Hot water and steam from geothermal systems can be extracted via drilled geothermal wells. Electricity is generated by using the steam, or secondary fluids, to drive turbines, which in turn drive generators. Excess fluids are injected back into the subsurface reservoir to help extend the life of the system.
Hot water from geothermal resources can be used to provide heat directly for an application. Applications can be independent, or connected in series for cost savings. The latter is termed a “cascade system” where each system uses the fluids discharged from the previous process.
Processing industries located close to geothermal resources can use eco-friendly and renewable geothermal energy for heating, which provides economic and productivity benefits.
The Kawerau timber facilities have used geothermal energy for timber drying since the late 1950's. This is the world's largest single user of geothermal steam for process heat using some 5000 TJ/year of geothermal heat energy. Three large direct geothermal heat utilisation activities are associated with the timber industry in Kawerau.