Southampton
The centre of Southampton is located above a large hot water aquifer that provides geothermal power to some of the city's buildings. This energy is processed at a plant in the West Quay region in Southampton city centre, the only geothermal power station in the UK. The plant provides private electricity for the Port of Southampton and hot water to the Southampton District Energy Scheme used by many buildings including the WestQuay shopping centre. In a 2006 survey of carbon emissions in major UK cities conducted by British Gas, Southampton was ranked as being one of the lowest carbon emitting cities in the United Kingdom.

Q: What utility company sponsored a carbon emissions survey in 2006?
British Gas