The Theoretical versus Practical Potential of Existing and Emerging Wastewater Heat Recovery Technologies

The UK heating sector must be completely decarbonized by 2050. The deployment of low carbon heat is thus an urgent policy and research priority. Multi-vector energy systems will be critical in this effort, and there is considerable potential for efficiency gains through better coordination between heat and water utilities. Urban wastewater contains a large amount of thermal energy that can be recovered and utilized to improve the performance of heat pumps. This is a potentially economical means of replacing fossil fuels with low carbon heat that reduces greenhouse gas emissions. According to a 2013 study, London needed 66 TWh/year for its heating needs in 2010, and there is 50 TWh/year available from existing secondary heat sources in and around London. Of this, an estimated 232 GWh/year could come from sewer mining. In last decade, many cities around the world have successfully implemented wastewater thermal energy recovery. In this paper we will explore the existing wastewater heat recovery systems operating around the world, their performance and viability