Assessment of the availability of agricultural crop residues in the European Union: Potential and limitations for bioenergy use
Introduction
The new European Union Directive on the promotion of the use of energy from renewable sources (Directive 2009/28/EC of 23 April 2009), includes a binding target of a 20% share of renewable energy in energy consumption in EU and differentiated national overall targets by 2020. The use of biomass for transport fuel, heat and electricity production will have to increase substantially in order to meet the proposed binding target of renewable energy in the EU energy mix of 20% by 2020.
Biomass is expected to contribute to around two-thirds of the renewable energy share in 2020 according to projections (European Commission, 2009). Therefore, the use of biomass for bioenergy production must consider the use of all available resources in a sustainable way, without causing negative impacts. The different residues resulting from the production of agricultural crops might contribute to the achievement of the renewable energy targets, as proposed for 2020.
There are several studies providing the biomass assessment potential, at EU or world level, including different biomass resources – forestry, agriculture and/or waste. As bioenergy development provides new opportunities for using agricultural crop residues, this paper proposes an estimation of the currently available biomass residues from agricultural crop production at EU and Member State level, based on a comprehensive analysis. The main agricultural crops were included in the study: wheat, barley, oats, rye, rice, maize, sunflower and rapeseed, based on present production and agricultural practices. The assessment was based on actual crop production, sustainable removal rates from land and current competitive uses of residues. Crop production and yields, multi-annual yield variation for each crop and the specific residues to product ratios, depending on the crop type and crop yield were all included as the most important factors that must be considered.
Since there is a large annual variation in the crop production, the amount of agricultural crop residues varies significantly. Therefore, this paper proposes an estimate of the average, minimum and maximum amounts of residues, to consider this yearly variability, detailed at Member States level.
Section snippets
Crop residue production and yearly variation
In the European Union, here are large differences in terms of cultivated area, types of crops and yields, due to the climate conditions, specific soil condition and farming practices between Member States. Cereals and oilseeds are important crops, in terms of area cultivated and production (Fig. 1). Annual crops are quite variable in yield from one year to another, particularly at a local level, depending on precipitations in rain-fed conditions that lead to a variability in the crop residues
Methodology for estimating crop residue availability
In order to provide estimates of the crop residues that can be used for bioenergy production, this paper takes into account the crop production and residue production, environmental constraints for collection and their competitive uses (Edwards et al., 2005), depending on the livestock sector and animal population (cattle, horses, and sheep), or horticulture/mushroom production.
Therefore, the estimate of the agricultural crop residues was done taking into account:
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types of crops and area of crop
Crop residue production
Crop residue yields were calculated using the residue-to-product ratio, depending on crop yield proposed in this paper for all countries. Crop residue production was afterward established based crop residue yields and crop acreage. The main data on the range of residue-to-crop ratio, availability, seed and straw moisture content used in the calculations are presented in Table 4.
The total amount of crop residues produced in EU27 every year was estimated at 258 M dry tonnes/year on average, based
Discussion and recommendations
The estimates of the agricultural crop residues in EU27 show that they are produced and are available to be used for energy production in large quantities and could therefore play an important role for sustainable energy production. There are good opportunities but also limitations for the use of crop residues for bioenergy.
There are a number of issues that must be considered: resources (quantity, multi-annual yield variation), logistics (energy demand in the area, storage, security of supply,
Conclusions
This study revealed that important amounts of agricultural crop residues are available in the EU, estimated at 1530 PJ/year, on average, which can be used in a sustainable way for bioenergy production. Important amounts of crop residues are available in France, Germany, Romania, Spain, Italy, Hungary, Poland, etc.
However, the results show large spatial and temporal variations at EU27 level, between 1090 and 1900 PJ/year. This yearly variation of crop residue ranges between +23% and −28% compared
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