Assuming there is a demand for energy (given) than generating energy to meet that demand (e.g. by burning coal or gas) has a much larger negative impact I would

Assuming there is a demand for energy (given) than generating energy to meet that demand (e.g. by burning coal or gas) has a much larger negative impact I would imagine. It's sorta like capturing braking energy. This used to be dissipated as heat but now can be turned into energy which improves MPG and therefore reduces the need for fossil fuels, no?