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Can renewable energy sources power the world?
Can renewable energy sources power the world?

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6.1 Non-solar renewables

There are also two other sources of renewable energy that do not depend on solar radiation:

Tidal energy

Tidal energy is often confused with wave energy, but its origins are quite different, as this short video clip shows.

Download this video clip.Video player: wave_and_tidal_power_hq_640.mp4
Interactive feature not available in single page view (see it in standard view).

Ocean tides are caused by the gravitational pull of the Moon (with a small contribution from the Sun’s gravity) on the world’s oceans, causing a regular rise and fall in water levels as the Earth rotates. The power of the resulting tides can be harnessed by building a low dam or ‘barrage’, behind which the rising waters are captured and then allowed to flow back through electricity-generating turbines.

Strong underwater currents found in some locations are mainly tidal in origin. After many years of research, development and commissioning, the world’s first commercial tidal stream business, MeyGen, started operations in 2016. See Figure 13. (Atlantis Resources, 2017)

A MayGen marine current turbine (an underwater windmill)
Figure 12 A MayGen marine current turbine (an underwater windmill)

Geothermal energy

Geothermal energy is heat from deep within the Earth, which in some locations heats rocks near the surface. These can heat water in underground aquifers (water bearing rocks), producing hot water that can be used for heating purposes, or in some cases to produce steam for electricity generation.

Watch the video ‘Geothermal Energy’ to learn more:

Download this video clip.Video player: geothermal_energy_hq_640.mp4
Interactive feature not available in single page view (see it in standard view).

In this short course we have decided to concentrate on the solar direct and solar indirect renewables, omitting further detailed coverage of tidal and geothermal energy.