Geothermal energy at TWI

TWI has been involved in several projects to help exploit and progress the use of geothermal energy by industry. Geothermal energy comes from the original formation of the Earth and the radioactive decay of materials. This energy is stored in the Earth and determines the temperature of matter, with the difference in temperature between the planet’s core and the surface driving a continuous conduction of thermal energy from the centre to the exterior. The temperatures at the core-mantle boundary in the Earth can reach over 4000°C and such high temperatures causes some of the rock to melt and the mantle to behave plastically with portions of the mantle convecting upwards as it is lighter than the surrounding rock. In addition, rock and water is heated in the Earth’s crust up to temperatures of around 370°C.

Sourcing geothermal energy

The geothermal resources within the Earth are theoretically more than enough to supply the energy needs of the entire planet, but only a small amount of this potential can currently be profitably exploited. Drilling and exploration of the deepest resources is very expensive, meaning that most geothermal energy is sourced from more accessible areas. This may change with improved technology improves, shifting energy prices and increased subsidies. However, there seems to be improvements in this area as the cost of generating geothermal power has dropped by 25% in the past two decades.

Where geothermal energy can be accessed, primarily for electricity generation, it has been found to be cost-effective, reliable, sustainable, and environmentally friendly. And, as technological advances open up the range of viable resources, there has been an increase in the applications of geothermal energy in areas such as home heating.

Environmental factors

The environmental implications of geothermal energy are far less than those associated with the use of fossil fuels. Despite geothermal wells releasing greenhouse gases from deep within the Earth, these emissions are far lower per energy unit than those from fossil fuels.

Geothermal energy challenges

While the future looks bright for geothermal energy, it is not without its problems. While these include the previously-mentioned concerns over cost and accessibility, the process itself also provides challenges related to the corrosion of metallic materials, wear, scaling and fouling, drilling, heat exchange, sludge treatment, waste and mineral extraction and efficiency.

TWI expertise and geothermal energy

Many of the challenges associated with geothermal energy exploitation relate to the aggressive environments associated with the extraction of geothermal energy. However, there are clear parallels with other industries in which TWI has a long history of expertise. These include petro-chemical plants, waste to energy and biomass, oil and gas exploration and production, gas turbine blading and conventional steam plants.

TWI’s experience and knowledge in coatings, material properties and performance, plant management, and joining technologies provide a unique gateway into geothermal work. For example, our experience with wear-resistant materials can aid drilling for geothermal plants. Coupled with our experience of structural integrity and integrity management as well as monitoring and inspection, these areas of expertise are already proving influential in a number of geothermal projects.

These projects include:

S4CE (Science for Clean Energy) - Implementing innovative technologies to monitor, manage and mitigate environmental risks

Geo-Coat - High performance erosion and corrosion resistant coatings

GeoSmart – storing heat energy to cost-effectively respond to network demands

GeoDrill - developing holistic drilling technologies that have the potential to reduce the cost of drilling to large depths and at high temperatures

With a proven track record of delivering both technical and commercial value, TWI is able to offer support and research across our worldwide network to develop solutions for the future of geothermal energy use.

Chris Punshon Industry Group Manager Power, Equipment and Infrastructure

Dr Chris Punshon joined TWI in 1983 as a project leader, following graduation with an honours degree from Sheffield University in Metallurgy BMet (hons), after a brief period post-graduation in 1982-83 working again as a heavy goods vehicle fitter and arable/livestock farming.

He has conducted a significant number of large and varied research programmes mainly focused on the power sector as well as oil and gas and marine industries, examining the relationships between materials, properties and performance in a wide range of materials and environments. For several years, he was responsible for the development of advanced joining process technologies for pipelines and pressure plant, seeing development from grass roots R&D to commercialisation, code approval and industrial exploitation.

His various roles within TWI since involved defining a renewed business strategy focusing on TWI key strengths and the emerging opportunities in the nuclear fusion, fission and renewable energy sectors, including offshore wind, solar PV, hydro, tidal stream and feeding a childhood passion for geothermal energy.

Lately, in 2017, following a re-structuring of the business development team, Chris was made responsible for the industry group covering power, materials, equipment and infrastructure with a responsibility for an annual R&D budget of over £15m.

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