How are we going to heat our cities in the future?

Changed the title picture again. Air happened to be in such a configuration that the smoke from the hood district heating plant travelled horizontally. It uses fuel oil and isn’t in use most days. Only when it’s quite cold like today (about -10 C).

Making coal electricity and using the waste heat for district heating apartment buildings is quite effective and has a pretty low workload compared to separate houses and oil heaters or what you have.

There isn’t any really good “green” solution for this. Making district heat with wood has its problems for example, and having heat pumps everywhere is inefficient and even inelegant in many senses. First making electricity with a low efficiency and then using that to make heat again with a low multiplier. You need magnets and bearings and whatnot in both devices. Are there even enough rare earths?

Building nuclear plants close to cities isn’t nice either. If you built them far away, you’d need to build really long pipes and that gets inefficient again. It also hurts the nuke’s electricity output surprisingly much. You could probably optimize the plant for better district heat production though, and the Russians have done that in some cold cities. But you can’t have a single nuclear plant as the only thing that’s heating a city: it would be devastating if an unplanned break left a million people cold in their homes.

In the future though, buildings can be much more energy efficient, so that’s the biggest saver. That too can be overdone, and I don’t like many modern buildings which have tiny awkwardly placed windows. A human produces about 70 watts of heat, and electronic equipment produces some waste heat too. “Zero energy” houses can take the heat from the exiting air and use it to heat the incoming air (like penguins do with the blood in their feet), making large savings (and at the same time making it hard to retrofit some old buildings.)

Dividing Finland’s yearly energy consumption with all the seconds in the year and all the people, we get nine kilowatts of constant power, day and night, summer and winter, for each person. That’s huge.

One big part of that is heating. It’s also a big missing part of the discussion.

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