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Geothermal energy. It’s an abundant source of energy and is produced by tapping the earth’s heat. The closer the heat is to the earth’s surface, the cheaper and easier it is to harness. Dr Scott Tinker reports from the world’s hot spots.

"Geothermal energy, the heat of the earth, can be found beneath our feet everywhere. But extracting enough of it, at an affordable price, is the challenge. In some parts of the world, extreme heat from deep within the earth rises nearer the surface. Here, it’s fairly easy to tap. For more on how that’s done, see our geothermal site visit.

We use that heat in mainly two ways. To heat people’s homes. And to turn a steam turbine, to make electricity. Like hydropower, geothermal electricity is flexible. It can be always-on baseload power, or can be ramped up quickly to follow demand. The problem is, these high temperature geothermal areas are few and far between. Iceland is the best example, but Indonesia, Italy, California and Hawaii all have a powerful geothermal resource.

So how do we get these benefits elsewhere? In some places, old oil wells allow access to hot water. In others, we’re experimenting with drilling new wells, fracturing the rocks and circulating water. But the energy returned is low, while the cost is high. There’s also ‘low temperature geothermal,’ which uses the constant temperature of the near-surface.
But the installation is 3 to 5 times as expensive as conventional equipment.

So that’s geothermal in a nutshell. Where there’s high temperature near the surface, it’s a fantastic resource. Elsewhere it’s still cost prohibitive."

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