Njoki Kangethe
When you think of electricity in Africa, what comes to mind? Solar panels glinting on rooftops? Big dams on wide rivers? Perhaps the hum of diesel generators in towns and villages?
But here’s a less familiar source: heat from beneath our feet. Yes, you read that right.
Kenya, for example, powers millions of homes and industries using steam that rises from deep inside the earth (around 47% of Kenya’s total electricity supply). This is geothermal energy, and it’s one of the most promising tools Africa has to secure a clean, reliable energy future.
Yet for most people, geothermal feels like a mystery. How exactly does it work? Why is it so important? And why should all citizens, not just engineers or policy makers, understand it?
Let’s break it down.
The Science Made Simple
The earth is somewhat like a giant oven.
Beneath the crust, heat is stored in hot rocks, boiling water, and underground reservoirs. In places where this heat is close enough to the surface, often along the Rift Valley, it can be tapped for energy.
The East African Rift Valley is one of the best places on Earth to tap geothermal energy because it sits on divergent tectonic plates where the earth’s crust is thinning and pulling apart. This allows heat from deep within the mantle to rise closer to the surface, where it interacts with underground rocks and water. The result is naturally occurring reservoirs of steam and hot water, perfect for drilling wells and generating electricity.
Here’s how it works:
1. Drilling Wells; Engineers drill deep into the ground, sometimes over two kilometers down, to reach superheated water or steam.
2. Capturing the Steam; That steam is piped to the surface.
3. Turning the Turbine; The pressure of the steam spins large turbines, which generate electricity.
4. Recycling the Water; After use, the water is cooled and pumped back underground, ready to be heated again.
It’s basically a natural cycle: earth heats the water, we use the steam for power, and then, we return the water to the ground. Unlike coal or oil, there’s no burning, no smoke, and far fewer emissions.
Why This Matters for Africa
So why should we care about geothermal, especially when Africa is already pushing solar, wind, and even nuclear projects?
• It’s reliable. Unlike solar, which depends on sunshine, or wind, which depends on weather, geothermal runs 24/7. Rain or shine, day or night, it keeps producing electricity.
• It’s clean. Geothermal drastically reduces greenhouse gas emissions compared to fossil fuels. For countries facing climate risks, this is crucial.
• It’s local. Africa has some of the richest geothermal potential in the world, particularly along the Rift Valley in Kenya, Ethiopia, Djibouti, and Tanzania. That means energy independence; no need to import expensive fuel.
• It’s long-term affordable. Yes, the upfront investment is big (drilling deep wells isn’t cheap), but once a plant is built, running costs are low. Over decades, that makes it one of the cheapest energy sources available.
Kenya is the continent’s leader, with over 860 MW of installed geothermal capacity, making up nearly half of its electricity supply. That means Kenya has already shown what’s possible, and why geothermal deserves attention.
Why Simplifying the Science Matters
Here’s the thing: energy debates often skip straight to policies, debt, or deals. But many people don’t understand how these systems actually work. Without that foundation, conversations about ‘geothermal versus nuclear’ or ‘financing energy projects’feel distant and abstract.
That’s why science communication matters.
Explaining geothermal in plain language helps citizens, journalists, and community leaders join the conversation. Because energy isn’t just about engineers and presidents signing contracts; it’s about families who need light for homework, clinics that need power for vaccines, and welders who need electricity to join materials.
When people understand the basics, they can ask better questions:
• Where will plants be built?
• Who benefits from the electricity?
• Are communities being consulted?
• How does this compare to other options like solar or wind?
Knowledge is power, quite literally.
Everyday Impact
Think about it: in parts of Kenya’s Rift Valley, geothermal keeps lights on in homes, powers industries in Nairobi, and reduces blackouts during drought years when hydropower dips.
That reliability matters. It means schoolchildren aren’t stuck doing homework by candlelight. It means hospitals don’t have to rely on noisy, polluting diesel generators. It means factories can keep running without costly interruptions.
This is why geothermal isn’t just a technical solution. It’s a social one.
What Comes Next
This article is just a starting point; a primer of sorts. Now that you know how geothermal works, we can explore the deeper questions in upcoming pieces:
• Economics: How much does it cost to build, and who’s financing it?
• Opportunities: How can Africa expand geothermal to other countries?
• Policy: What role should governments play, and what lessons can be learned from Kenya’s success?
Because geothermal isn’t just Kenya’s story. Ethiopia has big plans, Djibouti is scaling up, and other African countries are exploring their potential. With the right investment and policies, geothermal could light up millions of homes across the continent.
Closing Thought
Africa is standing at a crossroads. We can continue importing fossil fuels, or we can embrace what lies beneath our feet.
Geothermal energy isn’t the only answer, but it’s a powerful part of the mix. And understanding it, simply, clearly, and without jargon, is the first step to making sure decisions are made with people, not just politicians, in mind.
Because the heat is already there, waiting.
References
• Kenya Electricity Generating Company (KenGen, 2023), Annual Report & Geothermal Capacity.
• International Renewable Energy Agency (IRENA, 2022), Renewable Power Generation Costs.
• African Development Bank (AfDB, 2021), Geothermal Development in Africa.
• World Bank (WB, 2022), Scaling Up Geothermal in Africa.
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