Growing Grass for a Green Biorefinery - An Option for Ireland?
The need to reduce atmospheric greenhouse gas emissions and dependency on fossil fuels has been one of the main driving forces towards the use of renewable resources for energy and chemicals.
Researchers at Teagasc, in association with Wageningen University and Research Centre, The Netherlands, have been looking into the possible use of grassland biomass for the production of energy and chemicals, or green biorefinery (GBR), and have detailed their results in an article in TResearch, Teagasc’s Science magazine.
"The basic principles of a green biorefinery are similar to an oil refinery but, instead of oil, grass or silage is used as the raw material for the production of a variety of products," explains Dr Padraig O’Kiely, Teagasc Animal & Grassland Research and Innovation Centre. "The development of an Irish green biorefinery industry is coherent with the EU Biofuel Directive and the EU’s strategy to develop a 'knowledge-based bio-economy'," says Dr O’Kiely.
The researchers carried out a scoping study based on data and knowledge from the operation of GBRs in Europe and, combined with new Irish data on grass quality, assessed the economic, technical and environmental feasibility of a GBR in an Irish context, which they used to develop a blueprint for a first-generation GBR.
Results from the study suggested that the ideal catchment area for a GBR was 700-800ha depending on biomass availability within the catchment area, and the availability should be in excess of 30 per cent in order to contain transport costs. In terms of suitable locations, Dr O’Kiely said: "In general, the viability of GBR will be highest in areas that have experienced declining livestock numbers and lower farm income, particularly, but not exclusively, areas that support a higher proportion of non-dairy farms. These areas have a higher potential availability of surplus grass biomass. This would mean that the GBR would not have to compete with the traditional agricultural commodities, but rather would provide potential supplementary income to farmers".
Following on from this study, the researchers recently obtained funding from the Department of Agriculture, Fisheries and Food to carry out further work to investigate the potential of different grass species and red clover to produce biomass either as a fresh crop or as silage; the potential of these species to provide fibre that could be used industrially; and, the potential of these species to produce biomethane in anaerobic digestion systems.
Other partners in this ongoing project are University College Cork (UCC) and Queen’s University Belfast (QUB). The group at UCC is developing optimal pilot-scale anaerobic digesters for producing biomethane from grass silage, while the group at QUB is investigating how alternative treatments of the silage immediately prior to anaerobic digestion could improve the biomethane yield.