Mondarra to pump state's back-up gas

When the Varanus Island gas explosion occurred in 2008, wiping out a third of Western Australia’s gas supplies and causing $3 billion in damage to the state’s economy, securing an alternative energy source in case of an emergency became paramount.

That contingency gas supply becomes available late next month when the Mondarra gas storage facility, near Dongara, begins operations, following recent expansions and upgrades to gas compression and processing facilities.

Built by gas infrastructure business APA Group, Mondarra currently has one major customer, generator Verve Energy, which signed a 20-year contract in 2011, and is in active discussions with several potential customers, known to be major gas users in WA, for the remainder of the storage capacity.

Mondarra has a storage capacity of 15 petajoules (PJ), about two months’ worth of WA gas supply, which can be released at a rate of 150 terajoules (TJ) per day through the Dampier to Bunbury pipeline or the Parmelia pipeline.

Verve has the capacity to withdraw 90TJ/day and, with its 60 per cent ownership of Mondarra’s storage capacity, can store enough gas at the site to keep its gas-fired generation operating for peak demand periods up to 30 days and a declining supply for a further 30 days.

The WA government said the Mondarra facility, which is built on a depleted gas reservoir in Dongara, 65 kilometres south of Geraldton, will enable Verve to manage its exposure to its gas supply and significantly reduce its costs.

APA Mondarra project manager Aidan Trend said customers could use the gas stored on site to manage supply and demand as they saw fit, withdrawing and delivering gas to pipelines at their request.

A Verve spokesperson said the electricity supplier would manage its gas storage and extraction depending on operational requirements.

The state government said the facility would primarily contribute to increased security and reliability of energy supplies.

“The Mondarra gas storage facility contributes to securing energy security for the South West of WA by optimising the use of existing gas supplies, thereby minimising costs,” a spokesman for the energy minister said.

“(It will provide) gas in the event of an upstream gas disruption, contribute to a more liquid and mature gas market and increase the ability of downstream gas customers to manage risks when entering long-term gas contracts.”