Important security of supply benefits
The proposed gas storage facility will make a significant contribution to the security of gas supplies for the whole island of Ireland. Ireland is dependent on gas for around 60% of electricity generation with the majority of the island’s gas imported via a single pipeline from Scotland. The facility will provide critical Security of Supply and flexibility to the Irish network to support the demand to back up increasingly variable wind power output. When complete, it will store enough gas to satisfy the island of Ireland’s peak demand for up to 15 days.
Additionally, salt cavern gas storage provides much-needed flexibility when compared to other storage methods. The facility will be able to switch from injection to withdrawal quickly to cater for short-term spikes in demand such as a cold spell or a period of low wind generation which increases the load on gas fired generation.
Northern Ireland, through its connection to Scotland, relies on North Sea gas to meet its average demand and provide the flexibility to meet peaks in demand. North Sea gas supplies are depleting and GB is moving towards south of England for its gas supplies via imported LNG. Salt cavern gas storage will protect Ireland against the effects of a weakening GB connection point.
Strong transmission infrastructure is already in place to link the facility to all demand locations. Gas from the facility will be able to feed the Ireland onshore network via the South-North pipeline and via the Scotland to Northern Ireland pipeline and through the existing subsea interconnectors.
Northern Ireland has a target to generate 40% of electricity from renewables by 2020 – this will primarily be achieved through wind-powered generation. A shift to renewable energy sources is likely to result in an increasing reliance on gas-fired power stations to support the fluctuations in supply from the intermittent nature of wind. Rapid cycle gas storage facilities, such as this planned project, will be important to respond to the rapidly fluctuating gas supply demands for electricity generation.
Ideal location, unique on the island
The Larne area is the only location on the island or Ireland with suitable geology for salt cavern gas storage. Gas will be stored in eight storage caverns, each approximately 80m in diameter and 150m in height, which will be created within a layer of salt with an average thickness of more than 200m located approximately 1,300m beneath Larne Lough. The salt layer has high purity and low overall insoluble content and is suitable for cavern construction over its entire thickness.
The proposed site is ideally located close to the sea and already possesses the two main supporting infrastructural requirements for a gas storage facility – a source of power (adjacent to Ballylumford power station where the electricity grid is very strong) and a connection to the main gas network (the Ballylumford pressure reduction station is the connection point to the Scotland-Northern Ireland gas pipeline).
Infrastructure and suitable geology
European Union (“EU”) support
In 2013 the project was given PCI status by the European Commission and included on a Europe wide list of the most important energy projects. PCI status means recognition by the European authorities that the Islandmagee gas storage project brings benefits not only to the Member State in which it is located, but to a much wider area. This provides confirmation of the importance of the project at a European level.
PCI status means that the project must be given priority and quick passage by relevant Member States in the permitting process, and cooperation in its development as well as being eligible to apply for significant financial support from the European Union.
In 2015, the project’s PCI status was renewed for a further two years – the only gas storage project in Western Europe to have this designation. The EU has provided grant funding to the project in 2015 and 2016.
The project will create more than 20 high quality permanent jobs, with construction activities generating temporary employment for over 200 people and knock-on indirect business for support services and many more.
Gas storage also has the potential to reduce volatility in energy prices – with the option of purchasing gas for storage when prices are low for use or sale when prices are higher.
The project is being developed as a commercial venture, with no cost incurring to the energy consumers.
How gas storage works
Up to eight storage caverns, each approximately 80m in diameter and 150m in height are proposed at Islandmagee. The caverns are created by a technique known as ‘leaching’ or ‘solution mining’, which dissolves the salt, under controlled conditions, and creates a cavern deep underground in the salt layer in which gas can be stored. The facility expects to have an injection capability of 12 million cubic metres per day of gas and a maximum withdrawal capability of 22 million cubic metres of gas per day.
The diagram below illustrates the proportions and depth below ground of the proposed caverns.
Proposed salt caverns
Safe and environmentally responsible
The use of salt strata to create underground storage caverns deep underground is one of the safest and most environmentally friendly methods of storing large quantities of natural gas.
Gas storage technology is tried and tested all over the world, with more than 70 salt storage facilities in operation, with more under construction. Currently about one third of the operational facilities are located in Europe, with the majority in Germany, country with some of the most stringent safety requirements.
The Islandmagee facility will conform to the UK HSE regulations, and will include a number of safety features, including sub-surface safety valves, to isolate gas stored in the caverns.
The estimated timescale for the whole project is approximately seven years, although this actually covers three almost separate construction projects of 2-3 years each in different locations on Islandmagee. The first cavern would become operational after five years. In the intervening period much more wind generation is planned for the island and North Sea gas supplies will further deplete, making it even more important that this facility is developed without delay.
The strategic benefits of a project such as the Islandmagee Storage project have long been recognised by both the NI and ROI governments and regulators as well as more recently by the European Union.