As the global energy sector shifts toward renewables, geothermal power, often overlooked, is quietly proving to be one of the most reliable and sustainable sources available. Unlike wind and solar, geothermal delivers a consistent 24/7 baseload energy. Two countries have emerged as leaders, Iceland and Kenya. Iceland’s Hellisheiði Power Plant and Kenya’s Olkaria Geothermal Complex demonstrate how engineering ingenuity can unlock earth’s natural heat − cleanly, safely and at scale.
Engineering at the edge of a volcano
Located on the volcanically active Hengill ridge just outside Reykjavík, the Hellisheiði plant is one of the world’s most advanced geothermal facilities. It has been in operation since 2006 and produces 303 MW of electricity and 133 MW of thermal energy, powering homes and heating buildings across the region.
The plant’s wells, some over 3000 metres deep, tap into high-temperature reservoirs exceeding 300°C. Steam extracted from these depths drives turbines, and the separated hot water is piped into Reykjavik’s extensive district heating system. To maintain pressure and sustainability, the spent fluid is reinjected underground.
The key to the Hellisheiði project is its CarbFix carbon capture system. Although geothermal is low-emission, small amounts of CO₂ and hydrogen sulphide are released from underground gases. CarbFix addresses this by dissolving CO₂ in water and injecting it into basalt rock layers, where it reacts with minerals and turns to solid carbonate in under two years. This pioneering process captures and stores over 90% of the plant’s CO₂ emissions, offering a scalable model for sustainability, with low operational costs and minimal infrastructure.
Powering a nation from the Rift
Thousands of kilometres south in Kenya’s Great Rift Valley, another geothermal success story is unfolding. The Olkaria Geothermal Complex, operated by KenGen, is the largest geothermal power project in Africa, currently generating over 850 MW, with further expansion underway.
Olkaria’s growth has been steady since the 1980s, but recent investments have accelerated its development. The latest station, Olkaria V, which was commissioned in 2019, features air-cooled condensers to reduce water use and two 82,7 MW turbines. Meanwhile, Olkaria III, run by private operator OrPower, was Africa’s first privately financed geothermal plant.
The wells, up to 3500 metres deep, tap into steam-rich reservoirs ideal for direct steam and binary cycle systems. Drilling requires advanced subsurface mapping, real-time monitoring and careful pressure management to avoid reservoir degradation. Pipelines feed steam to turbines that run day and night, unaffected by rainfall or daylight.
But Kenya’s geothermal success isn’t just technical, it’s also social. During expansion of Olkaria IV, KenGen resettled nearby Maasai communities into new model villages, complete with schools, water and infrastructure. The relocation, widely praised by the World Bank, is now held up as a best-practice example of socially responsible engineering.
Shared lessons across continents
Despite their differences, Hellisheiði and Olkaria offer similar takeaways:
• Stable baseload power: Unlike solar and wind, geothermal runs continuously, making it ideal for national grids.
• Deep engineering: Both plants rely on advanced drilling and reinjection techniques to manage pressure and temperature in demanding geological conditions.
• Environmental innovation: CarbFix in Iceland and low-water cooling in Kenya show how geothermal can be made even cleaner.
• Community and training: Kenya’s Geothermal Training Centre and Iceland’s academic partnerships are building skills for the global south and exporting expertise.
Both countries are now seen as global leaders. Kenya is expanding Olkaria toward a 1500 MW target by 2030. Iceland, with nearly 100% renewable electricity already, is exporting its know-how to East Africa and Asia.
The global opportunity
Geothermal currently supplies less than 1% of global electricity, yet its untapped potential is vast. The East African Rift could yield over 20 GW, while enhanced geothermal systems promise to make previously inaccessible regions viable.
The challenge is to attract early-stage investment. Drilling is expensive and resource uncertainty is high. But as climate goals tighten, geothermal’s reliability and low emissions make it an increasingly attractive option.
A resource beneath our feet
Hellisheiði and Olkaria show that geothermal isn’t just a niche resource, it’s a foundation for clean energy resilience. Engineers are proving that the earth’s natural heat can power a better future − quietly, consistently and sustainably. Geothermal is a critical tool in the global energy toolkit.
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