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Most modern EVs have heat pumps. Not using heat pumps to generate heat - exploiting the larger than 100% efficiency you get in the process - offends my sensibil

by audunw 3y ago

Most modern EVs have heat pumps. Not using heat pumps to generate heat - exploiting the larger than 100% efficiency you get in the process - offends my sensibilities. If we have propane, and want to use it for energy/heating, it’d be better to burn it at some large central efficient generator (perhaps supplying waste heat as district heating for nearby homes), and use the electricity to power heat pumps.

bawolff 3y ago
Don't heat pumps stop working around -25C? That is obviously not going to be effective in alberta. (Current temp -36C [not including windchill])
- FredPret 3y ago
  The windchill actually only affects humans - moist skin cools down faster in the wind. But -36 is enough to bring down heat pump efficiency a lot. This site [1] talks about heat pumps that work down to -30. Not good enough to trust your life to if you’re an Albertan. [1] https://www.bchydro.com/news/conservation/2022/cold-weather-heat-pumps.html https://www.bchydro.com/news/conservation/2022/cold-weather-...
  - deleted 3y ago
    [deleted]
  - kevin_nisbet 3y ago
    > Not good enough to trust your life to if you’re an Albertan. I believe the heat pumps intended for these climates provided alternatives for those cold days. If you want to stay all electric, it would include a resistive electric heater, but could be paired with some other fuel source. Personally, I'd seriously consider going ground source where temperatures like this are the norm, but that doesn't work for everyone either.
    - bawolff 3y ago
      That may work for your house, but it really doesn't make sense for the emergency heat source of your vehicle to also need an emergency heat source.
osigurdson 3y ago
At -40C, the COP is only going to be 1.4. A natural gas fired cogen plant is 60% efficient so even without transmission losses this ultra complex arrangement is not more efficient at generating heat. You are conflating the efficiency of generating mechanical energy (where such arguments hold) with generating heat.

by audunw 3y ago

bawolff 3y ago

Don't heat pumps stop working around -25C? That is obviously not going to be effective in alberta. (Current temp -36C [not including windchill])

FredPret 3y ago
The windchill actually only affects humans - moist skin cools down faster in the wind. But -36 is enough to bring down heat pump efficiency a lot. This site [1] talks about heat pumps that work down to -30. Not good enough to trust your life to if you’re an Albertan. [1] https://www.bchydro.com/news/conservation/2022/cold-weather-heat-pumps.html https://www.bchydro.com/news/conservation/2022/cold-weather-...
- deleted 3y ago
  [deleted]
- kevin_nisbet 3y ago
  > Not good enough to trust your life to if you’re an Albertan. I believe the heat pumps intended for these climates provided alternatives for those cold days. If you want to stay all electric, it would include a resistive electric heater, but could be paired with some other fuel source. Personally, I'd seriously consider going ground source where temperatures like this are the norm, but that doesn't work for everyone either.
  - bawolff 3y ago
    That may work for your house, but it really doesn't make sense for the emergency heat source of your vehicle to also need an emergency heat source.

osigurdson 3y ago

At -40C, the COP is only going to be 1.4. A natural gas fired cogen plant is 60% efficient so even without transmission losses this ultra complex arrangement is not more efficient at generating heat. You are conflating the efficiency of generating mechanical energy (where such arguments hold) with generating heat.