Renewable Energy

The term “energy mix” refers to the combination of the various primary energy sources used to meet energy needs in a given geographic region.  The UK’s sources of power should ensure energy security, economic stability, maintenance of public health, protection of the environment, minimise carbon emissions and contribution to climate change.

The energy mix includes fossil fuels (oil, natural gas and coal), nuclear energy, non-renewable waste and the many sources of renewable energy (wood, biofuel, hydro, wind, solar, biogas, renewable waste heat, from heat pumps, and geothermal).  These primary energy sources are used for generating power, providing fuel for transportation and heating and cooling residential and industrial buildings.

For each region or country, the composition of the energy mix depends on:

• The availability of usable resources domestically or the possibility of importing them.
• The extent and type of energy needs to be met.
• Policy choices determined by historical, economic, social, demographic, environmental and geopolitical factors.

These differences can be appreciated by taking a look at the production and consumption figures for individual countries; “gridwatch” provide a live data feed for energy demand and the contributors to the UK’s energy mix (see the embedded website below).  At the moment there’s no geothermal power generated within the UK.

The UK’s renewable energy mix has become more diverse over time.  Renewable energy comes from sources that are not depleted when used but are replenished naturally.  They include wind, solar, hydro, tidal, wave and geothermal energy, and are generally used for power generation or heat production.

In 2013 renewable electricity sources contributed to only 14.9% of the power generated in the UK; by the second quarter of 2015 generation had exceeded 25% and surpassed coal generation for the first time.  In the second quarter of 2018, renewable electricity generation hit a record high of 31.7%,  On 21st April 2018 saw the UK completing its first coal free 24hrs since the start of the industrial revolution as coal dropped to an all-time low of only 1.6%.

The UK’s Future Energy Mix

The energy system of the future won’t look like today’s.  The scale of change over the next 10 to 20 years will be considerable and, while we don’t know exactly what this change will look like, we do know some of the areas that will be important.

One thing seems certain, consumers will play a key role in driving the change as their energy needs for warmth, light, power and, increasingly, mobility change.  The energy businesses of the future will provide those services cleanly, cheaply and efficiently by taking advantage of new energy technologies and digital enablers.

Decentralised energy is likely to play a key role in ensuring energy security at regional and local levels.  The term decentralised energy broadly refers to energy that is generated off the main grid, including micro-renewables, heating and cooling.  It can refer to energy from waste plants, combined heat and power, district heating and cooling, as well as biomass, solar energy and geothermal

One of the major benefits of decentralised energy is the move away from large power stations to localised production.  That means avoiding the wasted heat in power stations and instead using it locally, and avoiding having to produce the electricity lost in transmission because we have to send it so far.  According to Innovate UK, we waste about half of our energy in the UK.

With the rise of decentralised energy, local producer-consumers or ‘prosumers’ (a consumer who becomes involved with designing or customising products for their own needs) will need to flexibly manage the energy in the system, and technologies including energy storage, ways of adjusting usage better (demand-side response) and digital technologies using big data, analytics and cloud computing could help them do that.

As we strive towards a more sustainable future powered by renewable energy, successful geothermal projects offer decentralised energy and heating solutions that offer long term energy security for customers, as well as diversification within the energy mix.

These can be scaled according to the level of demand and specification for requirements; all they need is the correct geological conditions and some funding!

Geothermal Projects in the UK

For the UK, geothermal has had a role in furthering our understanding of power generation or heat production from both hot rocks and sedimentary aquifers.

We have used geothermal heat for centuries; one of the first examples of this form of energy is in the Roman city of Bath.  Not only were the hot springs a source of the famous public baths in the city, but they were used to warm local houses and to provide a constant supply of hot, clean water to the city’s population.

Geothermal projects can generate two forms of output – heat and electricity.

Both forms extract heat energy from the earth, accessing this requires wells from several hundred metres to several kilometres in depth.  Deep geothermal projects generally focus on energy production requiring a minimum of 150°C to generate sufficient power to make them economically viable. 

Hot water output on the other hand can be fed into a heat distribution system at a range of temperatures, and often forms a secondary output following energy production.

