Geothermal utilization is a mature and proven technology. It provides base-load power to the grid with capacity factors as high as 98%. Production is unaffected by changes in season or weather with no fuel costs. Storage or backup-power is not required.
Although geothermal energy can be produced in two different ways: in the form of electricity and the form of heat, electricity production is probably the most prominent form of geothermal energy utilization in the renewable energy debate of today. People tend to forget this technology is a mature technology having already been in use in a small power generation installation in Lardarello, Italy in 1904.
Electricity generation is the most important form of utilization of high/intermediate-temperature geothermal resources (>150°C). Geothermal power plants fall into two general categories. Choosing the most suitable generation method is dependent on temperature, flow rates and pressure. The fluid is derived from the resource by drilling 1.000-4.000 m deep wells. The water from those wells is either used directly in a steam turbine (flash plant) or to heat up a secondary working fluid, which has a lower boiling point temperature (binary plant). The low-temperature resources are widely used for direct heat use.
Over 72 countries utilize geothermal energy for direct use, accounting for over 16,000 MWth of installations. Space heating is its most common direct application.
