4 ms·

> For example, a heatpump can produce 5MW of heating from 1MW of electricity by concentrating the heat from the environment. Don't those struggle in cold clima

> For example, a heatpump can produce 5MW of heating from 1MW of electricity by concentrating the heat from the environment. Don't those struggle in cold climates (e.g. winters consistently below freezing)? > An electric car is 90% efficient while a combustion vehicle is about 30% efficient On the other hand, even the best batteries have far less energy density than a gallon of gasoline, and some of that "waste" heat can be put to good use (e.g. heating in cold climates).

timbit42 4y ago
Yes, the colder the air is, the less efficient a heat pump is. My 10 year old heat pump has a COP of 3 but shuts off at -15C because below that it's less efficient than an electric baseboard heater. Newer air-to-air heat pumps have a COP of 4 or higher so they can handle down to -20C or -25C. I keep my EBBs set to come on a few degrees below where I keep the house so they will kick in when the heat pump shuts off and they kick out when the heat pump comes back on. This tends to happen at night when I don't mind the house getting a bit cooler anyway. Where I live in Canada, the heat pump typically only shuts off half a dozen nights in the second half of January. It's not like my heat pump is useless 6 or 8 months of the year. There are also geothermal heat pumps that push/pull heat to/from water from underground (eg. a well, a pond, or a buried coil of pipe) where, even in the winter, the ground remains warm. These don't suffer a loss in efficiency in the winter. Regarding EVs, most EVs get between 3 and 4 miles/kWh. The Porsche Taycan gets only 2 miles/kWh. The Tesla Model 3 gets 5 miles/kWh. The Aptera gets 10 miles/kWh, which with the 100 kWh battery, gives you 1,000 miles of range. Fully Charged Show - Aptera (time-indexed to efficiency discussion): https://youtu.be/mpiH-Y-HOvE?t=135 https://youtu.be/mpiH-Y-HOvE?t=135

timbit42 4y ago

Yes, the colder the air is, the less efficient a heat pump is. My 10 year old heat pump has a COP of 3 but shuts off at -15C because below that it's less efficient than an electric baseboard heater. Newer air-to-air heat pumps have a COP of 4 or higher so they can handle down to -20C or -25C. I keep my EBBs set to come on a few degrees below where I keep the house so they will kick in when the heat pump shuts off and they kick out when the heat pump comes back on. This tends to happen at night when I don't mind the house getting a bit cooler anyway. Where I live in Canada, the heat pump typically only shuts off half a dozen nights in the second half of January. It's not like my heat pump is useless 6 or 8 months of the year. There are also geothermal heat pumps that push/pull heat to/from water from underground (eg. a well, a pond, or a buried coil of pipe) where, even in the winter, the ground remains warm. These don't suffer a loss in efficiency in the winter. Regarding EVs, most EVs get between 3 and 4 miles/kWh. The Porsche Taycan gets only 2 miles/kWh. The Tesla Model 3 gets 5 miles/kWh. The Aptera gets 10 miles/kWh, which with the 100 kWh battery, gives you 1,000 miles of range. Fully Charged Show - Aptera (time-indexed to efficiency discussion): https://youtu.be/mpiH-Y-HOvE?t=135 https://youtu.be/mpiH-Y-HOvE?t=135