Expanding biogas on UK dairy farms: a question of scale

Expanding Anaerobic Digestion (AD) in the UK will not only depend upon finding appropriate economic structures to support on‐farm developments but also an appreciation of environmental issues such as less Greenhouse Gas (GHG) emissions; reduced use of artificial fertilisers; and better management of farm wastes. At the core of this paper is the Anaerobic Digestion Analytical Model (ADAM) that examines the economic and environmental impacts of integrating AD into UK farming systems. However, the average dairy farm in the UK is not of sufficient size to enable profitable biogas production. Indeed, farm size, as represented by FBS/FAS data used in ADAM, needs to be scaled by three to four times for a biogas enterprise to break‐even. To boost profitability, some farms may use additional energy (food and non food) crops as well as other high energy sources such as biodiesel residues etc. In some circumstances, possibilities may exist for neighbouring farmers to co‐operate and manage a biogas installation that processes manures and energy crops to increase the scale of an on‐farm plant. Despite issues of scale however, on‐farm AD plants do have the capacity to (i) reduce Carbon Dioxide equivalent (CO2e) emissions that a dairy farm produces; and (ii) the by‐product of digestate provides farms with greater nutrient availability for crops.