# What happens to heat waste produced by energy generation?

What happens to heat waste produced by energy generation on earth that must be there according to the laws of thermodynamics? So, it never dissipates and remains on earth?

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–  EnergyNumbers Jan 13 '13 at 12:21

Take for example a conventional coal fired power plant as used widely in most countries.

About 40% of the energy from burning the coal is converted to electricity, and the remaining 60% is lost as heat to the environment.

The 40% of the energy that gets converted to heat is used by us consumers and eventually gets converted to heat and is lost as heat to the environment.

So all the energy used by burning coal (or gas, or from nuclear energy) eventually ends up in the environment, where it heats up the air/rivers/seas/whatever. However the amount of heat lost to the environment is small compared to the amount received from the Sun and generated inside the Earth.

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This is correct, but for completeness it's important to note that the Earth also gives off thermal radiation, so the waste heat doesn't exactly stay in the Earth system, but will eventually be lost to space in the form of infra-red light. –  Nathaniel Jan 13 '13 at 11:46
Nathaniel, I would agree to your comment. But we know from astronomy that the atmosphere is absorbing most of the infrared light. So, from this starting point, I would say only a fraction of the thermal radiation of earth escapes to space. Which is very surprising to me. –  elcojon Jan 13 '13 at 12:04
@elcojon Remember that if the atmosphere absorbs infrared light, it will also emit infrared light. When someone says "earth gives off thermal radiation" they generally think of the atmosphere as a part of earth. –  jkej Jan 13 '13 at 12:16
almost all the energy ends up in the environment at human timescales: some of it (a pretty small proportion) gets embodied in chemical bonds and even gravitational potential –  EnergyNumbers Jan 13 '13 at 12:24

The energy does not necessarily remain on earth. Earth maintains an energy balance with its surroundings. The sum of the energy reaching earth through radiation and the energy produced on earth must match the energy leaving earth through radiation. If the latter is too low, earth will warm up, thereby increasing its blackbody radiation and restoring the balance.

However, the energy production on earth (including the production in the core) is generally an extremely small term in this equation.

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The heat generated by combustion of fossil fuels is slowly building in the environment. Contrary to atmospheric degradation theories. We have gone from a half a million camp fires to burning billions of gallons of oil.

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Actually the heat from fossil fuel burning is not the problem at all. The Earth absorbs way more energy from the Sun. The issue is the buildup of CO2 and other greenhouse gases that cause the Earth to trap heat instead of radiating it out into space. –  Brandon Enright Dec 19 '14 at 1:08