BY 2025 the Scottish government is aiming for 70% of all waste to be recycled, with only 5% going to landfill1, which could provide an opportunity for farmers looking to get involved in anaerobic digestion schemes.

There are already over 50 AD plants operating in Scotland, generating renewable energy from various feedstocks. With increased pressure from the government to meet recycling targets, and food waste currently being under-utilised as a feedstock, this figure is likely to grow, and quickly, according to Chris Negus, business development manager at Privilege Finance.

“According to ADBA, the industry body for the sector, AD plants in Scotland currently have the capacity to process 595,138 tonnes of agricultural waste per year," said Mr Negus. "In addition to this, there are Scottish digesters operating on sewage sludge, agricultural, industrial, domestic and commercial wastes."

The popularity of on-farm AD can partly be attributed to the environmental benefits associated with using agricultural waste, such as cattle slurry, as a feedstock, explained Mr Negus: “The AD process is less odorous than storing waste in slurry pits, and there can be benefits associated with water quality, when digestates are injected into the soil, reducing leaching risk. The use of the nitrogen-rich digestate that results from the AD process as a natural fertiliser also has significant cost savings compared to artificial fertilisers."

However, there is a growing opportunity for farmers to feed their digesters 'alternative wastes': “From 2021, Scottish landfill operators will be banned from accepting Biodegradable Municipal Waste (BMW) for disposal at landfill," he noted.

BMW includes any waste from households which is biodegradable, such as food, garden waste, paper and cardboard, but also extends to biodegradable wastes from the hospitality and retail sectors.

“This waste could be utilised within existing digestion systems, or used to supplement on-farm feedstocks, in ‘community’ AD plants – especially those located close to urban areas," said Mr Russell. “Farmers who may not have the capital to invest in AD outright could consider getting involved with a community scheme.”

As many livestock farmers are already painfully aware, by-products from whisky production, such as pot ale, can also be used to produce biogas through the AD process: “There are several distilleries in Scotland with anaerobic digesters on-site, however there is still potential for more. Zero Waste Scotland has calculated that Scottish distilleries produce a total of 1.6 billion litres of pot ale per year, which could provide a significant resource if the waste can be used for energy production."