The Directors of Portland Gas plc says that the Company has filed a patent application to the UK Intellectual Property Office describing a system to allow ‘cushion gas’ within a conventional salt cavern to be removed in times of high demand or national emergencies.

For any storage system the gas must be stored at a pressure that is maintained within acceptable limits. To accomplish this, conventional gas storage systems require that a volume of cushion gas is retained at all times to maintain the gas pressure above an acceptable minimum threshold level. The invention allows for the removal of the cushion gas from a cavern during a period of high gas demand by moving a fluid into the cavern to maintain an acceptable pressure of the gas in the cavern.

Commenting on the method, Andrew Hindle, CEO of Portland Gas plc, stated "The effective storage capacity of the cavern is increased and the cushion gas can be viewed as a strategic asset available at times of acute need for the supply of gas to markets.

"In the case of our Northern Ireland project at Larne Lough, we will be reviewing the feasibility of using seawater to displace the cushion gas in times of a national emergency or very high demand. The cushion gas could provide an additional volume of approximately 290 million cubic metres (‘mcm’) to the proposed normal ‘working gas’ of 500 mcm. Portland Gas estimates this could provide an additional 13 days of supplies to the island of Ireland market in the latter part of the next decade if the project goes ahead. The availability of this gas to the market, particularly at the end of winter when conventional gas stocks are low, would add significantly to security of supply for the island of Ireland and add to other proposed production and import projects, together with other joint initiatives of the Department of Communications, Energy and Natural Resources and the Department of Enterprise, Trade and Investment, Northern Ireland."

Tags: Portland Gas plc