Geothermal concentrates the thermal flux to the geothermal energy site.
What happens in practice is that such sites end up being rate-limited by either the thermal flux of the surrounding rock, in the case of dry holes which are bored and take out heat directly, or by depleting the groundwater and/or hydrothermal reservoir which feeds a "wet" geothermal project (as with California's Geysers).
Dry holes end up having a limited effective life of a few decades, based on what I've seen, after which there's insufficient thermal energy to drive electrical generation (though it may be suitable for other lower-grade heating applications). Wet holes vary in response depending on how rapidly groundwater is replenished. I believe that the Geyers has dried up numerous wells. In places with ample water infiltration (e.g., near coastlines or in wet climates), I speculate that intrusion of fresh cold water might cool the geothermal reservoir somewhat.
But the source heat, which is radiating from the Earth's core though the mantle and crust, has an effectively fixed flux. There's only so much heat radiating outwards, and a few localised pinpricks and steam generators won't effect that measurably. Volcanoes are far larger and similarly have little overall effect.
What happens in practice is that such sites end up being rate-limited by either the thermal flux of the surrounding rock, in the case of dry holes which are bored and take out heat directly, or by depleting the groundwater and/or hydrothermal reservoir which feeds a "wet" geothermal project (as with California's Geysers).
Dry holes end up having a limited effective life of a few decades, based on what I've seen, after which there's insufficient thermal energy to drive electrical generation (though it may be suitable for other lower-grade heating applications). Wet holes vary in response depending on how rapidly groundwater is replenished. I believe that the Geyers has dried up numerous wells. In places with ample water infiltration (e.g., near coastlines or in wet climates), I speculate that intrusion of fresh cold water might cool the geothermal reservoir somewhat.
But the source heat, which is radiating from the Earth's core though the mantle and crust, has an effectively fixed flux. There's only so much heat radiating outwards, and a few localised pinpricks and steam generators won't effect that measurably. Volcanoes are far larger and similarly have little overall effect.