The Committee on Climate Change go anaerobic...

Along with others from the Committee on Climate Change (CCC), I recently visited Crouchlands Farm, a 750 cattle dairy business in West Sussex. It’s home to Gwyn Jones, the NFU’s Vice President. We were there to tour the farm’s newly installed 1MW anaerobic digestion (AD) plant and to discuss GHG emissions reduction from farming with representatives of the National Farmers Union (NFU).

The visit followed the CCC’s 2010 progress report to Parliament. This report identified cost-effective opportunities to reduce methane emissions from livestock manures by increased installation of on-farm AD plants (approximately 0.6 MtCO2e in savings). At present methane emissions arising from manures account for 3 MtCO2e, or around 6.5% of total agricultural GHG emissions.

In the report, we’ve argued that new approaches will be required to encourage emissions reductions in the agricultural sector. Gwyn and NFU colleagues noted that for AD, planning, compliance and finance for smaller scale plants were significant barriers that needed addressing. However AD remains an attractive option to farmers due to the many win-wins it provides around resource recycling as well as fulfilling requirements from other regulation.

Faced with increased Nitrate Vulnerable Zone (NVZ) restrictions (requiring installation of expensive manure storage facilities), Gwyn opted to invest in a £2 million AD plant. The plant converts agricultural waste into renewable energy, solving his NVZ problem and providing an alternative source of farm income.

The plant consists of two digester towers, which are fed on a combination of slurry collected from the dairy farm as well as maize (produced at a local arable farm on poorer quality land) and grass silage, which together form an optimal feedstock mix.

The feedstocks are mixed in the towers on a 90-day cycle, producing a biogas which is then converted into electricity and sold directly into the National Grid. After the 90-day cycle, a nutrient-rich digestate is produced from the waste products, which is then separated into solids and liquids. The solid digestate is spread back to cropland (used to grow maize) and the liquid slurry to pasture land, providing a nutrient recycling system and saving the farm in fertiliser costs.

The plant will also pay its way - earning returns from the Renewables Obligation scheme as well as tariffs received from selling the electricity generated. Gwyn anticipates a payback for his investment in 4 to 5 years.

Trips like these help inform our work, which is to provide independent advice to Government on how to tackle climate change. The CCC will publish its ‘4th Budget report’ on 7th December, which will set out our advice on the 4th carbon budget – the budget specifies the level of GHGs that can be emitted from each sector during the period 2023-2027. It will include a chapter on agricultural emissions and abatement opportunities. To read more about the CCC’s work on agriculture click here to visit our website.

Kavita Srinivasan is a Senior Analyst at the CCC, looking at how Agricultural emissions reductions should form part of the Governments wider strategy for meeting carbon budgets. The Committee on Climate Change is an independent body that advises the Government on tackling and preparing for climate change: www.theccc.org.uk