The exploration of salt deposits and assessment for use as energy storage facilities involves both physical and non-invasive exploration of the resources. The environmental impact of such activities and monitoring of same are covered in the licence to explore awarded by DETI. Awardees of these licences must abide by the Guidelines for Holders of Prospecting Licences under the Mineral Development Act (Northern Ireland) 1969. Additionally an Environmental Impact statement will be made as part of the SPIRE project.
This part of the project will conduct a feasibility study into the viability of approximately 1 GWh of energy storage based on compressed air energy storage (CAES) technology. CAES works by storing a volume of compressed air in an underground cavern. The key features are that grid electricity is used to compress air, compressed air is stored in large impervious caverns, e.g. salt caverns at pressures of 45 to 70 bar, then the compressed air is recovered and used as combustion air for an open cycle gas turbine (OCGT) powerplant during which waste heat is recovered and heats the compressed air. The compressed air improves the efficiency of the OCGT and allows up to a 60% reduction in gas consumption compared to a conventional CCGT. CAES units can be operational within 14 minutes and there are two major plants in operation, one in Hundorf , Germany at 290 MW and another in McIntosh, Alabama at 110MW. Both were operational by 1991 and continue to be operational. The storage capacity ranges from 100-1000 MWh with an overall efficiency range of 70-79%. The lifetime of the technology is from 20-40 years.
Due to the requirement for particular geological formations of salt in strata, there are few places in the world which can implement this technology but the right conditions are present at Larne, Co. Antrim.
Gaelectric Energy Storage LTD. have been awarded the contract by the SPIRE Project to undertake the exploratory drilling and analysis of samples obtained. Two exploratory boreholes were drilled in late 2013 to assess the thickness and configuration of salt layers laid down in the Permian era and which lie between 500 and 800 metres below the surface. The information obtained on these salt layers will include salt type and quality, inclusions into the salt layer from igneous rock formations above, and a ‘picture’ of the overall salt deposit using sonar and radar technologies.
From the measurements obtained in this exploratory phase, technical assessment will be made of the suitability of these salt deposits for use as large compressed air storage caverns. In the event that the salt is suitable, a commercial possibility exists for the construction of a power plant of approximately 250 MW electrical output after the project is completed.
The extent of the impact that CAES or other storage technologies have on the market and the interplay between supply and demand is being modelled as part of the SPIRE project by the team at Ulster. Market models of the Irish and UK electricity markets are being tested to attempt to quantify the impact of changes to the markets using PLEXOS software. This modelling system has been benchmarked against previous years actual results to determine the accuracy of the models, and changes in energy uses, sources or new technologies like storage are modelled to estimate the effects that changing technologies will have on the markets.