Can someone here explain why heatpumps are the new hotness? (Sorry.) Despite the hype, all I can discern is that they are just air conditioners that can pump in the other direction ("reverse cycle"), and the thermodynamics is poorly explained in the popular literature. Why are they suddenly the thing that can save the world? What am I missing?
My degree is in physics. I can handle the truth.
Thank you.
@robpike As several people have said, the great thing about heat pumps is that the theoretical maximum efficiency is greater than 1. The theoretical maximum is T₁/Δ𝑇 (which looks a lot like the expression for a Carnot engine and is derived similarly). You get pretty large numbers if you plug in real-world temperatures, especially for places like California.
Which is all 19th century thermodynamics. So why are people talking more about heat pumps than they did a decade ago? I think it basically comes down to two things.
- Mini split heat pumps have gotten cheaper and better. Commercial products don't achieve the theoretical maximum, of course, but if you look at the manufacturers' spec sheets for the coefficient of performance, the numbers are surprisingly good.
- Photovoltaic panels have gotten cheaper and better, so heating using carbon-neutral electricity is more practical than it was when solar power was expensive.
