David Charles Andrews has worked in the energy field for 40 years. His principal activities are in small-scale power generation with CHP, and he was a principal driver of the introduction of gas engine CHP into the UK in the 1980s. He has worked in the practical part of the Combined Heat and Power and Engine Generator industry and has contributed numerous articles and learned papers on the subject and its relevance to energy policy. He chairs the Claverton Energy Think Tank of energy experts and is a member of the District Heating and Cooling online network of experts. For two years he was an Invited Expert and Senior Advisor for Power Generation for the EUs JRC at Petten and produced numerous learned reports, which pointed out methodological errors in the then-current method of modelling CHP, which seriously undervalued its contribution. Over his career. David has written numerous reports and articles covering renewable energy, renewable power generation, district heat and integrating renewables with the power grid.