3 ms·
Heat pumps move heat from one place to another. They pump the heat. That is how they achieve 300% returns, they move 300% of the heat energy that they consume t
by andrewxdiamond 4y ago
Heat pumps move heat from one place to another. They pump the heat. That is how they achieve 300% returns, they move 300% of the heat energy that they consume to operate.
But that heat isn’t free. It has to be produced somewhere. You must “consume” the heat to produce electricity.
If you tried to generate power in the way you postulated, you would ignore the 300% number and instead look at the conversion rate between the energy it takes to produce that heat and the energy output.
- XorNot 4y agoIf you're pulling heat from the air though, you're just absorbing solar power efficiently. And this wouldn't be a bad way to do it if you could make it work: at any given time, there's always sun shining somewhere on Earth, just not where we need it. A heat pump which could extract enough of a differential to power itself using a turbine, isn't impossible. The real issue is such a thing at scale would functionally be a storm generator: you'd be pulling warmer air in the upper troposphere down to ground level, chilling it, and then releasing it.
- chrismorgan 4y agoTo frame this another way since I missed part of the point on first read: the heat pump has the same maximum theoretical efficiency (Carnot efficiency) as the heat-to-electricity generator does (just in the opposite direction), and cannot exceed it. If you model the two parts independently, then in the ideal scenario, your 300% efficient component is balanced by something that physically cannot exceed 33⅓% × some-other-variable efficiency. You therefore model the system as just a heat-to-electricity generator that consumes the atmospheric heat directly at some-other-variable efficiency. (I believe this to be accurate, but I am speaking far beyond my expertise and invite correction if I have erred.)