Controlling the curve

Western Australia’s Kwinana Power Station
Western Australia’s Kwinana Power Station

The latest in gas turbine technology capable of maintaining efficiency across the load curve has been installed at Western Australia’s Kwinana Power Station, adding 200MW of high-efficiency gas turbine plant to Verve Energy’s portfolio.

Fast facts:

• HEGTs are up to 43 per cent more efficient at full load than the plant they replace

• Sustained hot day performance

• ‘Fast start’ capabilities
(about 12 minutes to full load)

• Can handle stop-start operating conditions that are damaging to other plant not designed for that type of operation

• Flexibility to provide power at part-load as efficiently as most gas turbines at full load

• No maintenance penalty for multiple stop-start cycles per day

Groundbreaking open-cycle gas technology is currently undergoing final reliability testing 40km south of Perth. Two General Electric LMS10 100MW open-cycle high-efficiency gas turbines (HEGT) are in the final stages of commissioning by UGL at Kwinana Power Station. The $300 million HEGTs, of which the State Government funded $263 million, will help maintain a secure supply of electricity and meet demand for power in Western Australia.

WA Energy Minister Peter Collier officially opened the HEGTs in June.

The machines, derivative of the engines on large passenger aircraft, combine excellent efficiency and extremely flexible operating capabilities. In particular their fast-start capability (10 minutes to full load) is perfect for the South West Interconnected System (SWIS) and Verve Energy’s system balancing obligations, particularly in supporting wind power in the system.

“They replace older generators at Kwinana Power Station, reinforce the security of power supplies in WA as demand continues to grow and will assist Verve Energy’s balancing operations in the WA power system, in particular in supporting its unique role in driving renewable energy platforms in WA,” Mr Collier said.

The HEGTs have a very flat efficiency curve, making better use of fuel and maintaining power even at half load. Verve Energy has found this highly beneficial, considering most gas turbines on the SWIS spend much of their time at 50 per cent load or below as they wait in support.

“Fuel is one of our biggest costs. So, fuel savings are very important obviously,” Verve Energy gas turbines and sustainable operations manager Peter South told Energy Source & Distribution.

“The big thing about these machines is their ability to maintain their efficiency across the load curve. [A] typical frame gas turbine, when it gets down to half load… can do about 30-32 per cent efficiency. And that’s compared to 46 for the HEGTs.”

The first of its kind to be built in Australia, the power plant is significant in that it’s thermal efficiency is almost as good as that of a combined-cycle plant, but without the attendant infrastructure.

“You’re looking at a much lighter, cheaper, more automatic plant that doesn’t require operators, doesn’t have a boiler and hasn’t got a steam turbine. So the whole capital cost is lower, it’s much more flexible and it’s giving you similar efficiencies,” Mr South explained.

“That’s a significant step forward in technology from an industry perspective, from an environmental perspective, from a sustainability of future generation perspective. So the idea is it’s a big step forward.”

Kwinana Power Station is unique in WA in that it can burn three fuels – coal, gas and oil. Connected by 66,000v, 132,000v and 330,000v transmission lines to the South West Interconnected System (SWIS), in an area that stretches north to Kalbarri, south to Albany and east to Kalgoorlie, Verve Energy runs its open-cycle gas turbines completely unattended. The plant is controlled remotely by a team of 20 people responsible for more than 1000MW across the state.

“Most people tend to have at least one or two operators. Our philosophy is, put them in a paddock, leave them alone and you tend to them as required remotely. And they tend to go better that way,” Mr South said.

The HEGTs were built on the site of two 35-year-old gas-fired generating units, Stage B, which were demolished in 2011. Gas freed up by the shutdown of Stage B is being used by the new HEGTs. In the interests of energy security, the HEGTs can also burn distillate.

The technology continues Verve Energy’s transition in the competitive electricity market. Mr South said the gas technology represented a foothold in some “very important” technology.

“No one’s quite sure where the industry is going in terms of what’s going to be next big thing and what’s going to be the next technology. It’s good to be able to have some knowledge of the various technologies. Now this one seems to have a place in the future and its good to be one of the first people in it,” Mr South said.