Anaerobic Digestion is a process that refers to the breakdown of organic matter in the absence of oxygen. Anaerobic Digesters use this process in order to collect the methane gas produced. The methane can be used for fuel in transport, injected into the mains gas system or combusted in a combined heat and power (CHP) unit to produce electricity and heat.
The CHP use is the focus of this publication. It provides an insight into the growth of the farm AD CHP sector and looks at the performance of AD plants over the past decade. While electricity forms the main source of income for CHP projects, the heat generated provides an important additional income.
Many on farm AD projects were driven by innovative farmers who identified an opportunity to integrate renewable energy into their farming operations. However, much of the early growth was funded on the back of beneficial tax relief schemes such as the Enterprise Investment Scheme (EIS), Venture Capital Trusts (VCT) and SEIS (Seed Enterprise Investment Scheme) before eligibility was withdrawn in 2015.
Our research shows the growth in the AD sector since 2008 (Figure 1). The introduction of the Feed-in-Tariff (FIT), and banded NIRO in Northern Ireland, and latterly the Renewable Heat Incentive (RHI) had a significant impact on the AD industry. They made the development of smaller and medium scale plants possible and opened up the sector to a new group of developers which includes farmers. The majority of growth in farm AD occurred in 2014 and 2015 following AD over 200kWth being made eligible for Non-Domestic RHI in December 2013.