TITLE:
Evaluation of the Effect of Agricultural Management on Energy Yield and Greenhouse Gas Emission Reduction of Bioenergy Production Chains
AUTHORS:
Sjaak Conijn, Wim Corré, Hans Langeveld, Jacques Davies
KEYWORDS:
Energy Crops, Biodiesel, Bioethanol, Bioelectricity, Sustainable Production, Energy Yield, Greenhouse Gas Emission
JOURNAL NAME:
Natural Resources,
Vol.5 No.7,
May
29,
2014
ABSTRACT:
The role of energy crops in reducing fossil energy use and greenhouse
gas emission is much debated. To improve decision making on the use of crops
for producing bioenergy, a tool (Energy Crop Simulation Model or E-CROP) has
been developed to calculate 1) sustainable crop dry matter yield levels as
function of agricultural inputs, and 2) gross and net energy yield and
greenhouse gas emission reduction, covering the entire bioenergy production
chain from sowing to distribution of bioenergy. E-CROP can be applied to a wide
range of crops, soils, climatic conditions, management choices, and conversion
technologies. This paper describes E-CROP and focuses on its application on
four arable crops, as 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 (viz.
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-1. Lowering irrigation and/or fertilisation input
levels generally resulted in a reduction of net energy yields. The net
reduction of greenhouse gas emissions in the average situation ranged from 0.60
to 6.5 t CO2-eq.ha-1. In general, N2O emission from
nitrogen fertiliser caused large variations in the net reduction of greenhouse
gas emission, which even became negative in some situations. Lowering nitrogen
fertilisation to levels that are suboptimal for net energy yields enhanced the
net reduction in greenhouse gas emission, implicating that both goals cannot be
optimised simultaneously. Agricultural knowledge is important for optimising
the outputs of bioenergy production chains.