Larne CAES: a project update
A breakthrough in technology by Gaelectric’s partner company, Dresser-Rand, has led to the company choosing a site at Islandmagee. The deep salt formation (1,500m below ground level) and the nearby gas and grid infrastructure at Ballylumford make the site an optimal location for CAES. Conall Haughey explains the progress made.
Gaelectric started to plan for a CAES project for Ireland in 2008 and began its search for reserves in 2011. This resulted in a mineral licence application and the commencement of the environmental assessment (EIA) process for sites around Larne. The EIA and planning workstreams were converging in 2014 when a technology development provided a breakthrough for the project.
In basic terms, CAES takes air from the atmosphere, which is then compressed and stored underground. From there, it can be pumped at pressure into a turbine to generate electricity.
The project will deliver ancillary services and balancing for renewable generation and renewable energy’s advanced penetration of the electricity market. The company has applied the principle of alternatives throughout the planning process, including its consideration of the brining and electricity grid infrastructure. Following that analysis, the project will use surface trenching and horizontal directional drilling to build out the infrastructure and underground transportation for electricity.
Twenty-four sites were initially appraised and Carnduff was selected last summer due to the suitability of its salt deposits. The breakthrough came when technology partner Dresser-Rand was able to demonstrate its technology could be deployed at a greater depth than before i.e. down to 1,500m for Permian halite compared to the 600-900m depth envisaged at Carnduff.
A deeper salt system exists on nearby Islandmagee and Gaelectric is seeking to develop the plant site approximately located to Ballylumford power station, on the peninsula.
Two caverns will be constructed, as opposed to three at Carnduff. The length of the supporting infrastructure networks will also be shortened i.e. from 5.5km to less than 1km for the electricity grid, from 2km to 500m for gas transmission, and from 13km to less than 6km for brine pipeline infrastructure. The town of Larne will no longer be impacted by the project and details of this alternative option will be provided in the coming months.
Gaelectric is now seeking to develop the CAES project in a novel and innovative way by using Dresser-Rand’s SmartCAES solution. Gaelectric plans to install two 165MW trains, totalling 330MW, but the technology is modular and capacity can therefore be increased. Excess electrical power during off-peak hours is used to drive three air compressors, at low, medium and high pressures, with the air being cooled before it enters each compressor.
The air is then pumped into the cavern and is stored at pressures up to 2,800psi. The plant goes into generation mode when consumer demand is high with the compressed air being released into a recuperator chamber where it is heated to 600°F (315°C).
This hot air is then expanded in a very high pressure turbine and heated to around 1,000°F (537°C) in a high pressure turbine and 1,600°F (871°C) in a low pressure turbine which is used to drive the generator.
The discharged air returns to the recuperator before being released into the atmosphere at around 180°F (82°C). Ninety per cent of the heat is recovered and converted into electricity.
When consumer demand is moderate, the system can produce electricity while simultaneously diverting compressed air for storage.
The technological advance achieved last year considerably simplifies the project’s infrastructural aspects and reduces its economic and environmental footprint.
The next project milestone is to submit the EIA and planning workstream in Q3 2015 and the company is looking forward to support from other stakeholders as it prepares for the final phase of the planning process.
Significant economic benefits
Almost 600 new jobs will be created from the £300 million investment in the Larne CAES project, according to independent analysis by PMCA Economic Consulting. The project has been classified as a European Project of Common Interest (PCI) and harnesses Northern Ireland’s innate advantages in wind power and geology to attract inward investment.
The construction phase for CAES is expected to boost economic activity in Northern Ireland by £161 million, resulting in an extra £46 million gross value added, and leading to the creation of 532 new full-time equivalent jobs: 200 directly attributable to the project and a further 332 indirectly or through the induced effects of investment.
