Hill of Banchory geothermal energy project: feasibility report

Report of a study which explored the potential for a deep geothermal heat project at the Hill of Banchory, Aberdeenshire.

19. Next Steps

This project has strongly supported the hypothesis that the Hill of Fare granite could be successfully exploited to provide low-carbon renewable heat to augment and support expansion of the existing Hill of Banchory district heating network. The results are sufficiently encouraging that they justify seeking funding to sink one or more pilot boreholes and to expand geophysical prospecting around the Hill of Fare pluton. In parallel, further engagement with local landowners and with the public ought to be undertaken, so that if the results of the geoscientific work are favourable, the way will be clear to begin to develop specific plans to drill a production and reinjection borehole doublet system.

Accordingly, the next steps to take forward the Hill of Banchory Geothermal Project would be as follows. We assume that the next phase of the project would be predicated on the continuation of the current consortium, which would engage third parties with the relevant expertise to assist as necessary. We also expect that some of the consortium members would in time form the core of a 'Banchory Geothermal Energy Services Company' ( ESCO). We anticipate that Aberdeenshire Council would play an increased role as the project developed and a robust business plan was worked up.

The consortium members make clear that their ultimate objective is creating a geothermal borehole doublet at Hill of Fare that will supply low carbon, renewable heat to customers in Banchory. The steps above are designed to take the project to the point where a fully robust business case can be produced for this high profile project.

We note that an essential element in the development of a deep geothermal well at Banchory will be the presence of a suitable heat customer. An expansion of the heat network in Banchory offers the most obvious way to deliver this. This would facilitate the wider deployment of renewable heat and align with Scottish Government's targets on district heating. We expect Aberdeenshire Council to play an important role in this process, not least because they oversee several large individual heat customers in Banchory.'

We have made indicative estimates of timelines and budget required for each task (italics).

1. Procure funding and relevant permits (most notably from the Scottish Environmental Protection Agency and the local planning authority) to facilitate the actions at point 2.

We expect obtaining regulatory permission for the pilot drilling to take 3-6 months. There is nothing particularly unusual in the drilling being proposed, so this should be relatively straightforward. On this assumption, costs of £5-10K0 should cover administrative effort.

2. Drill, sample (using cuttings and spot coring), case, geophysically log and test-pump at least one (and ideally three) pilot boreholes completed to depths of 600m - 1000m (i.e. deep enough to extend below the weathering zone and largely below the zone of palaeoclimatic influence). Consider retaining the completed borehole(s) for future piezometric and micro-seismic monitoring.

Drilling each pilot hole should take around 3 months, including well pad preparation and site reinstatement. Preceding this, a procurement exercise to select a drilling company could take 2-4 months. Boreholes drilled into granite are relatively rare, but the 995 m deep borehole drilled into the Weardale granite in County Durham in 2004 cost £460K. Test pumping and other analysis could take up to 1 month, and cost (again to judge from Eastgate test-pumping in 2006) up to £50K per borehole, depending on the precise regime devised from the findings of the drilling and geophysical logging.

It should be noted that, following completion of the above works, the three boreholes would be retained for possible future re-use for monitoring of supra-reservoir water pressures, temperatures and micro-seismicity in the event the future production and reinjection boreholes are commissioned. Hence the investment in this phase of the work would create some reusable assets in addition to essential data.

3. In parallel, complete surface geophysical surveys (gravity, passive seismic etc.) should be carried out. On a longer timescale, work should be undertaken to improve our understanding of the natural fracture networks in the granites and their associated hydraulic conductivities. This would include LIDAR fracture surveys of the exposed granites in the Hill of Fare quarries.

The costs for a geophysical survey, the fracture network analysis, experiments of granite failure and coupled numerical simulations would be around £200K. Initial results could be generated within 6-12 months, with a fuller academic study extending into the medium term.

4. Develop a detailed plan and schedule for the drilling, logging, testing and commissioning of the permanent production and reinjection boreholes.

This would be carried out by the consortium members, assisted as necessary by specialist consultancy advice. Estimated cost £30-50K, timescale 6-12 months. The input from the consortium would perhaps be on a similar scale to the first phase of the project.

The following tasks would be carried out by consortium members, with the transition to an ESCO in mind.

5. Liaise with local landowners over the possibility of agreeing sites for production and reinjection boreholes and wayleaves for pipelines to take water to / from the existing Hill of Banchory energy centre.

6. Run further public engagement events locally, regionally and nationally, including opportunities for the public to experience drilling at first hand during (2) above.

7. Initiate the search for investment to allow the project to proceed.

These tasks are unlikely to require significant non-wage costs, but would involve extensive input of employee time for consortium members. We estimate these tasks will take 2-4 months, and will cost £50-75K.


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