It’s a unique solution, says Doug Walker, executive chairman of Zenith Energy, the independent power producer that will soon integrate solar with medium-speed diesel generation, to deliver what Independence Group’s (IGO) chief operating officer, Rob Dennis, describes as an “excellent power station with excellent fuel economy”.
IGO has a 10-year power-purchase agreement with Zenith, which designed and financed this innovative, stand-alone energy system, and is already operating the first phase of power generation.
The diesel-fuelled engines, manufactured by GE at its US transportation plant in Erie, Pennsylvania, are distributed in Australia by RJE, Adelaide-based designers and builders of plant and power solutions for industry. RJE packages the robust, long-life engines into generator sets tailored for various stationary power applications.
In this first Australian stationary application of the loco-derivative engines, RJE worked with Zenith Energy to tailor a generator solution that can consistently supply the power demands of the mine.
Can-do loco engines partner with the sun
The “beauty” of these medium-speed generators, says Walker is that their output can be flexible in responding to the cloud-cover dips and the sun-down troughs that will occur when a 7MW solar array is integrated into the solution—and that such variations in demand make barely any difference to their fuel usage.
“The flat fuel consumption and efficiency of the GE engines enable us this integration flexibility,” says Walker.
Each 3MW, 50-tonne genset—engine, alternator, engine mounts, frame—was assembled in Adelaide and transported 3,000km by truck to the mine: “We drove across the Nullarbor and turned right into the Nova site about 120km before Norseman,” says Michael White, general manager of Energy & Renewables at RJE Global.
Some 220km south of Kalgoorlie and 38km from the Eyre Highway, the Nova Nickel Project is way off the grid. Its electricity-thirsty infrastructure includes the underground mine, with kilometres of tunnels through which trucks operate to bring ore rich in nickel and copper to the surface; a crushing plant, two semi-autogenous grinding (SAG) mills, a ball mill and sulphide flotation plant; accommodation and facilities for 500 workers, a 2km air strip, a sealed access road to the Highway, and a water-supply system.
Choosing medium-speed diesel engines over the more typically applied high-speed diesel generators to provide base-load power already saves IGO 3% to 5% on its annual fuel bill. The plan to hook up to the sun via a solar farm will reduce the miner’s diesel consumption by 3 million litres a year—and save the environment some 8,000 tonnes of CO2.
Solar alone cannot yet power a 24-hour mining operation. “When cloud comes over, we may see a 40-50% reduction in output from the solar farm,” says Walker. “So we need to have capacity online to take up that reduction in output.”
Making Australian nickel more competitive
And because these engines run at medium speed, they also require less frequent service and overhaul than their high-speed cousins. For example, they have four to eight times the duration between oil changes.
Jess Goh, local sales director for GE Marine, Stationary & Drilling (MS&D), adds that, “Where a high-speed engine has typically required two overhauls and needs a major rebuild after 20,000 hours of operation, this slower, steadier engine may not require even a first overhaul until it reaches 30,000 hours of medium duty-cycle operation.”
MS&D was established more than a decade ago to harness the reliability and fuel efficiency of the locomotive engines to other applications. More than 100 of its diesel-engine gensets have been sold in Africa alone, mostly to remote mining operations.
Goh has been revving up awareness of the engine’s capabilities in Australia and the Pacific region. She has projects in train that put the locomotion into dredging vessels and tuna-fishing boats; and, more on the stationary side, into a power station for the island of Chuuk in Micronesia, for which the gensets were also designed and packaged by RJE.
“The capital expenditure on our medium-speed engines is higher than on high-speed engines, and the implementation takes a bit longer, so you need the project to be of a certain tenure,” says Goh. “Match this engine to the right application and you’ll break even after the first year of operation and start making savings thereafter.”
The Nova mine has a life expectancy of 10-12 years, and savings in fuel, downtime and reduced maintenance staff are set to stack up later this year for power provider Zenith Energy, given that the generator plant began commercial operation in 2016.
In the throes of finalising finance for the solar component of the Nova installation, Walker tells the story of how he’d just made the decision to go ahead with GE’s medium-speed diesel engines for baseload power when, “I met Rio Tinto’s reliability engineer for locomotives at a social function. He was glowing in his reports of these engines, and that really made me feel comfortable with my big investment... So far, everything he said has proved to be correct.”