Driven by high oil prices in the 1970’s, the Hot Dry Rocks project was the first in the UK to investigate the potential for geothermal heat and power; this was undertaken in Cornish granites at Rosemanowes Quarry, near Penryn to a depth of 2km.  The results achieved a temperature of 79°C; quite far off the 150 – 200°C required for power generation; with more favourable oil pricing and a lack of funding, the project was abandoned with much of the research incentivising geothermal projects across Europe.

In 1987 a heat distribution system was developed in Southampton by extracting water at a temperature of 76°C from an aquifer at 1.8km depth.  This required infrastructure and a long term customer base to be viable, which Southampton City Council provided; the project is now run in partnership with Engie under Southampton Geothermal Heating Company Ltd.

The goal however is energy production, but this requires significantly higher temperatures in order to be viable.  

The UK doesn’t contain any active ‘hot spots’ as experienced by Iceland, Italy and Turkey who are the top producers in Europe. 

Not wishing to replicate the Kola Superdeep Borehole (the world’s deepest) which only reached temperatures of 180°C at 12,262m, means drilling deep into the granites of Cornwall and the Weardale.  Granite’s have raised levels of the radiogenic isotopes of potassium, uranium and thorium, whose radioactive decay leads to the accumulation of heat over geological timescales.  The granites become superheated when compared to sedimentary rock at the same depth; this in turn leads to an enhanced geothermal gradient which is the measurement of the temperature of the rocks as you move from the earth’s surface down through the crust.

In volcanic hotspots the geothermal gradient can be quite exceptional, in 2009 the IDDP-1 Krafla caldera well in Iceland intercepted rhyolite magma with a temperature of 900°C at a depth of only 2.1km.  This is an example of the extreme temperatures that can be encountered in the hotspots, although this particular well didn’t attain supercritical fluid pressures as the well was too shallow.

In 1986 the BGS published their book and map, “Geothermal Energy – The potential in the United Kingdom”.  This is a great resource which also addresses the presence of rare earth metals in geothermal fluids and possibility of their extraction for commercial gain.  This has become a particularly interesting sector with the high demand for rare earth metals in the production of electronical components, especially batteries and motors for electric vehicles and wind turbines.  A start-up “Cornish Lithium Ltd” is currently investigating potential in the region; both from mine water and future geothermal projects.

There was then a considerable break in active deep geothermal research in the UK, as projects were developed in more viable locations around the world.

World Geothermal

There are currently 366 geothermal power plants in operation across the world, with a total power generation of 14,600MW which when put into perspective constitutes only 72.5% of the UK’s total installed windfarm capacity of 20,128MW.  In 2018 the US had the greatest capacity with 3,639MW.

Depsite the relatively low production figures, the sector is continually developing, and in 2017 the Iceland Deep Drilling Project research well RN-15/IDDP-2, reached its target of supercritical conditions at a depth of 4.5 km; after only 6 days of heating, the measured bottom hole temperature was 426°C.

UK Geothermal Timeline

The Hot Dry Rocks campaign was never forgotten, and as geothermal projects have developed around the world there’s been more interest in the capability of parts of the UK to generate power.  This comes at a time where there’s an increased focus on sustainable energy and achieving amongst others, the 2020 target for cutting CO₂ emissions.  The Horizon 2020 and European Regional Development Fund have contributed significantly to the development of geothermal technologies and projects throughout Europe and in the UK.

In 2004 the Eastgate borehole was drilled to a depth of 0.9km into the Weardale granite producing temperatures of 46°C from brines contained within a hydrothermal vein system.  This indicated that at 1.8km, temperatures of 75-80ᵒC could be achieved, although no further wells were drilled.

In 2011 a 1.8km deep borehole attempting to intersect with the 90 Fathom Fault within the Weardale granite at Newcastle’s Science Central site.  This failed to generate sufficient heat to feed into a heat distribution network planned for the urban development; the rebranded Newcastle Helix reverted to a more conventionally powered hot and cold water distribution system.

In 2013 the Department of Energy & Climate Change (DECC) published their Deep Geothermal Review Study Final Report, this comprised an introductory document to the geothermal sector, the potential in the UK, as well as the processes by which a geothermal project might be brought to fruition.

Business Model

In 2014 I worked on a concept; recognising that whilst very much in the exploration and experimental phase, these are expensive projects that don’t have a guaranteed outcome; drilling and reservoir stimulation (where required) makes up a significant proportion of the total costs of both heat and power projects and almost all of the risk.

