Department of Agriculture and Food (DAFF) Stimulus Fund

Department of Agriculture and Food (DAFF) Stimulus

Department of Agriculture and Food (DAFF) Stimulus
GREENGRASS: Developing grass for sustainable renewable energy generation and value-added products

Lead PI: Dr Jerry D Murphy

Research Assistant/PhD : Abdul-Sattar Nizami

Duration of research: 2008-2010

Project description:

Crops grown specifically for renewable energy production and other novel uses offer opportunities for sustainable agricultural systems. Where this involves marginal land or grassland use, new economic potential can be realised. This project will investigate the potential utilisation of grass for the production of biobased products and biofuel.

Forage grass is a hardy perennial crop which does not require rotation, is well understood by farmers, and if used as an energy crop, neither impedes on arable land nor requires new agricultural practices. Different grass species will be grown and harvested under varying management conditions and ensiled. Effect of growth stage on the composition of the various treatments will be assessed. The silage will be chemically analysed and separated resulting in two material streams (fibre and separated liquid). The fibre will be characterised and its use as a biobased (insulation) material will be assessed.

Biogas production from the separated liquid and silage will be compared. Biogas generated from ensiled grass has the potential to reduce the land requirement to meet the Biofuels Directive fourfold, when compared to biodiesel from rape seed. Biogas yields may be improved and digester size reduced through optimisation of the digester configuration and hydrolytic pretreatment of grass.

Work package 3: Initial literature review on digester design for grass feedstocks.


  • Identify appropriate anaerobic digestion technologies suitable for grass/silage digestion.

  • Identify scales which are applicable or suitable to Irish farms.

  • Generate a plant design for lab scale and small demonstration scale.

  • Postulate a farm scale biogas from grass system.

  • Determine gross and net energy production depending on systems employed.

  • Optimise logistics of system (transport, digestate, biogas use).

Work package 4: Laboratory comparison of digester design and operation


  • Determine the potential biogas/CH4 production per unit of energy crop

  • Compare performance data for differing digester designs

  • Determine the optimum residence time of the feedstock in the digester

  • Explore the effect of biomass pre-treatment on the process in terms of gross and net energy production.

Publications from project:

Peer review journal publications

Under review:

  1. Nicholas E. Korres, Anoop Singh, Abdul-Sattar Nizamia, Jerry D. Murphy. “Is grass biomethane the most sustainable indigenous European transport biofuel? Submitted to Renewable Energy, September 2009.

  2. AS Nizami, N E Korres, JD Murphy; “A review of the integrated process for the production of grass biomethane,” submitted to Environmental Science and Technology, May 2009 (in communication).

  3. AS Nizami, JD Murphy; “What is the optimal digester configuration for producing grass biomethane?” submitted to Renewable Energy, December 2008.


  1. Smyth BM, Murphy JD, O'Brien C. 2009. What is the energy balance of grass biomethane in Ireland and other temperate northern European climates? Renewable and Sustainable Energy Reviews doi:10.1016/j.rser.2009.04.03

Peer review conference papers:

  1. JD Murphy, B Smyth, AS Nizami , T Thamsiriroj, A Singh, N Korres; “The potential for biomethane as a transport fuel in Ireland,” In: Biofuels Directive to bio based Transport Systems in 2020, IEA Bioenergy Task 39 Subtask Policy and Implementation Workshop, Dresden, Germany, June 2-5, 2009.

  2. N E. Korres, C O’Brien, B Smyth, AS Nizami, T Thamisirioj, R Schulte, JD Murphy; “A preliminary analysis of energy balance and greenhouse gas (GHG) emissions of biomethane production as a transport fuel from grass/silage. A case study for Ireland,” Society of Environmental Toxicology and Chemistry (SETAC) Conference, Goteborg, Sweden, 31 May – 4 June 2009.

  3. JD Murphy; “Using Grass to reduce emissions in the agriculture and transport sectors,” In: The Greening of Irish Agriculture, Responding to the Challenge of Climate Change, Institute of International and European Affairs (IIEA), Dublin Castle, Jan 9, 2009.

  4. JD Murphy; “Biomethane: A method of generating biofuel from first generation biofuel residues, from stillage and from grass,” Keynote Lecture, First International Symposium for Young Scientist and Technologists in Malting, Brewing and Distilling, University College Cork, 7 November 2008

  5. JD Murphy; “Biomethane: an optimal transport fuel and a method of improving first generation biofuel systems,” International Energy Agency Biofuels Symposium, University College Cork, September 14 th , 2008.

Close X