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Comment by nisegami | Hacker News Reader

Though not directly related, this does remind me of an idea I once had.

I live in the Caribbean. My house effectively has a few heat pumps running most of the time (split air conditioning units) as well as a dryer and a water heater. Why can't the heat moved by those units be used to heat water or to dry clothes? By using the heat directly, there wouldn't be a need to use a Peltier unit or deal with the associated losses.

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A combination of interface (how do you get the water heater to use the excess heat?), quality (a/c waste heat isn't that hot), and matching generation with demand.

There are power plants that use excess heat for heating. The term is cogeneration or combined heat and power.

In the Caribbean you get unlimited free energy from the sun, considering that solar panels are very cheap you could just rig the system to dump all excess power to the water heater, but considering you already get unlimited solar power you could just place the water tank in the sun to heat water. If that is not enough a home made aluminum can heat pipe plus water pump or just a long black hose with a water pump would nearly boil your water during the day.

Using solar panels to generate electricity is nominally illegal here actually. I know other Caribbean islands use solar water heating pretty extensively, but it's never been a thing here. I suspect it's a matter of lack of Government and business incentives as we've always been a fossil fuel based economy with relatively affordable electricity.

Rheem manufactures a heat pump HW heater that could use the exhaust of the AC heat pumps and dry with a fan in the AC. Maybe a set up like that?

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