Geothermal energy is a renewable, clean energy source that performs well against other renewables.
We’re excited to see the UK’s first geothermal electricity plant switched on this month. The United Downs Deep Geothermal Power Project will be able to provide 10,000 homes with clean electricity through Octopus Energy.
It has taken more than two decades to bring the plant online, during which engineers had to drill the deepest on-shore well in the UK – three miles underneath the earth’s surface where it is hot enough to heat the water required to spin the turbines and generate the electricity.
Ground source heat pumps for domestic use work in a similar way, drawing heat from the earth to heat our homes, but they only go a few metres down whereas geothermal energy requires much greater depths to reach the +200°C.
The funding for the site has come from private investors – one of the first commercial funders for the plant is our patron Thrive Renewables who are proud of their contribution – and the EU (prior to Brexit). It has cost £50m to date (BBC).
The project will be difficult to duplicate, say The British Geological Survey but it is a ‘great step forward’. It all sounds like a lot of work. Geothermal Engineering Ltd (GEL) who drilled the site have another two sites in mind.
What are the benefits of geothermal energy?
One of the biggest benefits of geothermal energy is its stability (Enel). Unlike solar and wind power which fluctuate, geothermal energy is constant and reliable. The baseload is not affected by the weather or time of day.
Despite the initial expense, geothermal power plants can operate for a century. They have low maintenance costs and a high operating capacity. There is little impact on the local environment as they are silent and have a small footprint and the heat from the earth is expected to last for billions of years.
Geothermal energy is safer than nuclear energy, without the problem of radioactive waste disposal, and risk of meltdown (Interesting Engineering). If a suitable site can be found with a high sub-surface temperature (Gov UK) it may be viable. This is usually near tectonic plates, volcanic activity or geothermal gradients (deep, hot, permeable rock). They also need a water resource nearby. Nuclear plants can be built anywhere.
From a sustainability standpoint, geothermal power is preferable as it generates relatively few greenhouse gases when compared to fossil fuels. It can achieve close to zero emission status if it is designed with a closed loop system.
One side benefit of the United Downs geothermal plant is the production of lithium, widely used for lithium-ion batteries and essential for electric car battery production. The plant will initially produce enough lithium for 1,400 electric vehicles annually, but there are plans to ramp that up.
Globally, geothermal energy is getting attention from investors. The world’s need for power is increasing and we need to find sources of energy that are both clean and renewable. Geothermal power production is one of those options and it has a lot of benefits over other renewable energy sources but the cost is a barrier, as is the need for suitable sites and permissions to drill.
Here in the UK, more geothermal power plants would help us to decrease our dependency on other nations for the energy required to operate our businesses and homes. And it would be a renewable, clean and reliable energy source.