The viability of Deep Geothermal projects had increased in recent years as a result of a range of technical advances:

• Improved drilling technologies including the drilling of boreholes in hard rock to depths exceeding 5km, directional drilling techniques and improvements to pumps and valves.
• An enhanced oilfield supply chain associated with the recent US Shale gas boom has enabled a technology and knowledge transfer to the sector, including new seismic monitoring and stimulation methods creating highly conductive flow paths within the rock around boreholes.
• Improved understanding of geothermal reservoir development and operation following research by key European Institutions and funding programmes.
• Improved efficiency of energy conservation allowing heat recovery from lower temperature sources.
• New geological modelling allowing additional hot dry rock resources to be discovered.

However in 2014 no deep geothermal wells had been successfully drilled, with UK Engineering Geothermal Solutions (EGS) projects remaining in their conceptual stage as Operators tried to secure funding for new wells and commercial projects against a risk averse investment market and lowering energy prices.

We aimed to de-risk the deep drilling component by offering more than just a cheap borehole.

We developed an innovative business model incorporating the selection and acquisition of a drilling rig capable of drilling directional wells more than 5km down into the Cornish granites.  This could in turn service the burgeoning shale gas market in the UK and across Europe.  The Phase 1 Feasibility Study assessed Cornwall’s emerging geothermal sector including the requirements for drilling services and the impact that establishing such a capability would have on the region, by:

• Ensuring de-risked economically viable and environmentally sustainable geothermal wells.
• Enabling research & development projects linked to specialist drilling and Cornwall’s geothermal sector.
• Generating new skilled jobs whilst sustaining a wide ranging supply chain to support drilling operations.

With success in Cornwall, there was potential to utilise the technology on similar projects worldwide.

Following completion of the geothermal work scope, we could then employ the rig in the burgeoning shale gas sector.  This would optimise asset utilisation by accessing specialist oil field services focused on shale gas operations and reduce costs with lower mobilisation fees whilst we promoted Environmental, Social and Governance practice throughout the oil and gas supply chain.

However the shale gas sector (which uses very similar drilling and reservoir engineering techniques) was yet to establish itself as a viable industry in the UK.  Therefore the geothermal sector didn’t represent a significant enough market to make the purchase and maintenance of drilling equipment viable.  To date none of the 159 new blocks under 93 new oil and gas licences have been successfully drilled; we had a lucky escape.

Cornwall Today

Cornwall has been keen to explore geothermal projects for several years, both the Eden Project and GEL have put forward proposals for Deep Geothermal exploration with the added benefit of developing heat distribution networks and possible energy production.

The Eden Project’s proposal is to create an Engineered Geothermal System (EGS) comprising of two directionally drilled boreholes to a depth of between 4.5 and 5km into the granites of the Great Crosscourse.  Both wellbores will be capable of either production or injection ahead of reservoir characterisation tests. 

The first well will be completed and an engineered reservoir created.  Establishing an engineered reservoir is essentially fracking of the granite to create the pathways for water to travel from the injection well to the production well.  This enables the granite’s heat to be transferred to the injected water, however it does require a sufficiently fractured pathway to be created at considerable depth.  There would be no impact on shallower water supplies or other concerns associated with this type of stimulation / fracking

The second well will intersect the reservoir where it will optimise the performance and lifespan of the system.  The production interval of the second well will likely be spaced 600 – 700m from the first well; its location will be dependent on the results of the initial reservoir development.

The surface infrastructure would then deliver heat to the Eden Project’s domes as well as supply other initiatives such as large greenhouses.  Power generation will also be considered given the right conditions and flow rates experienced.

However it’s GEL that have been first to break ground.

At the end of 2018 GEL were the first to be drilling into Cornish granite.  With two wells planned, they’re intending to follow a more conventional plan and intersect a fracture zone which will provide them with a hot water reservoir from which to farm the heat.

A production well will intersect the Porthtowan fault at a depth of 4.5km.  A second shallower injection well will connect up with the same fault line at a depth of 2.5km.  Water will be injected into the fault at 2.5km and permeate down through the naturally fractured granite to feed the existing reservoir.  The deeper production well will then extract this super-heated water and bring it to the surface; utilising a heat exchanger this has the potential to feed a turbine and produce electricity.

