This document is an annex to the ‘Future of the subsurface’ report. It draws on a series of UK and international case studies to highlight current issues and potential solutions for subsurface space management.
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Overview
This document is an annex to the Future of the subsurface report completed by the Foresight team in the Government Office for Science. It has been informed by a literature review and stakeholder engagement, and draws on a series of UK and international case studies to highlight current issues and potential solutions for subsurface space management. The document structure is outlined below, along with key points from each section. Refer to the geothermal annex page for full details of the section summaries below.
Background
The review begins by introducing geothermal energy. Geothermal energy is energy in the form of heat that is stored below the Earth’s surface. It derives largely from within the Earth, though at shallow depths, heat is partially provided by solar radiation. The temperature of geothermal heat and extraction technology used varies by depth and geology. Near the surface, shallow geothermal heat is stored in the ground, aquifers, and in flooded coal mine workings. It can be extracted by ground source heat pumps and is suitable to be used for heating. Deep geothermal energy is extracted from depths greater than 500 metres, and it can be suitable for either direct-space heating or power generation depending on temperature and depth.
Current UK status
The review then introduces the current UK status, and some UK examples of geothermal applications. Geothermal heat provided 0.3% of annual heat demand in the UK in 2021, which included 43,700 ground source heat pumps, deep geothermal direct-use, and mine geothermal schemes. Geothermal heat is not regulated as a natural resource and whilst geothermal developments are regulated, the particular regulations governing them vary by the type of heat extraction technology used and in each devolved administration of the UK. Current examples of geothermal applications in the UK include a pilot scheme to provide geothermal heat as a utility, a scheme providing heat to homes from flooded mine workings in Gateshead, and the first geothermal power plant which is under development in Cornwall.
International examples
The review then considers some international examples. Outside the UK, the US, Indonesia, and the Philippines lead in geothermal energy development, whilst Sweden and the Netherlands have ambitious programmes for expanding geothermal use. France and Germany are also looking to expand their geothermal energy usage and have developed ambitious targets and strategies to increase its use. As France and Germany have similar geology to the UK, they are presented as potential examples to follow.
Challenges and opportunities
The review then highlights some challenges and opportunities related to geothermal energy production in the UK. There are significant benefits of geothermal energy compared to other forms. Geothermal energy is low carbon, and is available constantly and domestically, meaning it can contribute to Net Zero whilst also improving energy security. The most significant opportunity geothermal energy presents is decarbonising heating buildings, which accounts for around 17% of UK emissions through deploying geothermal heat schemes at scale. However, significant barriers to the effective deployment of geothermal schemes include complexity and gaps in regulation, high project costs, and a lack of accessible subsurface data.
Example systems interaction
The review ends by showing an example systems interaction. The availability and extraction of geothermal heat is affected by, and affects, many other parts of the subsurface system. External factors such as conditions at the surface can also have an effect. The review outlines one example interaction developed in the project in consultation with stakeholders, based around transport tunnels and heat.
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