Power Plants

I wonder how much of the spike in demand and electricity shortage down south is due the common air-source heat pumps having to kick on their electric pre-heaters due to extreme cold conditions (at least for the south). In the south with warmer temperatures being the norm, they rely on heat pumps to pump heat out of buildings in the winter (air conditioning), and pump heat into buildings during the winter. Many large buildings, especially down south, use air conditioners with reversing valves, that allows them to pump heat into buildings, by compressing the heat in outdoors air.

Such systems work well, and are very energy efficient in moderate temperatures. You can typically compress enough heat out of 35 or 40 degree air to keep a building a comfortable 70 or 75 degrees. But the problem is when the air temperature drops below 35 degrees — there is simply not enough heat in air for compressor to work. Such air-source heat pumps then contain electrical resistance pre-heaters, similar to electric space heaters that a lot of people have. The pre-heaters are activated to heat the air when it’s cold to compress it out of outdoors air. While resistance heaters release all of the heat in electricity, power plants are lossy and 55-70% of all heat in fuel is discarded and not turned into energy. So when they fire up the electric heat, it’s quite lossy.