Hybrid heat pump water heaters are a great application of recapturing waste heat. Put one next to your HVAC and use excess heat to heat your water. Some utility companies offer rebates for...
Hybrid heat pump water heaters are a great application of recapturing waste heat.
Put one next to your HVAC and use excess heat to heat your water. Some utility companies offer rebates for installing them.
Heat pumps are amazing. Indeed the best application of waste heat is to … be reused instead of turned back into electricity (which, for the most part, will most likely be turned back into heat...
Heat pumps are amazing. Indeed the best application of waste heat is to … be reused instead of turned back into electricity (which, for the most part, will most likely be turned back into heat anyway).
I can't wait to see the efficiency of the houses and apartments of 50-100 years from now. I do think that with climate change becoming a more seriously-considered issue in new buildings, there will be a lot more thought and $$$ put into efficient and passive systems for cooling and heating. Or maybe that's just my optimism talking…
Waiting for the day that homes have hot- and cold water piping loops for all your thermal control needs. Your computer heats up a room too much? Hook it into the cold water loop. At the end of...
Waiting for the day that homes have hot- and cold water piping loops for all your thermal control needs. Your computer heats up a room too much? Hook it into the cold water loop. At the end of that sits a heat pump that cools it back down and heats up the hot water loop. Need a room heated? Hot water loop. Fridge? Cold water loop. Dishwasher? Heat exchanger + hot water loop. In the garden, a big tank is buried that buffers the difference between heating and cooling demands, big enough to keep you warm in the winter.
That last part does actually exist. But I don't think it's been done in such a way as to hook devices into the loop.
Linus is doing a home reno that has a hot water home heating system in it I love the this general idea. Would definitely require substantial insulation for both loops. Have tap water come in, use...
I love the this general idea. Would definitely require substantial insulation for both loops. Have tap water come in, use that for generic cooling, feed that into a holding tank to divert to a boiler for heating.
Energy is energy. It's lost every time it's converted, so the fewer conversions done the better. Even among AC/DC conversions. I'd be curious to know how much electricity is lost on the numerous...
Energy is energy. It's lost every time it's converted, so the fewer conversions done the better. Even among AC/DC conversions.
I'd be curious to know how much electricity is lost on the numerous AC/DC conversions. I think we're hitting a time it may be worth running DC in our buildings, given that the vast majority of our devices use it now. Outside the Kitchen and Basement, I can't think of another room that relies on AC.
Is DC as easy to step down? Because in order to eliminate the power brick in a desktop computer, for example, you'd need 500W at 12V or so, which comes out at 40 amps. 40 amp wiring is ridiculous,...
Is DC as easy to step down? Because in order to eliminate the power brick in a desktop computer, for example, you'd need 500W at 12V or so, which comes out at 40 amps. 40 amp wiring is ridiculous, and that's just for one device. So obviously, running at the voltage we need is infeasible, so stepping down has to happen close to the point of use. And I think to remember stepping down/up of DC is hard. So we have decentral conversion anyway.
For lighting circuits, absolutely. Lighting a home with LEDs shouldn't take much more than a few hundred watts, and I'm not sure of the voltages that would be doable, but that strikes me as a lot more doable, considering the cabling we currently use for lighting is just as long and rated for just as many amps.
On the point of "energy is energy", I'm not sure I understand you point. Do you mean that converting waste heat into useful heat is a useless conversion?
Not exactly. Since Conservation of Energy is a thing, and the conversions are not perfectly efficient, the best thing to do with waste heat is to convert it to use it for heat (ala a water heater...
On the point of "energy is energy", I'm not sure I understand you point. Do you mean that converting waste heat into useful heat is a useless conversion?
Not exactly. Since Conservation of Energy is a thing, and the conversions are not perfectly efficient, the best thing to do with waste heat is to convert it to use it for heat (ala a water heater by a furnace), rather than back to electricity and heat again.
Also, low temperature heat sources inherently will have lower theoretical thermal efficiency (see: Carnot law), even before you take these efficiencies into account
Energy is energy. It's lost every time it's converted, so the fewer conversions done the better. Even among AC/DC conversions.
