The WA electricity market is known as the Wholesale Electricity Market (WEM). This market covers the south-west portion of the state generally bounded by Geraldton, Kalgoorlie, Albany and the Perth metropolitan area. Electricity customers here are served by the South West Interconnected System (SWIS).
Maximum electricity demand is highest on hot summer days, typically between 1pm and 8pm, with a peak at around 4pm. This is due to the widespread use of air conditioning systems to cool houses, shops and offices. Daily winter peaks are approximately 73% of summer peaks, and occur slightly later (around 6pm) when cooking and heating periods overlap.
The 200MW Collgar wind farm near Merredin is the latest example of the Federal Government target of 20% of total energy consumption being sourced from renewable fuels by 2020.
Energy output from wind farms, the most economic form of renewable supply at present, is not reliable, and as a result wind generation needs complementary supply from fast-response peaking diesel or gas fired capacity. This “energy balancing” service is highly valued by Western Power’s System Management, which has estimated that for every 100MW of wind capacity there may be a need for up to 60MW of fast-response peaking capacity to provide support.
As a result of the “peaky” profile of the SWIS, the Independent Market Operator of Western Australia (IMO) encourages the development of peaking power stations rather than baseload power stations. Peaking plants and super-peaking plants are cheaper to construct, but more expensive to operate than baseload stations due to higher fuel costs. Given that most peakers operate at only a few per cent capacity factor in any one year, the higher operating costs are less relevant than the initial capital cost.
Due to this Merredin Energy Pty Ltd (MEPL) has developed an 82MW open cycle gas turbine power station in Merredin, Western Australia. It comprises two efficient and low emmissions GE Frame 6B gas turbine generators, with associated plant, and operates as a peaking station. The plant runs on average for around 100 hours per year, mainly during periods of extremely hot weather in the Perth metropolitan area.
The power station is expected to have an operating life of approximately 25 years.
The power station is located at Lot 191, Robartson Road, Merredin, Western Australia; approximately 250km from Perth via the Great Eastern Highway.
The primary plant at the power station consists of two GE Frame-6B Model 6581 gas turbines with Brush Model BDAX 7-290 generator packages with a total nominal capacity of 82 MW.
The major items of ancillary plant that support the operation of the gas turbines comprise:
- Diesel fuel unloading, storage and forwarding system
- Water treatment plant with associated storage for raw water and demineralised water
- Sep-up transformer for each generator
- High voltage switchyard with connection through to the adjacent Western Power Merredin Terminal
- Fire protection system
- Integrated Control and Monitoring System
The plant operates on efficient and low emmissions fuel only. Merredin Energy has contracted with a local supplier to provide ultra-low sulphur distillate required.
The power station is connected to the South West Interconnected System (SWIS) via a single circuit 132kV overhead transmission line to Western Power’s Merredin Terminal north of the power station.