Sign up to access the complete lesson and track your progress!
Unlock This CourseGeothermal energy is one of the most reliable renewable energy sources available to us. Unlike solar or wind power, it works 24/7, providing constant electricity generation. The word "geothermal" comes from Greek words meaning "earth heat" - and that's exactly what it uses!
Deep beneath our feet, the Earth's core reaches temperatures of over 5,000°C. This incredible heat slowly moves towards the surface, creating opportunities for us to harness this natural energy source. Countries like Iceland get almost all their heating from geothermal sources, whilst places like the Philippines generate significant amounts of electricity from underground heat.
Key Definitions:
The Earth's core is incredibly hot due to radioactive decay and leftover heat from when our planet formed 4.6 billion years ago. This heat moves upwards through the mantle and crust. In some places, underground water gets heated by this process, creating natural hot springs, geysers and steam vents that we can tap into for energy.
There are three main types of geothermal power plants, each designed to work with different underground conditions and temperatures.
These are the oldest and simplest type of geothermal power plant. They use steam that comes directly from underground reservoirs. The steam is piped straight from the ground to turn turbines that generate electricity. The Geysers in California, USA, is the world's largest dry steam field.
Most common type worldwide. Uses high-pressure hot water from underground that "flashes" into steam when pressure drops. The steam drives turbines whilst leftover water gets pumped back underground.
Works with lower temperature water (80-180°C). Hot water heats a secondary fluid with a lower boiling point, which creates vapour to drive turbines. All water stays underground, making it very environmentally friendly.
Creates artificial geothermal reservoirs by pumping water into hot dry rocks. Water is heated as it flows through cracks in the rock, then pumped back up as steam. Still being developed but has huge potential.
Iceland sits on the Mid-Atlantic Ridge, making it a geothermal goldmine. Over 90% of homes are heated using geothermal energy and about 30% of electricity comes from geothermal power plants. The Blue Lagoon spa is actually heated by waste water from a nearby geothermal power plant! Iceland's success shows how countries with the right geology can become almost entirely energy independent using geothermal power.
Geothermal energy isn't available everywhere. The best locations are found along tectonic plate boundaries, particularly around the "Ring of Fire" in the Pacific Ocean. Countries like Indonesia, Philippines, Turkey, New Zealand and parts of the USA have excellent geothermal potential.
The ideal geothermal site needs three things: heat source (magma or hot rocks), water source (underground aquifers) and permeable rock that allows water to flow. Volcanic areas and fault lines often provide these conditions naturally.
The United States leads the world in geothermal electricity generation, followed by Indonesia and the Philippines. However, when looking at percentage of total energy use, Iceland and El Salvador are the champions, getting significant portions of their energy from geothermal sources.
The Philippines is the world's second-largest geothermal producer, generating about 12% of its electricity from underground heat. The country has over 230 volcanoes, providing excellent geothermal potential. The Malitbog geothermal plant in Leyte can power 500,000 homes. However, development faces challenges including high upfront costs, technical expertise requirements and competition from cheaper fossil fuels. The government is working to expand geothermal capacity as part of renewable energy goals.
Geothermal energy offers several compelling benefits that make it an attractive renewable energy option:
Unlike solar or wind, geothermal works 24/7 regardless of weather. Power plants typically achieve 90%+ capacity factors, meaning they generate electricity almost continuously.
Produces minimal greenhouse gases - about 1/8th of a coal plant's emissions. Modern plants release virtually no pollutants into the atmosphere.
High initial costs but very low operating expenses. Plants can run for 50+ years with minimal maintenance, providing stable electricity prices.
Despite its benefits, geothermal energy faces several significant challenges that limit its widespread adoption:
The biggest challenge is geography - geothermal resources are only available in specific locations with the right geological conditions. This means many countries simply cannot access this energy source, unlike solar or wind which are available almost everywhere.
Drilling deep wells and building power plants requires massive upfront investment - often £3-5 million per MW of capacity. Exploration is risky as not all sites prove commercially viable.
While generally environmentally friendly, geothermal development does have some environmental impacts that need careful management:
Removing large amounts of underground water can cause land to sink. Modern plants reinject water to prevent this problem.
High-pressure water injection can sometimes trigger small earthquakes. Careful monitoring and regulation help minimise risks.
Some plants require significant water for cooling. Binary cycle plants are more water-efficient than traditional designs.
The future of geothermal energy looks promising, with new technologies expanding where it can be used. Enhanced Geothermal Systems (EGS) could potentially provide geothermal energy in areas without natural hot springs or steam vents.
Scientists are developing ways to tap into deeper, hotter resources and create artificial geothermal reservoirs. Advanced drilling techniques borrowed from the oil industry are making it possible to reach previously inaccessible heat sources. Some projects are even exploring using geothermal energy for hydrogen production and carbon capture.
The International Energy Agency predicts geothermal capacity could grow by 70% by 2030. Countries like Kenya, Turkey and Indonesia are rapidly expanding their geothermal programmes. As technology improves and costs decrease, geothermal energy could play a much larger role in global renewable energy supply, particularly for providing reliable baseload power to complement variable sources like solar and wind.