Transforming heat energy from coal mines

The Gateshead Mine Water Scheme, currently the largest heat recovery project in the UK, is transforming heat energy from coal mines into a sustainable solution. GEA, a key project partner, has provided two high-performance 3 MW heat pumps. These innovative pumps harness the energy from naturally heated mine water to meet the heat demands of buildings connected to the district heating network. By expanding the existing municipal heating network, Gateshead will benefit from an additional heat capacity of twelve GWh per year.

A Model for the Future: Gateshead, situated in the Northeast of England near Newcastle, is committed to achieving zero carbon emissions by 2030. Both Gateshead Council and Gateshead Energy Company (GEC), the operator of the Gateshead District Energy Network (DEN), view the mine water heat extraction system as a crucial component of their zero-carbon heat strategy. The primary objectives are to provide affordable heat energy for all residents and to complement the existing combined heat and power (CHP) system with a lower carbon footprint.

Positive Reception from Stakeholders: Councillor Martin Gannon, leader of Gateshead Council, expresses his excitement about the project's success, stating, "Gateshead's transformation is truly remarkable. Once leaders in the industrial revolution, we are now at the forefront of the clean energy revolution. Through our partnership, we utilise the naturally heated mine water to generate valuable, low carbon energy. We take immense pride in delivering the UK's largest mine water project successfully."

Richard Bond, director of innovation and engagement at the Coal Authority, commends Gateshead Council's forward-thinking approach, stating, "It's fantastic to witness local authorities like Gateshead Council utilising warm mine water to provide low carbon heating for buildings. The mine water in Gateshead serves as a low-carbon, secure, UK-owned heat source, offering a viable option for other coalfield communities. We are thrilled to have supported the realisation of this project."

From "Black Gold" to "Warm Gold": In the past, Gateshead's coal mines provided the region with valuable coal, serving both blast furnaces and heating homes. With the closure of the mines in the 1960s, the tunnels filled with water, which has now become a source of energy for the heat pumps. Once again, Gateshead's underground resources are playing a vital role in heating homes and industries. However, this time, the process is environmentally friendly, significantly reducing CO2 and NOx emissions.

The Extraction Process: The mine water is pumped from a depth of 150 meters to the ground level plantroom, where GEA's 3 MW ammonia heat pumps extract the energy from the mine water, which is at a temperature of 15 degrees Celsius. These heat pumps elevate the extracted energy's temperature, providing hot water at 80 degrees Celsius to residences and buildings in Gateshead. After the heat extraction, the water is returned to the mine at a temperature of eight degrees Celsius.

Optimised Performance and Renewable Power: To optimise the heat pump system's performance, a two-stage compression cycle with screw compressors is employed. Groundwater is filtered and circulated through titanium plate and frame heat exchangers. The choice of titanium for the evaporator plates matches the groundwater's quality. Additionally, the project incorporates solar parks located near the minewater boreholes and heat pump. These solar parks contribute to the power required to run the heat pumps, generating three units of renewable heat for every one unit of power used. GEC imports power from the grid, which is gradually decarbonising and expected to achieve zero carbon status by the mid-2030s. During sunny days, surplus power from the solar parks enables GEC to produce 100% zero carbon heat.

GEA's Commitment to Efficiency: Ammonia was selected as the natural refrigerant for this application due to its superior efficiency and absence of global warming potential. In the conditions present in Gateshead, ammonia heat pumps outperform F-gas solutions (HFC/HFO) by 10 to 20 percent in terms of efficiency.

GEA's Extensive Experience and Future Outlook: With a proven track record in heat pumps and district heating projects, GEA has previously implemented innovative solutions in the UK, such as extracting heat from London Underground ventilation air for a high-rise building in Islington. John Burden, Director of Project Sales Heating & Refrigeration Solutions at GEA UK, anticipates an increase in ambitious district heating projects in the UK, in line with the government's targets for significant expansion.