The UK saw 23 biomethane-to-grid connections in 2015, making it the fastest growing market in the world for the technology. The new connections bring the total number of installed gas-to-grid plants in the UK to 50, almost doubling the figure at the end of 2014. Biomethane-to-grid is the process whereby renewable gas is injected into the UK’s gas grid, giving a flexible and efficient source of sustainable energy made from organic material including sewage sludge and food waste. Severn Trent’s Minworth wastewater treatment works (WwTW), Northumbrian Water’s Howden WwTW and Wessex Water’s Avonmouth WwTW are among the wastewater treatment sites to have made successful connections. By mid-2016, when all completed projects are at full capacity, it is expected that there will be around 120 million therms per annum going into to grid, with annual green gas production reaching 3.5 TWh per year. This injection will replace 240,000 tonnes of natural gas that would otherwise have been imported into the country. Biomethane is also increasingly being used as a fuel for transport, known as Bio-CNG. Wessex Water’s subsidiary GenECO has used the gas to fuel vehicles and is in talks with bus companies in Bristol about supplying them with the fuel.