8. Lake Power

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Although it seems like an unlikely source of energy, some lakes in the world have massive volumes of methane gas trapped in their depths by the differences in water temperature and density in different levels of the lake. Sometimes changing conditions in the lake cause the gas to be freed, which can bubble up to the surface violently, which can kill both fish, animals and people in the area by suffocating them. A lake called Lake Kivu in the African Nation of Rwanda is a prime candidate for this kind of event, and that is exactly why a power plant was built nearby which siphons gas off from the lakes depths to produce electricity.