Geothermal energy, derived from the Earth's internal heat, is a reliable, sustainable, and environmentally friendly energy source. This blog delves into the science of geothermal energy, different types of systems, benefits, challenges, and the future of this exciting technology. (Photo: Geothermal energy produces about 20% of New Zealand’s electricity.)
What is Geothermal Energy?
• Geothermal energy is the thermal energy stored beneath the Earth's surface.
• This heat is a remnant of the planet's formation and is continuously replenished by radioactive decay in the Earth's core.
• It manifests as hot springs, geysers, volcanoes, and underground reservoirs of hot water and steam.
This illustration depicts a cross-section of the Earth, clearly showcasing its internal layers: the crust, mantle, outer core, and inner core. Arrows of varying thicknesses, radiating outwards from the inner core, emphasize the intense heat present within the Earth's center. The arrows might be color-graded, with warmer colors like red and orange closest to the core, transitioning to cooler yellows on the outer layers.
How We Convert Geothermal Energy into Usable Power
There are three main types of geothermal power plants:
• Dry Steam Plants: The oldest and simplest type. They directly use steam from underground reservoirs to spin turbines and generate electricity.
• Flash Steam Plants: The most common type. They pump hot water from deep reservoirs under high pressure. As pressure decreases, water turns to steam, powering turbines.
• Binary Cycle Plants: These plants operate at lower temperatures. Hot water is passed by a secondary fluid with a lower boiling point, which turns to vapor to drive the turbines.
Beyond Electricity: Geothermal Energy for Heating and Cooling
• Geothermal Heat Pumps (GHPs): GHPs use the stable temperature just below the Earth's surface to heat and cool buildings, saving energy.
• Direct Use: Hot water from geothermal sources can be used directly for heating buildings, greenhouses, aquaculture, and industrial processes.
Benefits of Geothermal Energy
• Renewable: Geothermal energy is virtually inexhaustible and constantly replenished.
• Reliable: It generates electricity 24/7 regardless of weather, making it a great baseload power source.
• Environmentally Friendly: Geothermal plants have negligible greenhouse gas emissions and a small land footprint.
• Scalable: Geothermal technologies exist for both large-scale power plants and small-scale residential use.
Challenges and Considerations
• Location Specific: High-temperature resources suitable for electricity generation are often found in geologically active areas.
• Upfront Costs: Drilling and installing geothermal systems can be initially expensive.
• Induced Seismicity: Some geothermal projects have been linked to minor earthquakes.
Statistics: Geothermal Energy's Growth
• Global geothermal power capacity reached almost 16 GW in 2022 [Global Geothermal - Market and TechnologyAssessment]
• The United States is the world's largest producer of geothermal electricity. [Geothermal Report June 8 2021]
• Geothermal heat pumps are becoming increasingly popular for their energy efficiency. [New Analysis Highlights Geothermal Heat Pumps as Key Opportunity in Switch to Clean Energy]
The Future of Geothermal Energy
• Advanced technologies like Enhanced Geothermal Systems (EGS) could unlock vast geothermal potential in less geologically active regions.
Resources
• US Department of Energy - Geothermal Technologies Office: https://www.energy.gov/eere/geothermal/geothermal-basics
• International Renewable Energy Agency - Geothermal Energy: https://www.irena.org/Energy-Transition/Technology/Geothermal-energy
• National Geographic – Geothermal Energy: https://education.nationalgeographic.org/resource/geothermal-energy/
Here's a list of countries with significant geothermal power generation and links to relevant websites. Note that not all countries have a dedicated geothermal energy website:
United States:
US Department of Energy - Geothermal Technologies Office: https://www.energy.gov/eere/geothermal/geothermal-basics
Indonesia:
Indonesian Ministry of Energy and Mineral Resources (Geothermal info may be under broader energy pages): https://www.esdm.go.id/en
Philippines:
Department of Energy - Renewable Energy Management Bureau: https://www.doe.gov.ph/renewable-energy/geothermal
Turkey:
253490-national-renewable-energy-action-for-turkey.pdf (enerji.gov.tr) : [Turkey - A geothermal success story: A retrospective and prospective assessment - ScienceDirect]
New Zealand:
GNS Science (Geothermal research institute): Geothermal Energy - GNS Science | Te Pῡ Ao
Mexico:
Secretaría de Energía (SENER) [Website in Spanish]: https://www.gob.mx/sener/energia-renovable/geotermia
Italy:
Enel Green Power (Major geothermal energy company): https://www.enel.com/en/our-companies/enel-green-power/geothermal
Kenya:
Kenya Electricity Generating Company (KenGen): https://www.kengen.co.ke/
Iceland:
Landsvirkjun (National power company): https://www.landsvirkjun.com/
Japan:
Ministry of Economy, Trade and Industry (METI) - May have geothermal info under general energy: https://www.meti.go.jp/english/
Costa Rica:
Instituto Costarricense de Electricidad (ICE): https://www.ice.go.cr/
El Salvador:
LaGeo (Geothermal energy company): [LaGeo - Energía Geotérmica en El Salvador, centrales]
Important Notes
Some websites may have information in languages other than English.
Smaller geothermal projects may not have dedicated websites.