Using heatpump to generate electricity?

HansRoos

HansRoos

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Is it possible to use a heatpump to generate electricity? Thus far I haven't really found effective, thermal efficient methods of converting hot water to electricity. Sure one can theoretically use the heat to turn a steam turbine, but those are only 36% thermal efficient. What other ways can one do it potentially to harvest the 300% energy yield from a Heat Pump water heater?
 
Ugh, thermodynamics hurts my brain. But you'd probably have to factor in thermal losses, as well as how long it takes to heat the water, versus the power output and for how long.

I suspect the reverse wouldn't be very efficient, otherwise it would be commonplace already...
 
I think domestically it won't be possible, but maybe industrially? I thought that maybe you could accumulate the heat in a type of boiler, increase the pressure, and use some kind of bladder or piston to hydraulically lift a very heavy object into the air. The object (like a metal weight) will then go up and when it's up, can come down slowly, while connected to a permanent magnet motor or generator and generate electricity. That way you can also eliminate the use of battery storage.
The way I thought of eliminating heat losses would be to also use solar panels to make up for some losses. But still I can't see that this will be efficient more than say 50% or 40% and then you still need to power the heatpump with 30% of that.
 
Mike Hoxbig said:
Ugh, thermodynamics hurts my brain. But you'd probably have to factor in thermal losses, as well as how long it takes to heat the water, versus the power output and for how long.

I suspect the reverse wouldn't be very efficient, otherwise it would be commonplace already...
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Only other way I could think of is to use the expanded gas and send it up as well, through a pipe, let it condense into a tank or accumulator and then fall down as a liquid to power a hydro powerstation. But that would also have significant lossses
 
A stirling engine is essentially a reversed heat pump.

The efficiency of a heat pump depends on the difference in temperature, so making steam is not going to be very efficient.
 
Stirling engine is very inefficient (I think). But what if the steam or "gas" doesn't then come from water but from something with a lower boiling point? Maybe still use the refrigerant instead of water to drive some type of hydraulic cylinder, since hydraulics are quite efficient (I think).
 
HansRoos said:
What other ways can one do it potentially to harvest the 300% energy yield from a Heat Pump water heater?
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Why not just use the hot water as, er, hot water? It's a valuable commodity in itself, and if you don't think so, your wife will.
 
RonSwanson said:
Why not just use the hot water as, er, hot water? It's a valuable commodity in itself, and if you don't think so, your wife will.
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Wife with hot water won't help much when pumping water from a remote source, and cables spanned over the 10km distance keeps getting stolen thus losing pumping time:rolleyes:
 
Efficiency based on a quick Google is 10%, so not worth it, look at sliding scale of heat trying to achieve vs environment temperature, getting it to a point where you can get energy out of it requires too much input.
 
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