Geothermal Energy Production

Geothermal energy is heat derived from within the earth’s sub-surface. Water and/or steam carry the geothermal energy up to the earth’s surface. Depending on its characteristics, geothermal energy can be used for heating and/or cooling purposes or it can be harnessed to generate clean electricity. This key renewable energy resource meets a significant share of the electricity demand in countries like Kenya, Iceland, El Salvador and New Zealand.

The electricity is transmitted to homes and industries through low-high voltage lines
Some steam escapes from the cooling towers into the atmosphere
When the water reaches the surface, the pressure is dropped which causes the water to turn to steam
Steam spins a turbine which is connected to a generator that produces electricity
Steam cools off in a cooling tower and condenses back to water
Cooling Tower
Cooling Tower
Cooled water is pumped back into the earth to begin the process again
Hot water is pumped from deep underground through a well under pressure
Hot reservoir rocks

Geothermal Direct Use Beyond Electricity

Direct use of geothermal energy dates back over thousands of years. In modern direct-use systems, a well – drilled into a geothermal reservoir – provides access to a steady stream of hot water. In the well, the hot water is brought up to the surface using a mechanical system consisting of piping and heat exchangers and controls. The heat from the water can then be used directly for its intended purpose.

A disposal system then injects the cooled water underground through a re-injection well allowing for a cyclical conventional-heating process. Geothermal direct uses also include snow-melting, swimming pool heating, milk pasteurisation and food drying.

Heating greenhouses to raise plants/flowers
Fish pond heating
House heating (district heating)
Cold water flows underground and interacts with hot reservoir rocks
The convectionally-heated water flows up the well in this cyclic process
Hot reservoir rocks
Fractured rock formation
Hot water flows up the well and is piped to various applications
Re-injection well that dispenses cooled water from various direct-use applications underground
A well is drilled into a geothermal reservoir to provide a steady stream of hot water
A disposal system injects cooled water from the greenhouse underground through a re-injection well
Hot water delivers heat to a greenhouse through a piping system to optimize plant growth
A disposal system injects cold water from the fish pond into a pipe system
Hot water piping heats a fish pond to optimize fish reproduction
A disposal system injects the cold water into a pipe system
Hot water delivers heat to a house through a piping system

Geothermal Production in Select Countries

United States • 3,653 MW
Mexico • 951 MW
Iceland • 755 MW
Italy • 944 MW
Turkey • 1,347 MW
Kenya • 850 MW
Indonesia • 1,948 MW
Philippines • 1,868 MW
Japan • 549 MW
New Zealand • 1,005 MW

Source: ThinkGeoEnergy [2019]