<em>Thermal power, Wind power, Solar energy and Nuclear power are most often used to generate the power around the world.
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<u>Explanation:</u>
Thermal power produced by the burning of coal. There are few high grade coal regions around the world, remaining are low grade category and lowcalorific value. Thermal power station pollutes the environment heavily and coal reserves are gradually decreasing in trend. So more countries lead to the renewable energy such as Solar and Wind energy. These energy are unlimited and eco friendly. Another hand, Nuclear power are generated using Uranium and Thorium, but wastage from Nuclear reactors tends to be highly radiative and affect the land and sea ecosystem.
Greenhouse effect is the trapping of the sun's warmth in a planet's lower atmosphere, due to the greater transparency of the atmosphere to visible radiation from the sun than to infrared radiation emitted from the planet's surface.
If the rotation period slowed to 1 rotation every 365 days a condition called 'sun synchronous', every spot in the Earth would have permanent daytime or nighttime all year long.