Bioenergy and Biofuel Research
Biomass production in Ireland
Ireland is quiet unique in its biomass capacity. Primarily this singularity is associated with the agricultural system; Ireland has 8% of the EU cattle herd with less than 1% of the EU human population. As our livestock are fed grass, this lends itself to the situation whereby 91% of our land is under grass and only 9% of agricultural land is arable. This arable land is fully utilised; grains are required for our alcohol industries and the production of flour. We actually import barley. Thus it may be said that grass is the most ubiquitious feed-stock for bioenergy in Ireland.
Cross compliance does not permit the wholesale conversion of pastureland to arable land. Levels were set as per 2003. Ploughing of pastureland releases carbon stored in the soil. Thus land under grass must stay under grass. Furthermore grass production in temperate oceanic climates such as Ireland is very high, up to 15 tonnes dry matter per hectare per annum. Ireland grows grass better than any other country; in bioenergy grass is where we find our competitive advantage.
The research group has published extensively in Life Cycle Analyses of biofuel systems. The most sustainable biofuels are derived from residues and lignocellulosic feedstocks. We have published on biodiesel, bioethanol and biomethane systems. The Renewable Energy Directive of 60% greenhouse gas reduction on the fossil fuel displaced is a challenging target. For example biomethane generated from grass can meet this level if we account for sequestration of carbon into the soil.
Feedstocks for anaerobic digestion
Ireland has major unexploited sources of natural energy in grass, municipal organic waste and slaughter waste. Anaerobically digested in bioreactors to produce biomethane, this feed-stock can produce gas for the national gas grid. Ireland, with its very high per capita feed-stock volumes, could substitute between 7.5 and 33% of natural gas with biomethane. The biomethane may be distributed in the natural gas grid and be utilised for renewable thermal energy and for transport biofuel. A strategy is proposed whereby 200 digesters of 50,000 t/a scale may be used to treat slurries, slaughter waste, municipal solid waste and grass.
The current research involves the following:
- A Higher Education Authority (HEA) funded project entitled “An evaluation of optimal biofuel in a Northern European Context.”
- A Department of Agricultural Fisheries and Food (DAFF) funded project entitled “GreenGrass: Developing grass for sustainable renewable energy and value added products.” This project has funded the design and construction of large lab scale (300 L) digester systems for use with high solid content feed-stocks (20 – 40%) such as grass
- An Environmental Protection Agency (EPA) funded project entitled “Compressed biomethane generated from grass.” This project funds two post doctorates in full life cycle analyses of both grass production and biomethane production from grass.
- A Bord Gais Eireann (BGE) funded project entitled: “Gaseous Biofuels.” This has an ambition of examining the potential for renewable gas and compressed natural gas (together termed bio-CNG) as transport fuel
The group has published 36 peer review journal papers, 22 peer review conference papers and 16 invited lectures in the last 5 years.
The group has recently invested about €150k on bespoke anaerobic reactors and associated laboratory equipment including for:
- Continuously stirred tank reactor system (CSTR): Two number 300 L reactors connected in sequence with recirculation of leachate, automatic monitoring and downloadable data.
- Sequencing fed leach bed reactors complete with Upflow Anaerobic Sludge Bed Reactor: Six number 17 L leach beds connected to a 36 L collection chamber and a 36 L UASB.
- Two number lab scale (5L) anaerobic reactors.