To add to this: we can also harvest energy from processes that would happen anyway. Eg solar power and hydro power. The water is going to flow downhill whether there is an electric generator in the way or not. Same for solar panels - whether we capture it and convert it to electrical energy or not makes little difference for the Earth as a whole. We just get a whole bunch of energy "for free" because we're inserting ourselves into a natural process that's ongoing (we do need the apparatus to capture it though).
Nuclear and fossil fuels are similar, but the timescales involved there are far too long for humans. Ie burning coal does have negative side effects because we aren't creating new coal from the carbon in the atmosphere at comparable rates.
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To add to this: we can also harvest energy from processes that would happen anyway. Eg solar power and hydro power. The water is going to flow downhill whether there is an electric generator in the way or not. Same for solar panels - whether we capture it and convert it to electrical energy or not makes little difference for the Earth as a whole. We just get a whole bunch of energy "for free" because we're inserting ourselves into a natural process that's ongoing (we do need the apparatus to capture it though).
Nuclear and fossil fuels are similar, but the timescales involved there are far too long for humans. Ie burning coal does have negative side effects because we aren't creating new coal from the carbon in the atmosphere at comparable rates.