摘要:Electricity from geothermal resources has the potential to supply a significant portion
of US baseload electricity. We estimate the water requirements of geothermal
electricity and the impact of potential scaling up of such electricity on water
demand in various western states with rich geothermal resources but stressed water
resources. Freshwater, degraded water, and geothermal fluid requirements are
estimated explicitly. In general, geothermal electricity has higher water intensity (l kWh − 1) than thermoelectric or solar thermal electricity. Water intensity decreases with increase in
resource enthalpy, and freshwater gets substituted by degraded water at higher resource
temperatures. Electricity from enhanced geothermal systems (EGS) could displace 8–100%
of thermoelectricity generated in most western states. Such displacement would increase
stress on water resources if re-circulating evaporative cooling, the dominant cooling system
in the thermoelectric sector, is adopted. Adoption of dry cooling, which accounts for 78% of
geothermal capacity today, will limit changes in state-wide freshwater abstraction, but
increase degraded water requirements. We suggest a research and development focus to
develop advanced energy conversion and cooling technologies that reduce water
use without imposing energy and consequent financial penalties. Policies should
incentivize the development of higher enthalpy resources, and support identification of
non-traditional degraded water sources and optimized siting of geothermal plants.