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Abandoned coal mine geothermal for future wide scale heat networks
Fuel 189 (2017) 445
Contents lists available at ScienceDirect
Fuel journal homepage: www.elsevier.com/locate/fuel
Letter to the editor Abandoned coal mine geothermal for future wide scale heat networks
18th December 2015 marked the end of the deep coal mining in the UK, with the last shift at the Kellingley Colliery. Centuries of deep mining across the UK, from Scotland, Durham, Yorkshire, Nottinghamshire and South Wales have left vast networks of flooded underground workings. With an agenda of low carbon supplies being actively investigated across the UK, one option in the renewable energy mix is the use of low enthalpy heat, using open loop ground source technology to recover heat from abandoned flooded coal mines to form wide scale heat networks. Recent assessment of this potential energy has been carried out in the South Wales Coalfield, with an average temperature of 13.35 °C, proving suitability for low enthalpy heat recovery and a significant renewable resource. Mine water systems make use of the permeability in previously mined areas where coal was previously removed. Mine workings and the remnant tunnels provide storage and pathways for the flow of underground water. The heat energy stored within this water is enhanced in deep mining systems and can be extracted using industrial ground source heat pumps. The first abandoned coal mine water power station opened at Heerlen in the Netherlands in 2008. It currently uses 32 °C water extracted from underground coal workings through boreholes in the Dutch coal mining heartland. This scheme is now used to heat three hundred homes and businesses, with an estimated 55% reduction in CO2 emission compared to conventional water heating systems. One current programme currently taking place in the UK to assess the potential for use of abandoned coal mine geothermal from the Caerau and Coegnant Collieries in the upper Llynfi Valley. This is being investigated to pump 10–14 °C and transport it through a network of pipes to residential properties to heat 1000 homes. Here the heat will be extracted and passed through a heat
http://dx.doi.org/10.1016/j.fuel.2016.10.115 0016-2361/Ó 2016 Elsevier Ltd. All rights reserved.
pump, which will then provide heat for the property using existing radiator systems. In South Wales region approximately threethousand litres of water is being drained or pumped from old mine workings per second. Using discharge and temperature data it is estimates that this is 72 MW of potential heating energy. This form of geothermal heating will also be used to heat stored in the flooded underground coal mine workings at the Cape Breton mine, which once supplied most Canadas coal. As well as providing a new form of sustainable energy for the local communities, it will also minimise the need for constant monitoring of abandoned coal mines. This can be necessary in some regions to avoid remaining coal catching fire. A classic example of a burning Colliery is that of Centralia in Pennsylvania, which has been burning since 1962 forcing residents out of the community. The development of wide scale heat networks offers a potential energy to replace traditional coal-fired power stations, which are due to be completely phased out by 2025. Initial investigations are being used to test for the technical and financial feasibility of utilising this energy resource to provide affordable heat for homes and industry. By 2050 the aim could be to use such networks to warm up to 40% of UK buildings. These exciting new projects show that there is significant potential to use abandoned mine waters as a clean source of energy for heating. This can provide energy security, reduction in carbon emissions and reducing reliance on traditional fossil fuels. Dr. Daniel J. Thomas C.Sci., C.Eng., FBCS College of Engineering, Swansea University, Bay Campus, Swansea SA1 8QQ, United Kingdom E-mail address: [email protected] Available online 3 November 2016
Contents lists available at ScienceDirect
Fuel journal homepage: www.elsevier.com/locate/fuel
Letter to the editor Abandoned coal mine geothermal for future wide scale heat networks
18th December 2015 marked the end of the deep coal mining in the UK, with the last shift at the Kellingley Colliery. Centuries of deep mining across the UK, from Scotland, Durham, Yorkshire, Nottinghamshire and South Wales have left vast networks of flooded underground workings. With an agenda of low carbon supplies being actively investigated across the UK, one option in the renewable energy mix is the use of low enthalpy heat, using open loop ground source technology to recover heat from abandoned flooded coal mines to form wide scale heat networks. Recent assessment of this potential energy has been carried out in the South Wales Coalfield, with an average temperature of 13.35 °C, proving suitability for low enthalpy heat recovery and a significant renewable resource. Mine water systems make use of the permeability in previously mined areas where coal was previously removed. Mine workings and the remnant tunnels provide storage and pathways for the flow of underground water. The heat energy stored within this water is enhanced in deep mining systems and can be extracted using industrial ground source heat pumps. The first abandoned coal mine water power station opened at Heerlen in the Netherlands in 2008. It currently uses 32 °C water extracted from underground coal workings through boreholes in the Dutch coal mining heartland. This scheme is now used to heat three hundred homes and businesses, with an estimated 55% reduction in CO2 emission compared to conventional water heating systems. One current programme currently taking place in the UK to assess the potential for use of abandoned coal mine geothermal from the Caerau and Coegnant Collieries in the upper Llynfi Valley. This is being investigated to pump 10–14 °C and transport it through a network of pipes to residential properties to heat 1000 homes. Here the heat will be extracted and passed through a heat
http://dx.doi.org/10.1016/j.fuel.2016.10.115 0016-2361/Ó 2016 Elsevier Ltd. All rights reserved.
pump, which will then provide heat for the property using existing radiator systems. In South Wales region approximately threethousand litres of water is being drained or pumped from old mine workings per second. Using discharge and temperature data it is estimates that this is 72 MW of potential heating energy. This form of geothermal heating will also be used to heat stored in the flooded underground coal mine workings at the Cape Breton mine, which once supplied most Canadas coal. As well as providing a new form of sustainable energy for the local communities, it will also minimise the need for constant monitoring of abandoned coal mines. This can be necessary in some regions to avoid remaining coal catching fire. A classic example of a burning Colliery is that of Centralia in Pennsylvania, which has been burning since 1962 forcing residents out of the community. The development of wide scale heat networks offers a potential energy to replace traditional coal-fired power stations, which are due to be completely phased out by 2025. Initial investigations are being used to test for the technical and financial feasibility of utilising this energy resource to provide affordable heat for homes and industry. By 2050 the aim could be to use such networks to warm up to 40% of UK buildings. These exciting new projects show that there is significant potential to use abandoned mine waters as a clean source of energy for heating. This can provide energy security, reduction in carbon emissions and reducing reliance on traditional fossil fuels. Dr. Daniel J. Thomas C.Sci., C.Eng., FBCS College of Engineering, Swansea University, Bay Campus, Swansea SA1 8QQ, United Kingdom E-mail address: [email protected] Available online 3 November 2016