The additional capacity this will provide is only the first of a series of steps that are likely to double the amount of gas that will flow from the Pilbara to Perth in the next few years.

Already under consideration is a program that will cost $1 billion – in addition to more than $430 million currently being invested in the operation – to meet anticipated rapid increases in demand over the next few years.

This major expansion will meet demand expected between 2007 and 2009, nearly two years ahead of previous expectations.

The two compressors now being commissioned are the first of eight that will be progressively introduced into the pipeline over the next year, bringing to 26 the number augmenting gas flows. Ten new loops, totalling 217km, are being added to the 1600km line, and all compressor stations will finally have duplicate facilities, so that equipment failure should not disrupt the flow of gas.

It is not known how many compressors will be required in Stage 5 (the official name of the next ambitious phase). But the process of doubling output will probably require a complete duplication of the line.

The next phase is already subject to front-end engineering and design (FEED) and a decision is expected later this year.

DBP executive chairman Stuart Hohnen told EnergyReview.net that the consortium of owners – comprising DUET, Alcoa and Alinta – is pursuing an early commitment to the Stage 5 expansion.

“The Stage 4 expansion has met DBP’s obligation to spend at least $400m on expansion within five years and DBP is very keen to continue to expand the pipeline on commercial terms,” Hohnen said.

DBP was currently in discussion with prospective shippers for significant new demand that would support a further expansion of the pipeline, he claimed.

But several steps had to be taken before approval was given for the venture including agreements with gas suppliers and customers, funding, regulatory issues and gas specifications.

The consortium that purchased the pipeline in October 2004 is led by DUET – Diversified Utility and Energy Trusts, controlled by AMP and Macquarie. Alcoa and Alinta are the minority owners.

Their purchase of the pipeline, and other associated measures, ended a stalemate that had delayed its expansion for several years, caused by a dispute between the previous owner, Epic Energy, and the Western Australian regulator.