eli5: If we’re all sitting above the magma and heat in Earth’s mantle, what are the barriers to tapping that heat in each municipality to provide local affordable electricity?
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The crust of the earth. The geomthermal barrier averages to 20-30 Kelvin/km after a kilometer of so. Right ok… our Turbines for electricity production are around 200-400 Celcius.
So you’d need to drill 1-2 holes to at least 10-15 kilometers deep depending on do you flow material through or pump in and then out to expand. Now that is a lot of mass flow and lot of pressure to keep it liquid underground since steam has little density and therefor little mass can go through.
So to get watet to like 570F and have it remain liquid, you need to have it at around 30Mpa that is 300 bar or 4351Psi.
On top of this you need enough mass flow to make a turbine run.
It would take more effort and energy to achieve this than we can extract. The loop would also have to be perfect or else it stalls because there is no pump that can pull it from 15km. When drilling you inject water to get the oil move up.
However if you are volcanically active area, you don’t need to go deep to get lots of energy. Just look at Iceland.
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