6 ms·
> Gas is so efficient for heating Nope. Put one kWh of gas in, get maybe 0.9kWh of heat out. Put one kWh of electricity into a heat pump and get at the very l
by brtkdotse 5y ago
> Gas is so efficient for heating
Nope. Put one kWh of gas in, get maybe 0.9kWh of heat out.
Put one kWh of electricity into a heat pump and get at the very least 3 kWh of heat out.
- lotsofpulp 5y ago> Put one kWh of electricity into a heat pump and get at the very least 3 kWh of heat out. Even when it is below freezing outside?
- brtkdotse 5y agoIt’s -10C here right now and my heat pump is pulling less than 3kW to heat the whole house.
- teaearlgraycold 5y agoIt’s a matter of the refrigerant you use. Don’t worry about the freezing point of water.
- dpark 5y agoHeat pump efficiency drops as the difference between the indoor and outdoor temperature grows. No one specifically cares about the freezing point of water for this, but it’s a good proxy for “big temperature difference”.
- insaneirish 5y ago> Even when it is below freezing outside? Yes. For instance, one of the heat pumps in my house has a coefficient of performance of 3.2 at 17F/-8C. Reference: https://ashp.neep.org/#!/product/51106 https://ashp.neep.org/#!/product/51106
- tzs 5y agoHeat pumps such as Mitsubishi's "Hyper-Heat" models should be above 3 to 1 down to a little below freezing, and better than 2 to 1 down to around 0℉ (-18℃). They are down to about 1 to 1 at -15℉ (-26℃).
- hashimotonomora 5y agoElectricity is of (much) higher exergy than natural gas so it’s not a directly comparable measure.
- SECProto 5y agoEven burning natural gas in a peaker plant to generate electricity (nTh ≈ 0.6), and account for transmission losses(~0.9), and then using that electricity to run a heat pump (~2.5) - is still more efficient than natgas space heating
- ubercow13 5y agoWhy is electricity still ~5x as expensive as gas then? (in the U.K. at least)
- erichocean 5y agoBecause generation is the cheapest part of the electrical grid. Distribution and "overhead" cause end-user electricity prices to jump 3-5x.
- SECProto 5y agoA small fraction of the cost of electricity is fuel cost. A much larger fraction is staffing, maintenance, and capital costs amortization. Distribution and maintenance fees are largely covered by per kWh price. The turbine I mentioned to do that generation costs $xx,xxx,xxx and is generally only cost effective to run as a peaker so that cost has to be amortized over fewer hours per day. Unlike natural gas hot water heaters etc, the turbines can't be built by the tens of thousands using cheap manufacturing techniques.
- nine_k 5y agoBurning gas for heating is less efficient than burning gas to produce electricity and use it to run a heat pump. Burning gas for cooking is more efficient than burning it to generate electricity and turn it back to heat in an induction stove. I can imagine banning natural gas from apartments to avoid catastrophic explosions, but it's not about daily efficiency.
- dpark 5y ago> Burning gas for cooking is more efficient than burning it to generate electricity and turn it back to heat in an induction stove. Is it? Induction cooktop heating is quite efficient. Gas is extremely inefficient. Huge amounts of heat roll up the side of the pot/pan and into the air, to be blown outside by the hood vent. There’s quite a bit of loss in generating and transmitting electricity but I am not sure it’s worse than gas cooktop efficiency.
- nine_k 5y agoThe stove may be 100% efficient. Thermal electricity genetation is at best 60% efficient, and transmission losses add a couple percent. Do you suppose that gas stove wastes a lot of heat when heating a pot that stands on it?
- crooked-v 5y agoMy gas stove heats the pot, but also the cabinets above and around the stove and the entire small kitchen. Just being able to feel the air temperature go up by a couple of degrees would certainly suggest it's throwing off more waste heat than what's actually going into the pan.
- dpark 5y agoA gas stove is very close to 100% efficient at converting gas to heat. It is certainly not 100% efficient at putting that heat into the pot. Gas produces heat by combusting with oxygen and essentially generating hot air. The air will impart some of its heat to the pot. A ton of the heat will end up just heating the air around the stove (or being dumped outside if you’re running a hood vent). This article claims 40% efficiency and provides a citation, for what it’s worth. https://www.greenbuildingadvisor.com/article/efficient-cooking https://www.greenbuildingadvisor.com/article/efficient-cooki... It’s worth noting that natural gas transmission can’t be 100% efficient either. I don’t know what the loss is but it certainly takes energy to push natural gas through pipelines and there is loss in the system due to leaks.