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by measurablefunc
234 days ago
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That obviously doesn't make sense if you know basic physics. Converting gas into heat by combusting it heats up the air in the room directly. Burning that gas in a turbine & then transferring that energy through a bunch of transformers to get to the heat pump can't give you more heat than what went into combusting the gas in the first place. This obviously doesn't work in reverse to cool a room but the direction I laid out is obviously correct.
You're not using funny units, you're confused about the thermodynamics of the situation. Heat pumps are more efficient air coolers than standard air conditioners but they're not giving you more energy than what you put into it. |
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I assure you I am not, it is actually you who still seem confused about where the energy is coming from.
> they're not giving you more energy than what you put into it.
When you burn gas in a furnace, all of the energy that raises the temperature of the house comes from the gas.
When you run a heat pump you have two sources of energy:
1. Electricity running the thing.
2. Heat from the outside that you're moving inside.
#2 is where most of the energy that actually heats up the house comes from. The electricity is used to move it from outside the house to inside.
> Burning that gas in a turbine & then transferring that energy through a bunch of transformers to get to the heat pump can't give you more heat than what went into combusting the gas in the first place.
It actually can. A combined cycle plant can be ~60% efficient (chemical energy -> electricity). Say another 70% for getting it from the plant to your heat pump, then a COP 3 (or "efficiency" of 300%) gives you 0.6x0.7x3 or 1.26. So for every J of natural gas you burn in that plant, you'll heat your house with 1.26 J (compared to at best 1 J, realistically 0.9 J, for a gas furnace).
If you instead look at a ground source heat pump, you can get a COP of ~7 [0]. You're now putting ~3 J of heat into your house of each J of natural gas.
[0]: https://en.wikipedia.org/wiki/Heat_pump#Performance