TL;DR
using/generating energy always emits heat as waste and there is an upper limit of efficiency that we are not that far from. if that energy was generated via something that is not a natural heat gradient for the earth’s surface there is a net increase of heat in the earth system simply by generating and using energy.
a lot of energy sources fall into this: fossil fuel, nuclear, geothermal, etc. two that don’t are (certain types of) solar and wind, since their energy would eventually be dissipated onto earth’s surface whether we intercept or not.
that waste heat is currently estimated to be ~2% of the heating power caused by global warming, so already significant. we essentially have an upper limit on sustainable energy usage on earth (and therefore an avg per person usage) or we will have Global Warming 2: Waste Heat Boogaloo.
Waste heat is only about 1/100,000 of the warming we get from burning fossil fuels. It won’t really become significant unless we use a nuclear-heavy approach to decarbonization.
thanks for the article. it seems that number only accounts for the heat released during energy generation at the power plant but there is also significant heat waste when it’s consumed. AC units, electric heaters, refrigerators, lightbulbs, pumps, basically all other machines. an individual unit might not produce that much but there are billions of them.
That doesn’t really change the picture much. A typical coal-burning power plant turns about 1/3 of the energy in the coal into electricity. Highly-efficient combined cycle gas turbines might turn 60% of the energy in the gas into electricity. That energy is the amount of waste heat that those devices produce.
turbines are still energy generation, heat is also emitted when that produced electricity is consumed.
- about 15% of electricity the world produces is used for refrigeration
- about 20% of electricity the world produces is used for computers
all machines have efficiency < 1 and therefore emit heat when used. many of those machines even have the goal of producing/moving heat.
