I wrote the story. The efficiency here isn't breaking the first law of thermodynamics. It's just the industry's way of measuring how much work gets done for a certain amount of input. If the work is heating or cooling, then shifting heat from in one direction or another can be done using heat pumps, which move three units of thermal energy for every unit of electrical energy consumed. Might that explain the conundrum?

But then aren't you comparing apples and oranges when you call both that and the loss as heat and noise from coal as "efficiency"?

Well, we're not interested in a thermodynamic comparison. We're interested in a useful-energy-obtained for useful-energy-spent comparison. For instance, if I leave a block in the sun and then bring it inside, I have only expended the energy to move the block out and then move the block in. It doesn't make sense for me to include the sun's contribution to the system because that's not a cost I incur.

The actual apples to apples comparison in efficiency _is_ the heat emitted by the block in my house divided by the cost of moving the block.

This is a property of _what the device is doing_ (moving heat from one place to another) as opposed to being a property of how it's powered, though.

Heat pumps move more heat (which has the same unit as energy, that's why you can put the numbers in a ratio and get a unitless number) than they use energy for the process. This is the crucial point for heating with them, otherwise they would make little sense (except for using them for cooling) over having an electric heater instead.

Here is something to read on this:

https://en.wikipedia.org/wiki/Coefficient_of_performance

Jump to "Examples" if you like concrete examples.

Air conditioners move heat from inside the house to outside. So, they can provide more cooling (move more heat) than the equivalent input energy. That is how you come up with greater than 100% efficiency.

Another example is to light up a candle, then use a peltier element and a heatsink to generate electricity. Then use that electricity to power a led. The outcome is that you have some of the candle light, but you will have a much more light from the led.

This discussion of heat pumps makes me want to add that we may also ignore cogeneration too much. We just don't think about heat flows and temperature enough.

There is, of course, the communal thing, done in Sweden and Russia and college campuses, with a power plant and steam pipes going to apartments.

But what about an appliance for suburban America? Like, combine a gas turbine generator with an HVAC system and hot water tank (pretty sure you can buy things like this in Germany). No unsolved technical problems here. You generate electricity for your home, heat it with waste heat, and absorb temporary excesses in capacity by usefully heating water. You could imagine integrating other things too: If you need more heat than you use electricity, then you might as well use the electricity to do something high-value (cryptocurrency is a crime against the environment, but you might as well compute some hashes in your resistive heater). All this becomes an elaborate way to burn natural gas to make heat, but you get a bunch of other things out besides. The "smart controller" aspect then becomes interesting -- but even that is "just simple automation", not super-difficult AI.

Maybe logistically, the "everything is electric; electricity comes from renewables/nuclear; and heat comes from heat pumps" solution is easier in the long run?

But this more "decentralized heat engines" solution has the "advantage"(?) that it could run on biomass, which is easy to store (however, I am aware of the problems of wood pellets and deforestation).

What is wrong with the concept of a heat pump? A resistor converts electricity into heat 100% efficiently, and a heat pump is often 3x as efficient at heating a house vs electric baseboards.

> a heat pump is often 3x as efficient at heating a house vs electric baseboards.

Not if you consider the whole "indoor + outdoor" referential, in that case you will always get below 100% efficiency.

True, but no one cares if they make the outside air 0.05ºC hotter in the summertime or 0.1ºC colder in the wintertime.

On an individual level for sure, multiply this by a state / country population, and you get non-negligible impact.

Draw a boundary around a city and any lasting temperature change is solely an energy balance question.

Any heat that you move into the house in the winter leaks out within the day (asymptotically), so this doesn’t become a localized runaway effect.

> What is wrong with the concept of a heat pump?

Something overlooked is that heat pump will leak refrigerant. It's not really not a matter of "if" but "when", physical systems fail.

Refrigerants are pretty nasty greenhouse gases.

Ok then the electric baseboard is 30% efficient vs the heatpump which is 100% efficient.

No; you're missing the point - 100% of the energy in an electric baseboard system is converted into heat. It's 100% efficient. There is no more effective way to turn electricity into heat than resistively.

A heat pump doesn't turn electricity into heat. It moves heat from one place (outside) to another place (inside); and can seem more efficient because the system isn't closed.

Ah makes sense. Thanks for taking the time to explain

But a resistor converts 100% of the electrical energy it consumes into heat. So if you were to take the same amount of electrical energy and run a heat pump, you could get 3x more heat into a room. In that sense, the heatpump is 300% efficient.

Yeah one can argue semantics all one wants but you still get 3 to 4 times more low grade heat per kwh from a heat pump than a resistive heater. And that's what you actually care about.

How are you calculating efficiency? It's usually:

efficiency = useful work / energy input

Efficiency is not calculated relative to the best performing machine.

That was easy. Just put a few of them back-to-back and you'll have 10X as much energy.

Because this doesn't violate the second law of thermodynamics it is impossible to get to 10X - https://en.wikipedia.org/wiki/Coefficient_of_performance