Here are some frequently asked questions and answers to hopefully address any queries you may have. If we’ve missed anything or you have questions about something specific please don’t hesitate to get in touch. We also have information about geothermal energy and our project available in our about section.
What about water supply?
Water will be needed to set up the system, but the wells are totally encased with steel to a depth of 4km. This means that the water will circulate in a closed loop and will have no impact on local aquifers or present any risk of flooding at the surface. Any water released from the wells during maintenance or normal running will be contained in lagoons and treated.
Radon and background radiation is naturally produced by the granites and clays of Cornwall. The chemical composition of the water and all waste streams will be monitored and dealt with throughout the drilling of the wells. During operation, all water will circulate in a closed circuit so there will be no risk to the water table.
Is geothermal electricity expensive?
Geothermal costs are largely up front: drilling is expensive, and not every well will work. In countries with an established industry, conventional geothermal plants are cost competitive already. BEIS own figures show that on a levelised cost basis, geothermal electricity from the lower temperature resources we have in the UK would be about the same price as onshore wind electricity, and cheaper than biomass. If the heat can be used, it is cheaper still, and the technology is still at a phase where substantial cost improvements are expected.
Will it cool the Earth?
No. The heat extracted from the rock is a minute fraction of the vast heat available in the Earth’s crust. The design life of the plant is about 30 years, and after it has closed the heat in the rock will recover, possibly allowing the well to be reused after some decades.
Will drilling the rock cause problems at the surface?
Creating a geothermal heat exchanger is not the same as fracturing the rock to extract shale gas. Our purpose is to create a supply of renewable energy rather than release fossil fuels for burning. We will be working with natural fractures in the rock, and as the whole development will be enclosed in steel casing to ~4km, water table contamination is not an issue. We have no plans to use proppants or associated viscous chemical fluids to keep the circulation open.
- There are two companies developing deep geothermal resources in Cornwall; Geothermal Engineering Ltd (GEL) and Eden Geothermal Ltd (EGL). GEL has drilled two deep wells from its United Downs site near Redruth, Eden Geothermal will be drilling a well from the Eden Project site in 2020.
- These are renewable energy projects and do not involve fracking. They are not covered under the same regulatory framework as shale gas exploration projects and are not subject to the same limits on induced seismicity. Instead, they are regulated by the Local Authority and are monitored and managed using protocols based on a combination of magnitude and measured surface ground vibration, which has been used to control and monitor mining and quarrying activity in the county for many years.
- Small natural earthquakes happen in Cornwall all the time. GEL has installed a network of seismometers and has been monitoring since May 2018. In that time more than 20 natural events have been detected, with magnitudes ranging from 0.8 to 2.3. The most recent was on the 7th August 2019 near Helston, which reached 2.2 on the Richter scale. No damage was reported.
- GEL has successfully drilled two deep geothermal wells at United Downs with no induced seismic event of any kind.
Where is the plant going to be?
It will be near the main entrance gate to the Eden Project. This offers good access to main roads and will not disrupt access to Eden for visitors.
What is the site currently used for?
It is a field on a former landfill site. There is some woodland in the field which will be retained as the site is developed.
Will visitors be able to see what’s going on?
As part of the first phase of construction, we will build a viewing area so visitors can see the drilling taking place.
How long will drilling take?
It will take around five months to drill one well for the first phase.
Where is the drilling rig coming from? Will it be the same one used at United Downs?
We don’t know yet. The project is subject to EU procurement rules so the drilling rig will be sourced in accordance with these.
How loud is the drilling and will the rig operate 24 hours a day?
The drilling noise will be no more than 45db at 200m. This is equivalent to the noise of a fridge or light traffic and quieter than conversational speech (source: https://www.noisehelp.com/noise-level-chart.html). The drilling will take place 24 hours a day and, for safety reasons, the site will be lit at night.
How will the drilling rig be transported?
The rig is transported in pieces in a series of shipping containers. We will stagger the arrival of these containers so there won’t be more than nine or ten lorries delivering per day.
Beyond heating the Biomes, what else will heat from the plant be used for?
We plan to move Eden’s nursery from its current home near Pentewan to the main Eden site and use heat from the geothermal plant to heat the greenhouses. In the future, we will explore other opportunities to make use of the heat.
Is there any risk of damage to neighbouring property?
While we can’t say there is no risk, we are confident that the risk of seismic events causing damage is minimal. We are drilling into hard rock and exploiting natural fissures both of which represent a minimal risk of seismicity.
How long will the plant be there?
The project has a 40-year lifespan.
How many jobs will be created?
We anticipate that the construction phase will create 11 skilled jobs.
How long will the plant take to become carbon neutral?
We have calculated that four months of generating electricity following phase two of our geothermal project will be enough to compensate for the carbon emissions of drilling two wells.