Also, low temperature heat sources inherently will have lower theoretical thermal efficiency (see: Carnot law), even before you take these efficiencies into account
Link to actual paper: https://www.nature.com/articles/s41563-021-01064-6 Of particular note, the measurment of ZT which is a measurment of how efficiently the thermoelectric device. Table 2 in...
Of particular note, the measurment of ZT which is a measurment of how efficiently the thermoelectric device. Table 2 in this paper gives a listing of Peak ZT based on material and temperature ranges, with examples in the list falling between ZT 0.5 and ZT 1.4. According to the OP paper, the newer material composition of tin and selenium has a ZT of 2.6 to 2.8.
I'm not entirely clear on how to translate the ZT rating into something I can understand (like 20% or 80% efficient), but the difference does seem quite significant.
Hybrid heat pump water heaters are a great application of recapturing waste heat.
Put one next to your HVAC and use excess heat to heat your water. Some utility companies offer rebates for installing them.
Heat pumps are amazing. Indeed the best application of waste heat is to … be reused instead of turned back into electricity (which, for the most part, will most likely be turned back into heat anyway).
I can't wait to see the efficiency of the houses and apartments of 50-100 years from now. I do think that with climate change becoming a more seriously-considered issue in new buildings, there will be a lot more thought and $$$ put into efficient and passive systems for cooling and heating. Or maybe that's just my optimism talking…
Waiting for the day that homes have hot- and cold water piping loops for all your thermal control needs. Your computer heats up a room too much? Hook it into the cold water loop. At the end of that sits a heat pump that cools it back down and heats up the hot water loop. Need a room heated? Hot water loop. Fridge? Cold water loop. Dishwasher? Heat exchanger + hot water loop. In the garden, a big tank is buried that buffers the difference between heating and cooling demands, big enough to keep you warm in the winter.
That last part does actually exist. But I don't think it's been done in such a way as to hook devices into the loop.
Linus is doing a home reno that has a hot water home heating system in it
I love the this general idea. Would definitely require substantial insulation for both loops. Have tap water come in, use that for generic cooling, feed that into a holding tank to divert to a boiler for heating.
That looks neat. Not taken to the extreme as I outlined, but then again that's unlikely to be possible as a retrofit.
Energy is energy. It's lost every time it's converted, so the fewer conversions done the better. Even among AC/DC conversions.
I'd be curious to know how much electricity is lost on the numerous AC/DC conversions. I think we're hitting a time it may be worth running DC in our buildings, given that the vast majority of our devices use it now. Outside the Kitchen and Basement, I can't think of another room that relies on AC.
Is DC as easy to step down? Because in order to eliminate the power brick in a desktop computer, for example, you'd need 500W at 12V or so, which comes out at 40 amps. 40 amp wiring is ridiculous, and that's just for one device. So obviously, running at the voltage we need is infeasible, so stepping down has to happen close to the point of use. And I think to remember stepping down/up of DC is hard. So we have decentral conversion anyway.
For lighting circuits, absolutely. Lighting a home with LEDs shouldn't take much more than a few hundred watts, and I'm not sure of the voltages that would be doable, but that strikes me as a lot more doable, considering the cabling we currently use for lighting is just as long and rated for just as many amps.
On the point of "energy is energy", I'm not sure I understand you point. Do you mean that converting waste heat into useful heat is a useless conversion?
Not exactly. Since Conservation of Energy is a thing, and the conversions are not perfectly efficient, the best thing to do with waste heat is to convert it to use it for heat (ala a water heater by a furnace), rather than back to electricity and heat again.
Also, low temperature heat sources inherently will have lower theoretical thermal efficiency (see: Carnot law), even before you take these efficiencies into account
Link to actual paper: https://www.nature.com/articles/s41563-021-01064-6
Of particular note, the measurment of ZT which is a measurment of how efficiently the thermoelectric device. Table 2 in this paper gives a listing of Peak ZT based on material and temperature ranges, with examples in the list falling between ZT 0.5 and ZT 1.4. According to the OP paper, the newer material composition of tin and selenium has a ZT of 2.6 to 2.8.
I'm not entirely clear on how to translate the ZT rating into something I can understand (like 20% or 80% efficient), but the difference does seem quite significant.