Improving the efficiency of feedstock production, conversion and use helps increase resource productivity and thereby reduce pressure on land, water and other resources. Increasing yields and optimising agricultural production can augment output on existing cropland without encroaching on natural land. This is particularly relevant in developing countries where there is significant potential to increase crop and land productivity. There is also scope for harnessing investments in biofuels development to modernise the agricultural sector and help build capacity, which can promote overall agriculture production for food, materials and fuel.
Different biofuels pathways have different efficiencies in the growth of feedstocks, conversion processes and end-uses. This chain of efficiency pertaining to input and output needs to be considered in national planning processes to identify the most suitable biofuel feedstocks for a given country, region and local context. For example, the energy potential of landfill material is released through combustion, whereas bioethanol, (both from crops such as corn and wheat, and from cellulose such as grass and wood) is obtained through conversion.
The development of biorefineries can greatly support efforts to increase resource efficiency. Biorefineries integrate biomass conversion processes and equipment to produce fuel, power, and chemicals from biomass. By producing multiple
Energy potential from one tonne input: organic matter and landfill material Tonnes of oil equivalent
Wheat 0.15 Bioethanol
0.15 0.05 Grass 0.19 Wood 0.18
0.16 Hay 0.15 0.84 0.34
products, a biorefinery can take advantage of the differences in biomass components and intermediate products, thus maximising the value of a biomass feedstock (Figure 4.5).
Increasing the productivity of biorefineries is a vital part of the bioenergy supply chain. Interconnected closed biorefinery systems can capture waste products and integrate them back into the biorefinery process. Such measures to increase efficiency contribute to reducing GHG emissions from decomposing biorefinery waste, and to creating other value-added products.
Decreasing the overall use of water in biorefineries is also essential. Incorporating grey water systems, which re-circulate used water can reduce the water footprint of some feedstocks.
Construction and demolition timber
Paper Prunings 0.24
inorganics Food wastes
Other 0.19 0.62 Cellulosic bioethanolOrganic residues and waste
Notes: 1. Values for selected sources are calculated considering the maximum output for each one, output varying with the technology used.
2. Estimates for landfill materials based on a Californian case study. 3. Energy from bioethanol obtained from conversion. Energy from landfill materials obtained by combustion.
Figure 4.4 Energy potential from one tonne input: organic matter and landfi ll material
Sources: California Integrated Waste Management Board, 2006; IEA, 2004; Bioenergy Feedstock Information Network, Biomass Research and Development.