Wednesday, September 22, 2021
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Geothermal potential – Why hot rocks are cool

Images: Supplied

As we need more and more reliable clean energy, Dr Ryan Law says we must not ignore the untapped geothermal potential beneath our feet.

At the end of April 2021, the UK government reset its own climate goalposts and pledged to enshrine in law the most ambitious climate change targets in the world, committing to reducing greenhouse gas emissions by 78%.

However, as the UK commits to leading the way on systemic decarbonisation, this ambition is not currently matched by adequate sources of a renewable energy and heat.

Geothermal energy has the potential to significantly contribute to the country’s net-zero goals alongside, of course, a variety of other energy solutions – but currently, its potential as source of both heat and baseload electricity is not being taken advantage of.

It is highly dispatchable, renewable, and capable of sustaining projects for lifespans of over 50 years. With November’s COP26 calling the attention of the world to the UK’s climate action, the country cannot be seen to be wasting, undervaluing, or ignoring the natural resources that can accelerate its plans.

The UK is home to a number of locations suitable for deep geothermal energy drilling, as well as several hundred defunct oil and gas wells that could be modified and converted.

As well as electricity, geothermal energy can provide large quantities of renewable heat from underground to the surface. The heating of homes and district heating is a challenge for decarbonisation, but geothermal heat provides a viable zero-carbon alternative to gas.

Agriculture and other industries can benefit too; for example, the United Downs Deep Geothermal Power Plant in Cornwall is to deliver a rum distillery with zero-carbon heat and power.

Jobs and carbon savings

A recent report from engineering consultants Arup states that by delivering up to 12 deep geothermal projects per year over the next 30 years, the UK could host 360 plants that together would be able to generate between 200 and 400GWh of electricity per year, and up to 15,000GWh of heat.

Image: Supplied

The benefits of investing in geothermal energy are not restricted to renewable electricity and heat: it is estimated that enough projects would create 10,000 direct jobs and 25,000 indirect jobs, generating £1.5 billion ($2bn) of investment.

These jobs would clearly be concentrated in areas with promising geological conditions such as Northumberland, Durham, Cumbria. Newcastle upon Tyne, Staffordshire, and Cornwall – several of which are areas that the government has pledged to ‘level up’.

The development of 10 to 12 projects over the next five years in these areas would lead to 500 to 500GWh of heat per year, which would supply the equivalent of up to 50,000 homes with investment in the order of £10 million to £15 million ($13.9 – $20.9 million) for each project.

At the same time, the development of these types of projects would lead to a carbon savings of up to 80,000 – 100,000 tonnes, purely through the decarbonisation of district heating.

With or without the government

But growth in UK geothermal projects is expected to continue to proceed too slowly without intervention from the government, such as those that have been used in the Netherlands, Germany, and France to stimulate deep geothermal projects.

In the Netherlands, the number of deep geothermal projects increased from one to 18 over a decade, and now at least 21 exist. Presently, the Dutch government aims to deliver 10 new deep geothermal projects each year by 2025, then 20 per year by 2030, and 25 per year by 2050. This strategy will result in 700 projects over the next 30 years, and the UK has enough resources to deliver projects at a similar rate.

Assistance from the government should take the form of a dedicated deep Geothermal Development Incentive. A heat production incentive dedicated to deep geothermal projects could be structured in a way that it provides assurance to the geothermal market, while providing funding only for projects which successfully generate heat or electricity.

To control the cost of an incentive scheme, the government could limit the use of a Geothermal Development Incentive to the first 30 projects which meet application conditions.

At the same time, the government could review the planning permission requirements for projects and make some minor changes to the Contracts for Difference for geothermal power in the next auction round.

UK market development

Arup’s report into the potential for deep geothermal power in the UK identifies that setting the minima of 50MWe for geothermal projects would improve investor confidence and I agree with that.

If such improvements to the system were made, following an initial ramp-up, the UK could deliver 10 or more projects each year, with a production system consisting of surface heat exchanger with production and reinjection wells connected to the same aquifer.

This growth rate would be expected only to increase over time as markets develop and supply chains mature.

The UK government should be investing in the future of an energy resource that has yet to fulfil its potential

Indeed, once the UK’s geothermal market and sector expertise is developed, there is nothing to stop the country from exporting it and supporting the uptake of the energy resource around the world.

The UK has a long history of innovation in the field of deep geology, and investing in geothermal energy could lead to the UK becoming both a climate action leader and a specialist in the energy resources that lie beneath our feet.

British projects in Cornwall have already pioneered the co-production of lithium from geothermal brine, and other areas of the geothermal supply chain such as specialist equipment and component manufacturing, digital engineering and consulting, financial expertise, and deep geothermal training are fields in which the UK could lead.

The UK has experimented with, and benefitted from, geothermal heat for thousands of years, from the construction of the Roman thermae in Bath around 75AD to the first deep geothermal wells in Cornwall.

But as well as celebrating a rich heritage in ‘hot rocks’, the UK government should be investing in the future of an energy resource that has yet to fulfil its potential.

Decarbonisation is a mission of such scale and urgency that we cannot afford to leave such a rich resource unused.

About the author

Dr Ryan Law is Managing Director of Geothermal Engineering, a team of specialised geologists and engineers who have developed several projects, including the £30 million ($41.7 million) United Downs initiative in Cornwall.

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