Snowy Hydro refit is powering ahead

Canberra Times
Monday 24/5/2010 Page: 2

By any measure, judgment day is an ambitious timeline. Sixty years ago men blasting tunnels through the Snowy Mountains set themselves such a towering goal, singing, "Roll on your way until judgment day, Snowy River roll." Long after the echoes had died away and the dust cleared, seven major power stations, 16 dams, and 145km of interconnected tunnels still fill the country with pride and generate about 70% of Australia's renewable energy.

In the midst of a $400 million upgrade of the post-war project, Snowy Hydro's modernisation engineer-in-charge Darren Davis likens the overhaul to a brain and heart transplant. He said his predecessors designed the Snowy's machinery to be dismantled and upgraded so it could be renewed and would last until judgment day. Smaller and smarter components are replacing ageing circuit breakers, high voltage transformers and cables. New turbine runners are optimising generation capabilities and improving efficiency. "Digging back through records we've found strip down procedures, diagrams, drawings and designs of jigs and fixtures," Mr Davis said.

The highest of all the Snowy's power stations is a run-of-the-river power station at Guthega. The scheme's first and smallest power station built in the 1950s, Guthega's floor is littered with history. An English Electric Co, engine sits at the foot of a turbine displaying a sign saying it was made in Britain. Two turbines and ancillary equipment have been working away for 60 years at the foot of a 246.9m drop from Guthega Dam, generating as much power as the wind farm at Lake George.

Now 40 specialist engineers, tradespeople and contractors are overhauling 1920s-designed machines and pulling out poor-quality post-war steel showing signs of fatigue. "It was well and truly due for a birthday," Mr Davis said. "We have a fairly robust condition assessment process before we make the decision to go into overhauls, some of the conditions we can't find until we strip down machines." A mix of national and international hydro companies, suppliers and skilled workers in electricity generation will take about seven years to complete the work.

Replacing turbine runners is straightforward but time consuming. Only one of the two units at Guthega will be out of service at any time. "It takes its about 18 months to two years from the time we decide to upgrade a unit, get the runner ready to install.There's a long, long process of computation fluid dynamics and scale models before we get full-size units." Each generating unit rated at 30MW will produce at least 34MW after the upgrade and will be up to 5% more efficient.

While wind and solar energy are attracting much investment in renewable energy, hydro power's role remains critical, according to Mr Davis. "I don't quite understand why hydro does not get the same kudos as wind or solar, you get far more power out of hydro than wind or solar. "With wind you are talking one or twoMWs per machine, we have machines that have 300MWs per machine - you have to build a lot of wind machines to get the same output. "We have a limited fuel supply, we can't run all the time because we run out of water, but we can torn it on and off. Wind has an unlimited but uncertain supply."

While Snowy Hydro's power would come on in two minutes, gas-fired stations could take up to 30 minutes and coal-fired stations could take ]tours. "Peaking is our forte, that fits neatly with a limited fuel supply, we don't have a lot of water, we are best using it at the peak." Guthega's upgrade is being commissioned this month and will be returned to service in June.