Of all the ways to produce renewable power, no technology manages to do it as consistently and reliably as geothermal. In fact, according to data collected by the Energy Information Administration (EIA), only nuclear power has a higher average capacity factor:
Capacity factor compares the power produced with the maximum generating capacity. The long-term average is around 90% for nuclear, 70% for geothermal and 50-70% for coal-fired and natural gas-fired power sources.
Wind and solar power technologies are much more variable and have much lower capacity factors that can and do drop to zero when the wind doesn’t blow or the sun doesn’t shine. This means that these energy sources generally have to be backed up by other sources of firm power (power that is available on demand). Unlike most other renewable options, geothermal is considered a firm power source.