By drilling the production well first, GEL will get an immediate understanding of the temperatures to be encountered as well as the flow of water at depth.  The shallower secondary well will then be completed to close the loop.  I suspect that if they don’t get sufficient heat for energy production, then they could decide to drop the injection well, therefore saving money.  

Costing in the region of £18 million, the project has three principle funding streams:

• The ERDF has provided £10.6m under its Priority Axis 4; “Supporting the Shift Towards a Low Carbon Economy in All Sectors”.
• Cornwall Council has provided £2.4m.
• Private investors have provided £5m.

GEL have employed the HAS INNOVA rig owned by Angers-Söhne; this was specially designed for deep geothermal projects.  It was mobilised in approximately 80 truckloads from Finland where it was working on the t1 Deep Heat project which completed drilling the OTN-III well at a depth of 6.4km in early 2018.  Over the summer the well was stimulated in order to create an engineered reservoir.  I understand that this reservoir will be tested and mapped out in order to design and drill the injection well at a later date.  There is an interesting blog by the SMU Geothermal Laboratory which has tracked the progress of the project.

Let’s hope that they achieve the target temperatures and flow rates, generating power and further interest in the Cornish granites!

Cornwall Tomorrow

The future of Deep Geothermal relies heavily on the success of GEL and their United Downs project.

If the project doesn’t meet its objectives, then it’s vital that all stakeholders are able to deal with and appropriately manage failure; it is an essential part of scientific development and understanding. 

Although only a small proportion of the overall funding originated from Cornwall Council it still constitutes £2.4m of public money that could have been reallocated in this economically deprived area where wages across the county are 23% lower than the national average; especially when success isn’t guaranteed and a significant proportion of the work is likely to have been sourced from outside of the county.

Part of the project’s demonstration of good Environmental, Social Governance will be to ensure that the region both benefits from the work undertaken and that a positive legacy is established.

As the technology and scientific understanding develops, this includes learning from the experiences of Shale Gas operators, as well as the large number of geothermal projects undertaken throughout the world and in a variety of geological and geothermal settings, then the risk of failure will decrease.

Learning from the experiences of GEL, will give the likes the Eden Project the opportunity to maximise the potential for success, as well as introduce cost savings, enhance safety, community engagement and other aspects of good Environmental, Social Governance expected of this burgeoning sector.

As we progress to a more sustainable future, using “AC” (alternating current) rigs hooked up to a national grid that’s powered by renewable energy would be an environmentally sustainable way to drill deep geothermal wells.  These often take in excess of 20 weeks to complete; alternatively that’s a lot of diesel consumed by generators operating 24/7. 

Removing the need to engineer reservoirs at significant depth will also

Stimulation of the OTN-III well was undertaken over 6 week period during which 18,000 cubic meters of drinking water were injected.

Enabling a social license to operate. 

Precedents have been set within the UK shale gas sector for an aversion to fracking by the general public. 

Complex planning procedures as well as significant restrictions on the levels of induced seismicity have made the exploration for shale gas unviable. 

Although for different end purposes, ensuring that the general public and stakeholders are able to differentiate between fracking for shale gas and fracking for geothermal.

The post fracking review also requires 5 to 7 months of anaylsis prior to the second well being drilled.  This adds tp extra mobilisation / demobisitli costs, pressure on local road netwrks, impact on the environment.

the need to employ fracking techniques will result in cost, confrontation and uncertainty.

Reducing the carbon footprint for mobilisations and demobilisations is also key, as transferring 80 trailer loads of equipment across Europe is not sustainable.  However the sector would require clear project pipelines in countries in order to secure rigs or justify building newer ones.  With the shale gas sector struggling across Europe, the desire for large directional drilling onshore rigs is significantly lower than it could be.

Heat productions relies on feeding into existing heat distribution networks.  Creating this infrastructure is expensive and relies on long term customers.  This was successful in the case of Southampton, but failed in Newcastle when the project failed to achieve its objectives.

Projects around the world will contribute to the success of Deep Geothermal in the UK.

Projects such as the t1 Deep Heat project in Finland act as good analogies from which to learn from; this project encountered a number of issues and delays during the drilling of the OTN-III well.