Dumping diesel

A remote WA goldmine’s hybrid renewable microgrid has seen its diesel use halved. The project’s success provides proof of concept for turning the mining industry to renewables, writes Marie Low.

The Agnew Gold Mine, in south-central Western Australia, fills the familiar descriptor “isolated WA mining site” in just about every way. The mine is roughly 1000 kilometres north-east of Perth. It employs about 400 people, three-quarters of them contractors, most fly-in/fly-out. The nearest town is Leinster, population 700-ish – a borough established in the 1970s expressly as a mining dormitory town.

Given the isolation, it’s perhaps against the odds that, just over two years ago, Agnew commissioned the country’s biggest hybrid renewable energy microgrid.

At the time, the Agnew Hybrid Renewable Microgrid was described as a “guinea pig” project. Stuart Mathews, Executive Vice President Australasia of the mine’s owner Gold Fields, said at the project’s opening the Agnew microgrid was “groundbreaking”.

“This project has provided a framework to take innovative energy solutions further across Gold Fields’ mine sites both in Australia and around the world,” Mathews said.

So just how has this microgrid, owned and operated by power supplier EDL, performed so far?

The microgrid officially opened in November 2021 but it actually began operations more than a year in advance, in mid-2020. It made Agnew the first mine in Australia to be predominantly powered by wind-generated electricity.

The set-up includes five energy technologies: five wind turbines delivering 18 megawatts; a 4MW solar farm; a 13MW/4MWh battery energy storage system; an off-grid 21MW gas/diesel engine power plant; and advanced microgrid control systems.

EDL Chief Executive Officer James Harman says that “the Agnew project has exceeded expectations, providing 55–60% of the mine’s energy requirements daily, and more than 80% in optimum weather conditions.”

Diesel and electricity emissions at the site have reduced by 42%.

At the time of commissioning, the grid emissions factor (the amount of CO2 emissions intensity per unit of electricity generation in the system) more than halved – from approximately 0.59 tonnes of CO2 per MWh to 0.27tCO2-e/MWh, according to the “Knowledge Sharing Final Report” prepared for the Australian Renewable Energy Agency (ARENA )by Gold Fields.

EDL’s General Manager Remote Energy, Geoff Hobley, says the project did not come without its share of challenges. Aside from the obvious logistical nightmare of transporting huge equipment – including the 70-metre-long turbine blades for five turbines cross-country to Leinster – this venture into renewables straddled global turmoil.

“Agnew was commissioned during the early stages of the COVID-19 pandemic, which meant dealing with travel restrictions,” Hobley says.

“Specialised team members and equipment were required from interstate and overseas, adding complexity to the commissioning process and placing additional pressure on our people.”

Hobley says the pioneering aspect of the project in integrating wind, solar, a battery system, a control system to manage power delivery and an underlying thermal power station (gas or diesel-powered) for continuity of power added to the complexity.

“Operationally, the thermal generators in a hybrid power solution are required to work differently from their usual application in a traditional ‘thermal only’ solution,” he says.

“This can place additional stress on the thermal generators as they often operate at lower loads. Interestingly, the renewable generation assets are often the easiest to manage, as they operate most closely to their intended design.”

Sometimes issues only become apparent after a system is operational. At Agnew, there have been some challenges in meshing the variable wind resource with the thermal station operations.

Agnew has committed to day-ahead wind forecasting by June 2024; currently it only has predictive solar technology. EDL’s Operations Manager Remote Energy WA, Paul White, says that finding suitably experienced people to run the microgrid has also been a challenge, particularly in a tight jobs market. So EDL has developed onsite microgrid training to help overcome this.

On the whole, Hobley says, any issues have been relatively minor.

“Most of these are now resolved and other solutions are under development,” he says. “These lessons are incorporated to optimise performance and inform future projects.”

Agnew is still the largest hybrid renewable microgrid in Australia. Hobley says EDL will use what they have learnt for future projects.

While Agnew has been designed to run with some thermal generators running at any time, EDL also operates a number of other hybrid renewable projects that can operate for periods on 100% renewable energy.

The Denham Hydrogen Demonstration Plant is believed to be one of the first of its kind worldwide, and late last year it began producing hydrogen by electrolysis

The Coober Pedy Hybrid Renewable Power Station, which powers the remote opal-mining town in South Australia, has at times reached 100% renewable energy, and the Jabiru Hybrid Renewable Power Station in the Northern Territory draws on 100% solar energy during the day, with excess stored in a battery. Jabiru’s commissioning has seen a 1.7 million litre yearly reduction in diesel use.

Hobley says EDL also has other projects in development with mines in regional and remote Australia, some seeking to “set new world benchmarks for low-carbon mining operations”.

“It is an exciting time to be working in this industry, delivering world-leading solutions to a market that demands low-carbon energy,” he says.

Gold Fields’ Knowledge Sharing Final Report says that the Agnew project’s success has become well known. The report states:

“This awareness has given industry a measure of confidence that projects of this nature are viable and that the ‘guinea pig’ for high-penetration microgrids has survived.” 

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More micro success – with hydrogen

Nestled on the shores of beautiful Shark Bay, 820km north of Perth, Denham seems an unlikely place for Australia’s first green-hydrogen-fuelled microgrid. In fact, the project is believed to be one of the first of its kind worldwide, and late last year it began producing hydrogen by electrolysis.

Expected to hit full swing in early 2023, the $9.3 million Denham Hydrogen Demonstration Plant is expected to provide enough power for about 100 homes – or 20% of Denham’s small population. The bulk of funding for the project – $5.7 million – came from the WA Government, with a further $1 million through the WA Renewable Hydrogen Fund and $2.6 million from the Australian Renewable Energy Agency (ARENA).

Horizon Power and Hybrid Systems Australia are delivering the project, which includes a 704kW solar farm, a 348kW hydrogen electrolyser, and a 100kW hydrogen fuel cell as an alternative to diesel generators. It has been built at the site of the town’s existing power station.

Horizon Power says the project should offset 140,000 litres of diesel a year, and that other remote diesel microgrids might take the same path after 2025.

Hybrid Systems’ executive director Mike Hall says the system aims to demonstrate the efficiency of the hydrogen equipment, the ramp rate of hydrogen (the speed at which a hydrogen-powered generator can increase and decrease capacity), and the efficiency and storage capability of hydrogen fuel cells compared to batteries.

“As an industry-first, this project has presented some really interesting opportunities for us to grow our capabilities in the green hydrogen project delivery space,” Hall says. “It’s still a budding industry in Australia, so we really had to start at the beginning, from designing a system based on first-principle thinking to navigating both existing and newly developing industry regulations and licensing designed for different applications.”

Shire of Shark Bay Council agreed early in the proposal to lease 20 hectares of land for the project.

“A benefit of the ‘green hydrogen to electricity’ supply chain is that storage of hydrogen ensures power 24/7,” Council president Cheryl Cowell says, adding that the test to prove the reliability of a hydrogen powerplant could “provide an opportunity to expand and supply full power requirements for Denham in the future.”

Cowell says Horizon wants to eventually replace Denham’s diesel generators with renewable energy, with a goal to have no new diesel power generation from 2025.

“The Denham trial … may solve the problem of transporting power long distances across the State,” she says. “The lower cost of photovoltaics means that megawatts of power can be supplied to customers, a much less costly exercise.”

The trial goes hand-in-hand, Cowell says, with the community’s appreciation of living surrounded by WA’s first World Heritage Area – Shark Bay, which was inscribed on the UNESCO list in 1991.

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This article is part of the Greenlight Project. The Greenlight Project looks at how regional Australia is preparing for and adapting to climate change.