The actual efficiency of a geothermal power plant using a 200 C geothermal resource is only about 7%. Take this value as typical of California's Geysers geothermal field, which produces 900 MW of electric power.
a) Find the actual rate of geothermal heat extraction at Geysers
b) it's estimated that 35EJ of energy could be extracted from the Geysers before the temperature dropped from 250 C to 150 C minimum for a vapor-dominated geothermal plant. Given your answer in (a) how long will the Geysers geothermal resource last before the temperature reaches 150 C
I am not sure what equation to use
The Attempt at a Solution
Starting at part A I know I have to find the rate of geothermal heat extraction but do not know the formula to do so.
Does this have something to do with change in temperature? It's the only thing I can think to do but am not sure if this is right