What's over 7 kilometres tall and dangles into the North Sea? According to researchers in the Netherlands, it could be MegaPower—an enormous power station which they claim may one day be a major source of pollution-free energy. While the scheme may sound crazy, the working cycle that the tower would use to generate electricity is similar to the cycle that underlies hydroelectric power. The turbines in a hydroelectric power station harness the potential energy of water as it falls from a lake or reservoir towards the sea. But this is only half the story. The water gained this potential energy when it evaporated from the ocean and rose into the clouds. There it cools down and condenses to form rain that replenishes the lakes.
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