UKERC EDC: Publications

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Abstract:

This project investigates ryegrass as a wet energy crop and is believed to be the first of its kind in the UK. It is hoped that this research will help towards the Government's target to produce 20% of our energy through renewable sources by 2020 in a move towards a carbon neutral economy. The growing of energy crops creates a diversification opportunity for UK farmers with the reform of the Common Agricultural Policy moving away from subsidised farming. Most energy crop development to date has been directed towards the production of low moisture content biomass which is transformed into useful energy by thermal processes. In contract this project examines the harvesting of rye-grass as a high moisture energy crop to be transformed into useful energy by anaerobic digestion.

The key features of such a concept are:

The UK has one of the best climates in the world for growing rye-grass;

The high moisture content of the grass is not a draw-back since anaerobic digestion is a wet process;

The primary constituents of the biogas are only carbon, hydrogen and oxygen;

The wet digestate containing the nutrients, can be returned to the grassland to enhance future crop growth;

Carbon not transformed to biogas may be sequestered into the soil;

The process presents a new opportunity for farm diversification without the need to plant new crops.

In summary, the process has the potential of creating a sustainable cycle, as summarised in the simple flow diagram in Figure 1, where the biogas plant includes a boiler or CHP unit, which produces energy and an exhaust gas.

This project has provided very firm grounding for Greenfinch's current research within Cropgen, A European consortium investigating the production of biogas using agri wastes and energy crops. In Germany, at the time of writing, there are 3000 farm biogas plants being run on crops and agri wastes proving that biogas technology is viable. The reform of the Common Agricultural Policy forcing farmers to grow crops that have real monitory value, combined with the continuing rise in the price of oil, will make anaerobic digestion a real option for energy production

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