The data presented in this paper originates from a CHP database maintained by AEA on behalf of DECC. Data relating to the overwhelming majority of CHP electrical capacity (over 99 per cent of total capacity) is received annually from the Combined Heat and Power Quality Assurance (CHPQA) programme, the Iron and Steel Statistics Bureau (ISSB) and from Ofgem’s Renewable Obligations Certificates (ROCs) returns. A small number of anaerobic digestion sites, obtained via a targeted survey, were added in 2010. The 2011 data also includes small schemes reported by suppliers but not registered under CHPQA. Data from CHP schemes not covered by the above are extrapolated from historic data.