in a relatively cold place and my heat pump extract heat from the ground. It's worth it where it's cold.
    - fatfingerd 3y ago
      I did a double take on that claim about outdoor temperatures as I've always assumed people were talking about ground source heat pumps.
- contravariant 3y ago
  In practice or is that what the manufacturers claim? Either way you should take into account you lose about 40% of that by simply converting the fuel to electricity, which is kind of the opposite of what happens when moving from combustion engines to electromechanical engines.
  - Certhas 3y ago
    Depends on operating regime, but newly installed pumps typically are used in a way that gets close to 3. You can generate electricity with a gas power plant at 50%, use that to operate heat pumps, and you will warm your house more than directly burning the gas. Or put another way, in a gas dominated grid, switching from gas heating to heat pumps saves carbon gas emissions.
  - chii 3y ago
    > you lose about 40% of that by simply converting the fuel to electricity while that is true, it is only a stepping stone towards generating electricity renewably (let's say wind or solar). The consumer ultimately decides the method (via market forces), and they are the easiest to convert first. If the demand for gas heating drops because of electrification, gas demand would fall (but the cost of extraction remains the same/similar), and therefore, makes electricity cheaper and cheaper. The losses from current electricity conversion from gas at the plant is merely a short term loss for a better long term 'future', and i would consider it a cost of electrification.
mechagodzilla 3y ago
With the most common high-temperature hydronic heating, it's closer to 80% efficiency when running steady-state, and lower than that as the duty cycle decreases (if the system is oversized or for the 99% of the time you're not at the design temp). The remaining energy escapes as hot, uncondensed flue gases. Modulating/condensing boilers can get up to like 95% if you're running with ~100-120F water temperatures, but at that point you can also readily run with an air-to-water heat pump.

bryanlarsen 3y ago

A good heat pump has a COP of 4.

dahfizz 3y ago
In ideal conditions. Even good heat pumps with COP >=4 will drop below 2 when it's cold out
- throwaway473825 3y ago
  If it's very cold, yes. But the average should still be well above 3: > Similarly, in Finland, tests of air-to-air heat pump systems from various manufacturers resulted in COPs of 3 at -10C and 2 at -20C. Source: https://www.carbonbrief.org/guest-post-how-the-energy-crisis-is-boosting-heat-pumps-in-europe/ https://www.carbonbrief.org/guest-post-how-the-energy-crisis...
- bryanlarsen 3y ago
  Judging by how much insulation the typical English house has, it doesn't get cold there.
  - stoobs 3y ago
    Not as cold as the Nordics, sure, but depending on cycles, it can drop a few degrees below freezing between November - March The main issue is that homes were designed to trap and keep heat in, rather than true insulation, which means that as summers get warmer, our homes turn into ovens, with no way to cool them down properly. Case in point last summer with UK temps hitting 40C and above for a few weeks. Government are trying to kill off the old gas boilers though, with heat pumps being pushed very heavily, not sure if they're enforcing it yet or not though. Apparently they're also looking at switching out natural gas for a hydrogen mix, but that means having to rework a lot of the piping/valves as hydrogen needs much higher standards than currently applied.
    - HPsquared 3y ago
      With the high summer temperatures (likely to rise further with climate change), I wonder why more people aren't fitting forced air heating/cooling. That would kill two birds with one stone. Even just a simple mini-split system.
      - vidarh 3y ago
        The British seems to like to suffer in the heat. Every summer colleagues laugh at me for having AC units, and every summer they start loudly complaining about how hot it is a week or two later.
    - _oyks 3y ago
      Yeah, had to get clued up on this for new house in London. A few points: 1. It is unlikely that hydrogen will be pushed heavily by the UK gov because of the expensive pipe rework. The reason they're pushing hard for heat pumps is because of the Glasgow Climate Pact; they're on the hook to reduce carbon emissions or pay heavy fines. To that extent, subsidising heat pumps becomes financially less unviable for them than doing nothing. 2. Regarding the heat in summer; the houses insulate well but don't do much to prevent heat coming in from the windows during summer. There are some pretty useful half-fixes; mvhrs+insulation, or recessed windows/overhangs/sunshades massively aid this. For those who rent that's not much help though :(
  - vidarh 3y ago
    Being from Norway but living in the UK: The average UK house is not built for UK temperatures... Insulation here is a bad joke, at least in older housing.
- throwaway22032 3y ago
  In the most populated regions of the UK it doesn't realistically go below -5c basically ever. The average minimum temperature in the winter months in London is 3c above freezing.
  - EwanToo 3y ago
    London had a -8C night earlier this year https://www.mylondon.news/weather/london-weather-coldest-night-12-26046599 https://www.mylondon.news/weather/london-weather-coldest-nig...
    - sgt101 3y ago
      as noted in the article - a once in 12 ish year event. So, 1/4000...
      - nindalf 3y ago
        Yeah we'll be fine unless extreme weather events become more common.
      - lnsru 3y ago
        But then it’s nasty blackout. Somebody still needs to design electricity grid for one of these very rare events.
        Gwypaas 3y ago
        Burn some fossil fuels from a "national emergency reserve". Perfect is the enemy of good.
        vidarh 3y ago
        A whole lot of other electricity demands drop massively at night, so while it needs to be planned for, the coldest nighttime period is also the time the electricity grid currently sees the lowest demand.
        3y ago
- speedgoose 3y ago
  I live in a relatively cold place and my heat pump extract heat from the ground. It's worth it where it's cold.
  - fatfingerd 3y ago
    I did a double take on that claim about outdoor temperatures as I've always assumed people were talking about ground source heat pumps.
contravariant 3y ago
In practice or is that what the manufacturers claim? Either way you should take into account you lose about 40% of that by simply converting the fuel to electricity, which is kind of the opposite of what happens when moving from combustion engines to electromechanical engines.
- Certhas 3y ago
  Depends on operating regime, but newly installed pumps typically are used in a way that gets close to 3. You can generate electricity with a gas power plant at 50%, use that to operate heat pumps, and you will warm your house more than directly burning the gas. Or put another way, in a gas dominated grid, switching from gas heating to heat pumps saves carbon gas emissions.
- chii 3y ago
  > you lose about 40% of that by simply converting the fuel to electricity while that is true, it is only a stepping stone towards generating electricity renewably (let's say wind or solar). The consumer ultimately decides the method (via market forces), and they are the easiest to convert first. If the demand for gas heating drops because of electrification, gas demand would fall (but the cost of extraction remains the same/similar), and therefore, makes electricity cheaper and cheaper. The losses from current electricity conversion from gas at the plant is merely a short term loss for a better long term 'future', and i would consider it a cost of electrification.

mechagodzilla 3y ago

With the most common high-temperature hydronic heating, it's closer to 80% efficiency when running steady-state, and lower than that as the duty cycle decreases (if the system is oversized or for the 99% of the time you're not at the design temp). The remaining energy escapes as hot, uncondensed flue gases. Modulating/condensing boilers can get up to like 95% if you're running with ~100-120F water temperatures, but at that point you can also readily run with an air-to-water heat pump.