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micro2588today at 4:55 AM0 repliesview on HN

The water at these temperature / depths has a lot of dissolved salts and minerals so it's not (human / ag) usable. Modern designs are closed loop systems where production wells bringing the hot water to the surface go through a heat exchanger to a different working fluid to drive the turbine and then is re-injected back into the reservoir. There is consumptive water use for fracking the reservoirs in these types of enhanced geothermal systems, but beyond that it's more water redistribution in the area around the well systems where re-injection and production lead to different pressurization from pumping / natural ground water replenishment rates.