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Information from the City of Southampton


Southampton has led the way in the development of the first geothermal energy and combined heat & power (CHP) district heating and chilling scheme in the UK. In 1996 the scheme celebrated its tenth anniversary. This brochure looks at the history of the innovative scheme, its present operation and the prospects for future development.


District heating is. cost-effective, environmentally acceptable, flexible and locally-based Geothermal energy is. non-polluting

District Chilling - system chilled water for air conditioning is a feature of Southamptons five-star De Vere Grand Harbour Hotel - connected in 1994. The chilling system circulates cooled water from the heat station through additional insulated mains which serve the hotel at West Quay. Waste heat from CHP generation is utilised by the absorption heat pump technology - in the winter, with the geothermal well; in the summer, to supply the district chilling system. A three fold increase of the chilling system is already underway to serve major new developments at West Quay. An innovative ice storage system will be added to meet peak loads from this development. The ice store will be filled with ice at night using electricity from CHP and cooling drawn off during the day.

Absorption heat pump effects energy transfer from a low temperature heat source to a higher temperature heat system (the district heating system) by the absorption process. This process can also be used during the summer to produce chilled water.


From the scheme launched in 1986, serving an initial core of consumers from the geothermal well, has grown a thriving and expanding £4 million multi-source heating and chilling system.

More than 20 major consumers in the city centre are now served by the district heating scheme. They include the Civic Centre, four hotels, the Royal South Hants Hospital, Southampton Institute of Higher Education and an ASDA (formerly Gateway) superstore. The store became the first commercial user when it signed up for the winter of 1987-88.

Current Statistics

After ten years of operation, the district scheme. delivers more than 30,000 MWh of heat each year alongside 4,000 MWh of electricity sold from the generating plant plus 1,200 MWh of power providing chilled water on tap and serves 20 major consumers in Southampton city centre

Circulating water is pumped around the city. through 11 km of insulated service pipes within a 2 km radius of the heat station with just 0.5°C/km in temperature loss offers substantial capital and operating cost saving to all consumers

Hot brine from the geothermal well today provides only 18% of the total district heating mix. Fuel oil (10%) and natural gas (70%) account for the remainder.

Southamptons well is more than a mile deep. The temperature of the water is 76°C at its source and two degrees less by the time it reaches the surface.

The water rises naturally in the well to within 100 metres of the surface. It is then pumped to the heat station. The hot brine is passed through a heat exchanger, working in conjunction with an absorption heat pump. The heat exchanger transfers the heat to clean water. The cooled brine, at about 28°C, runs out to the sea.

The power

Power for the downhole circulation pumps and plant is generated at the heat station by CHP. The heat from the CHP generators is fed into the district heating scheme. Surplus power is sold to the National Grid.

The station

At the heat station, heat transfers from the brine to the hot waterheat distribution system.

During periods of exceptionally high demand, extra heat can be provided by back-up boilers.

Combined Heat and Power (CHP)

Information from the City of Southampton http://www.southampton.gov.uk/environment/energy/default.asp

CHP energy means. reductions in CO2 emissions and the generation of heat and electricity

The ability of CHP to make electricity from conventional fuels and distribute the otherwise wasted heat adds considerable flexibility to energy planning. The promotion of CHP systems in the public sector is now very much in vogue. Southamptons successful and long-established operation is held up as an example to follow. Heat Distribution System - A closed loop of high-tech pipes distributes heat from all Southamptons energy sources around the city centre. For each user, a pair of pipes, with isolating valves and a heat meter, replace a conventional boiler. This amounts to a highly significant saving in space for customers. At ASDAs Southampton store, it is the difference between a modestly-sized cupboard and a boiler room of substantial proportions.