Marginal grassland has potential for AD

Vast areas of marginal grassland across the UK could be harnessed for use in anaerobic digestion plants.

Farmers and landowners are missing a trick by not considering grass as a potential AD plant feedstock, says AD specialist EnviTec Biogas UK.

“Growing grass to feed AD plants is a real opportunity for some farmers to increase revenues and for the politicians to introduce more stretching biogas targets. It also addresses some of the environmental effects of current farming practice,” said managing director Mike McLaughlin.

“The crop and the machinery to deal with it are already there. In the right circumstances we can make better use of marginal land, add a new revenue stream to the farm, control energy prices, comply with NVZ legislation and improve land quality – all at the same time.”

One tonne of grass was worth about 1,100kWh of primary energy – this means a 250kW biogas plant could be powered by 4,800t of grass a year, he said.

This would benefit farmers in terms of electricity and heat production, which could be used on farm or sold to the grid, as well as the use of the digestate produced as a fertiliser and soil conditioner.

“Recycling the N, P and K and remaining dry matter back into the land improves productivity, land quality and land values. This process is already used for land reclamation,” added Mr McLaughlin. “But to unlock this value, we need to take a step back so we see the wood, not the trees.”

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