Comparison of renewable fuels based on their land use using energy densities

In this article energy densities of selected renewable fuels are determined. Energy density is defined here as the annual energy production per hectare, taking energy inputs into account. Using 5 scenarios, consisting of 1 set focusing on technical differences and 1 set focusing on geographical variations, the range of energy densities currently obtained in Europe was determined for the following fuels: biodiesel from rapeseed; bioethanol from sugar beet; electricity from wood, wind and solar PV. The energy densities of the fuels produced from biomass were calculated by determining the energy contained in the energy carrier produced from the crop annually produced on 1 ha, from which the energy inputs for crop cultivation and conversion were subtracted. For wind and solar electricity, the energy density calculation was based on the energy production per turbine or cell and the number of turbines or cells per hectare after which the manufacturing energy was subtracted. Comparing the results shows that, for the average energy density scenarios, the ratio between the energy densities for wind, solar, and biomass is approximately 100:42:1, with wind electricity also having the highest energy output/input ratio. A case study was done in which the energy density was used to calculate the distance a vehicle can cover using the energy carrier annually produced per hectare. This was done for 3 regions, in Mid-Sweden, North-Netherlands, and South-East Spain. The results of the case show that wind electricity results in the largest distance covered, except in Spain, where solar electricity is the most favourable option.