Heat energy from the coal mine: "Gateshead Mine Water Scheme" is currently the largest project in the UK for heat recovery from mine water. GEA as project partner supplied 2 x 3 MW high performance heat pumps.
These heat pumps use the energy from naturally heated mine water to meet the heat demand of the buildings connected to the district heating network. The existing municipal heating network, which already supplies 18 public and private buildings and 350 households, will thus be expanded by an additional heat capacity of twelve GWh per year.
This is how heat is extracted from mine water
The water is pumped from a depth of 150 meters from the old mine to the ground level plantroom where the 2 x 3 MW ammonia heat pumps from GEA, extract the energy from the mine water (15 degrees Celsius). The heat pumps boost the temperature of the extracted energy and hot water (80 degrees Celsius) is then provided to homes and buildings in Gateshead. When the heat from the mine water has been extracted by the heat pumps, the water is returned to the mine at a temperature of eight degrees.
To optimize the performance of the heat pump system with the 2 x 3 MW heat pumps, a two-stage compression cycle with screw compressors is used. Groundwater is filtered and pumped through titanium plate and frame heat exchangers. Titanium was chosen for the evaporator plates to match the quality of the groundwater. On the heating side, several heat exchangers are connected in series to optimize the efficiency of the heat pump solution.
Solar parks are also part of the concept - which help to provide some of the power to run the heat pumps - these have been newly built on a field next to the minewater boreholes and heat pump. For every 1 unit of power used by the heat pump, 3 units of renewable heat are generated. GEC will import power from the grid to run the heat pumps... which is decarbonising year on year and should be zero carbon by the middle of next decade. On sunny days, when GEC has surplus power from the solar parks, this will provide green power to run the heat pumps, meaning that for certain periods, GEC can produce 100% zero carbon heat now.
GEA ammonia heat pumps offer optimum performance
Ammonia was chosen as the natural refrigerant for this application. It offers the best efficiency and has no global warming potential. Under the given conditions in Gateshead, ammonia heat pumps are 10 to 20 percent more efficient than F-gas solutions (HFC/HFO).
