The Government and farmers must do more to unlock the potential of marginal areas in the UK, it has been claimed.
Anaerobic digestion (AD) specialist EnviTec Biogas UK believes marginal grassland represents an opportunity for farmers to increase revenues significantly.
But the "pointless" food versus energy debate and unambitious biogas targets are hampering farmers' ability to tap into income from AD plants or the production of AD plant feedstocks.
And EnviTec managing director Mike McLaughlin is urging politicians and farming leaders to look at the bigger picture to make the most of marginal areas.
Mr McLaughlin said: "If you do the maths, you realise we're in danger of missing a trick.
"A significant area of land in the UK – especially in Scotland, the North of England and Wales – is only suitable for grass, so it seems crazy not to explore that crop's huge potential.
"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 impacts of current farming practice.
"The crop is already there and the machinery to deal with the crop is 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."
A tonne of grass contains around 1,100kWHr of primary energy, which means about 4,800tonnes a year would be enough to feed a biogas plant producing 250kW of electrical energy.
That electricity can be used on the farm or exported to the grid. If the existing farm enterprise also uses heat, then up to 100kW of hot water can also be supplied from the cooling system on the biogas plant CHP.
The digestate produced by the AD plant, which is almost odourless slurry, is returned to the land as a fertiliser and soil conditioner. The avoided cost of fertiliser and the improved soil condition dramatically reduces the cost of production.
Mr McLaughlin said: "Recycling the N, P and K and remaining dry matter back onto the land improves productivity, land quality and land values. This process is already used for land reclamation.
"But to unlock this value we need to take a step back so we see the wood, not the trees."
Current Government agricultural policy aims to deliver 'sustainable intensification', but land use intensity has decreased over the last 20 years because of a lack of profitability in farming.
Mr McLaughlin added: "On-farm biogas production helps deal with the profitability issue and it helps the Government meet its renewable and environmental obligations.
"The Government should be looking at the costs, efficiencies and potential revenue streams in the whole energy production cycle and using that to inform much more challenging biogas targets.
"It seems to me the whole food versus energy debate is pointless. Food is just another form of energy, and the area given over to energy crops will never be massive – after 10 years of subsidies in Germany, it's still only 3 per cent.
"And do we really want to have land being underused? I don't think so."
DEFRA strategy for AD aims to produce between 3 and 5TWhrs a year from biogas in the UK.
EnviTec Biogas UK plans, builds and services anaerobic digestion biogas plants on farms across the country.