Critical conversion efficiency of light energy of the photocatalytic hydrogen production from water decomposition

The idea of the critical conversion efficiency is suggested to improve the conversion efficiency of light energy.The critical conversion efficiency is defined as the conversion efficiency of light energy when the hydrogen energy output is equal to the energy input from the outside system.The energy profit cannot be achieved until the conversion efficiency of light energy is greater than the critical value.A system with Na_2S/Na_2SO_3 as sacrificial reagent is analyzed and calculated.The results show that the critical conversion efficiency of light energy reaches 13% when the annual hydrogen production is 20,000 tons.