Quote from: K-Dog on Jul 30, 2023, 10:11 PMOld faithful erupts about once an hour and squirts out about 20,000 gallons of boiling water each time.  There are 3600 seconds in an hour.  That is an average flow rate of about twenty liters a second.

But since the eruptions only last three to five minutes I could easily claim 250 liters a second.

The technique being used here doesn't require erupting geisers of the Old Faithful kind, which are relatively rare. It just requires an underground heat source, present anywhere the earth's crust is relatively thin or where there are cracks which allow the magma from the earth's mantle to come up near enough to the surface to be within drilling range for the kind of horizontal drilling done to extract shale oil.  Range there is down to about 10,000 ft.  Hawaii around Mt Kilaueha is a good example, as is just about all of Iceland.  These type of volcanoes don't usually erupt explosively like My. St. Helens, most of the time they just push out magma to the surface where it cools and hardens.  Right under the surface though there are large pools of molten lava.

The trick here is to drill down to just above a large pool of molten rock and run pipe through which you pump cool water and the magma just below the pipe acts like a burner to heat this water to just below boiling temp at 190F.  This comes back up the pipe to the surface where it runs through a heat exchanger and boils a refrigerant that runs a turbine.

The only limitations on flow rate are how big and how many pipes you run and how much water you can run through before you start cooling down the magma pool.  Bigger the pool and faster it is getting heated up from magma lower down, the more water you can pump through it before you start cooling it too much.

According to the article, their pilot well pumps 63L/sec and they plan a larger one for their next project.  The only question here is how many places have a magma pool large enough and close enough to the surface to drill down to and run the pipe.  They don't even really need much water for it either, since it is a closed loop system.

RE