In a geothermal system—not the kind in Iceland, which confusingly has the same name—pipes are buried underground where they stay at a constant temperature. Refrigerant circulates in the pipes, warming air and water in the winter and cooling it in the summer.
This is the greatest thing in the world: essentially free energy. Oh, you still need pumps to keep the refrigerant circulating, but that's not much. And of course it's entirely carbon free.
It's also expensive, though not wildly so. So why isn't it more popular? Why don't states like California require it for all new residential housing? Am I missing something about its greatness?
I replaced a gas-fired forced hot air furnace and air conditioner six weeks ago. I live in southwestern Ohio.
I really wanted to go with a heat pump, to be ready for an all-green-electric future. But I just could not get the numbers to work out. With current gas and electricity prices, running the heat pump would cost me 2x in operational expenses, along with extra capital costs (but surprisingly, not that much). Even a hybrid system (that can use both gas and the heat pump for heating) wasn't that much more.
Ground-source heat pump? 4x the cost. $40,000 vs $10,000. Plus maintenance concerns.