Engineers in Stirling are getting ready to open the UK’s first low-carbon energy hub which uses waste water. Scottish Water aims to heat several public buildings, including a school, a leisure centre and a stadium, through a mixture of cutting-edge technologies, including heat pumps, at its sewage works at Forthside. Their £6 million scheme, which has financial backing from Stirling Council and the Scottish Government, was visited by First Minister Nicola Sturgeon yesterday ahead of its switch-on next month. The new energy hub consists of a conventional natural gas combined heat and power (CHP) engine, heat from a waste water heat pump system, thermal stores and back-up gas boilers for the district heating network. The CHP engine generates heat for the public buildings and electricity for the sewage plant and the waste water heat pumps. The heat from waste water technology, provided by SHARC Energy Systems, uses a heat recovery unit to separate liquid and solid waste, which is returned to the treatment process. A heat exchanger transfers the heat from the waste water to the clean water using a closed loop system. A heat pump increases the temperature of the water, which is then delivered to the district heat network. Electric heat pumps – essentially reverse fridges – are being developed on an industrial scale across the planet. In Clydebank, local authorities hope to use pumps to capitalise on the relative warmth of the local river to heat a new neighbourhood. Scotland has Europe’s worst record on renewable heat.