A team of researchers of Wageningen University and Research Centre and Biomass Research developed a tool (Energy Crop Simulation Model or E-CROP) to calculate sustainable crop yield levels and (gross and net) energy yield and Greenhouse Gas (GHG) emission reduction. The model covers the entire production chain from sowing to distribution of bioenergy. Their paper describes E-CROP application on four crops, cultivated on two contrasting sites in the Netherlands (potato and sugar beet for bioethanol, winter oilseed rape for biodiesel and silage maize for bioelectricity) and on the effect of crop management (irrigation and nitrogen fertilisation).
In all situations, gross energy output exceeded total energy input. Calculated for an average situation, net energy yield ranged from 45 to 140 GJ∙ha. Net reduction of greenhouse gas emissions in the average situation ranged from 0.60 to 6.5 t CO2-eq per hectare.
Reducing irrigation and/or fertilisation input levels caused large variations in the net reduction of GHG emission, which even be- came negative in some situations. Lowering nitrogen fertilisation reduced yield levels but enhanced the net reduction in GHG emissions. Agricultural knowledge is important for optimising the outputs of bioenergy production chains.