Over 125,000 homes and businesses went without power for two and a half hours, highlighting the need for investment in the troubled sector.

Western Australia's power supplies are being stretched by growing demand, ageing equipment and a dependence on the Dampier to Bunbury pipeline. However, questions are being asked about Western Power and Alinta's ability to grow with the times.

The company's 2003 Generation Status report claimed that Western Power will have just half the back up generation capacity it needs next year, regardless of whether the company's expansion program to meet future demand stays on track.

Western Power has a 'reserve margin' of 230 megawatts, a shortfall of 74 megawatts on the company's target 304MW back-up capacity, the amount required to maintain its Collie power plant.

That shortfall is also likely to double to 150 megawatts in 2004-05, while the back-up capacity will return to the required level in 2005-06, before another expected 100 megawatt shortfall in 2006-07.

These figures are also based on Alinta completing its 122MW co-generation plant at Alcoa's Pinjarra alumina refinery by mid-2005, although the project has yet to lock in a gas supply deal with the embattled Dampier to Bunbury gas pipeline.

Prior to the Collie plant failure last week Western Power said it might defer the construction of a new $350 million power plant in the south west as there is a number of smaller generators planned for construction over the next few years. The company's alternate plan was to work on extending the life of the current generators beyond their planned retirement date.

Friday's shutdown may have flicked the switch on that idea.