what is a comparison of energy output with energy input
Energy conversion efficiency Energy conversion efficiency (Î·) is the ratio between the useful output of an energy conversion machine and the input, in energy terms. The input, as well as the useful output may be chemical, electric power, mechanical work, light (radiation), or heat.[citation needed]
Watt The watt (symbol: W) is a derived unit of power in the International System of Units (SI) defined as 1 joule per second[1] and can be used to quantify the rate of energy transfer. Power has dimensions of    M L  2   T  − 3   {\displaystyle {\mathsf {ML}}^{2}{\mathsf {T}}^{-3}} .