生物质能源价值评价方法

Present evaluation of biofuel gives little positive to negative net energy value of corn ethanol. It caused a lot of debates about the energy return on investment of ethanol. We redefine and evaluate Net Energy Value (NEV) of bioethanol, based on the energy input data in literature after changing the usage of the unfermented residue to simulate the future which maximizes the energy value of the biomass; and the energy is sorted as fuel, heat and electricity to solve the quality difference of input energy. We estimate NEV from 14 studies about bioethanol and petroleum. The results show that the net energy value for all bioethanol is very positive and not greatly influenced by single factor, but increase at low ethanol yield of biomass. It supports to develop biofuel for our energy and environmental goals and indicates that the net energy yield of unit land is very important parameter to evaluate the biofuel. We should develop a crop with high net energy yield of unit land to decrease land demand for energy production, and the crop can grow in agricultural marginal land with little or no fertilizer without competing with food production.