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 unit of power. In the International System of Units (SI) it is defined as a derived unit of 1 joule per second,[1] and is used to quantify the rate of energy transfer. In dimensional analysis it is described by    M L  2   T  − 3   {\displaystyle {\mathsf {ML}}^{2}{\mathsf {T}}^{-3}} .[2]