ELI5- why isn’t geothermal power universally feasible?

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We can drill down and pump out oil and natural gas from anywhere in the world, even building refineries on massive rigs in the middle of the ocean.

We can dig down and extract coal through endless tunnels that stretch out under the sea.

Why is it not feasible to just drill down far enough to pump water down and allow steam to rise up and power turbines? I know some parts of the world have the required heat closer, but surely tapping into the heat that perpetually sits under our feet is a huge contribution to the solution of replacing fossil fuels?

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Anonymous 0 Comments

If you drill the average place, you can get heating for a house at 30-300m. 30 is economical, 300 is not.

If you drill to 3000m you can get something around 50-100 C degrees. That’s not enough to run a electric power plant. You can use a stirling engine but: you drilled 3000m to get 5 horsepower per 1000kg of engine, that’s not even gonna cover the water pumping of the well., let alone spinning a generator for electricity.

In specific places you can drill a 100m hole and get 200-1000 C degrees. That’s reasonably ok for getting steam and spin a turbine that then spins a generator. But rock is a good insulator. As soon as you run the system the drill hole cools down to 100-500 C. So you can get some power, but not a lot of power. It’s ok in Iceland, there’s few people, little power demand, and geothermal costs less than importing electricity. Geothermal powerplant does have an excess of heat as every powerplant, so in Iceland you get free heating for houses too. But let’s say you are in the middle of france, summer, you find an epically good spot, you make your plant and all you get is excess heat that is useless and 1 Megawatt of electricity… in a place where a nuclear plant makes 1000 megawatts… is it worth it?

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