Solar farm construction method to reduce dust and save ‘bonsai forest’
A new technique to preserve native vegetation and reduce dust is being rolled out during construction of a solar farm in South Australia.
The method, developed by South Australian company Succession Ecology, involves the use of a roller to flatten vegetation ahead of panel installation rather than tearing up the landscape with a grader.
It will be used at the 280MW Cultana Solar Farm when construction begins later this year following a successful trial of the method at the 1100-hectare site in December 2018.
Solar farms in arid and semi-arid zones are notorious for generating large amounts of dust, which not only plague local communities but also lead to the reduced performance of panels and require large amounts of water and other suppressants to control.
Succession Ecology’s Glenn Christie came up with the idea after leading a project to revegetate the former ash dam at a decommissioned coal-fired power station at Port Augusta in South Australia in 2017 and 2018.
He said the use of a smooth 20-tonne roller in the solar farm trial flattened the plants and the ground without breaking the surface.
“It was a bit of lightbulb moment — it’s not just about revegetation and biodiversity, there can be really practical outcomes so applying it to a solar farm made sense,” Christie said.
“These plants such as saltbush and bluebush have such deep root systems that reach down metres and metres because they have to be able to withstand five-year droughts.
“The roller sort of stunts the plant and puts it into a kind of sleep mode for three to six months and that’s the time that you need to have all of the construction happening.”
The Cultana Solar Farm site is on an 1100ha site 10km to the north of the township of Whyalla, which is about 350km northwest of the South Australian capital Adelaide.
Although some western myall trees would have to be cleared from the site, Christie described the site as a “bonsai forest” because the majority of the native vegetation were “knee-highs” and “ankle-biters”.
He said flattening the ground with a roller instead of a grader was slightly cheaper and also reduced the need for water trucks to suppress dust and dump trucks to remove debris.
“Then there are the cost savings when it’s operating — if you’ve got less dust you’ve got more production from the panels, less cleaning costs,” Christie said.
“And if the bonsai forest works as we expect, it will lead to lower temperatures on the ground, which means the panels themselves will be cooler and will produce better.
“We really want to nail down the economics and then we can roll it out in any arid or semi-arid area in Australia or elsewhere in the world.”
Construction of the Cultana Solar Farm could begin as early as July, pending final regulatory approvals.
The project is the first large scale project in billionaire industrialist Sanjeev Gupta’s plan to generate one gigawatt of dispatchable renewable energy in South Australia to aid his green steel production.
SIMEC Energy Australia is part of Gupta’s GFG Alliance and is delivering the project through an Engineer, Procure and Construction (EPC) partnership with Shanghai Electric.
SIMEC CEO Marc Barrington said final regulatory approvals and a transmission connection agreement were expected in the coming months with financial close on track for the July Quarter of this year.
He said the planned 13–15 month construction period could then commence straight away with potential completion by the end of 2021.
“All of our financing is sorted and our contracting structure is all sorted, really it’s just awaiting the outcome of the regulatory processes,” Barrington said.
“We’re already going to tender at the moment for a whole bunch of works — everything from perimeter fencing through to security service providers and we’ve undertaken many phases of early works so we can go very quickly once we get those final regulatory approvals.”
The site is to the north of GFG’s Whyalla Steelworks and is set to house 780,000 solar panels capable of generating 600GWh of energy generation per year, enough to power 96,000 homes.
Barrington said the rolling would be done in sections just ahead of where the panel installation was taking place and would not disturb vegetation between panel rows.
He said maintaining vegetation and biodiversity were not the only benefit of Christie’s rolling technique as the groundcover helped suppress dust, which had caused problems at other arid zone solar farms.
“We’ve trialled it on site and it certainly works — it creates a great environment for the flattened saltbush to regrow because there’s already vegetation that’s alive and growing but it’s also economically good for the project because you need to use less water for dust suppression and helps keeps the panels clean,” he said.
“Dust is a huge inhibitor to generation for solar panels so we think that’s going to give it dividends as well.
Barrington said the project would also be the first of its kind in Australia to use an automated robotic vehicle to clean the panels with compressed air and brushes, helping to limit the use of water on the site.
“There’s a benefit to the environment we’re going to be occupying but also there’s a commercial benefit in the panels maintaining their efficiency and there’s a massive community benefit in making sure you’re not creating dust issues, which is not just about people’s washing, it’s about the habitability of the place.
“I really hope that Glenn’s work takes off and I hope it’s used not just in Australia but globally.
“There’s plenty of places in Texas and Nevada and other parts of North America with similar sorts of environments so there are plenty of opportunities for it to be rolled out.”
Christie presented a paper on his native revegetation techniques and seed collection practices to a mining rehabilitation conference in Perth, Western Australia last year.
He said former mining sites and degraded pastoral country were also suitable for his revegetation techniques and existing solar farms could be “retrofitted” with low growing vegetation to reduce dust.
“As far as we can tell we cannot find this practical ecology work being done on such a scale at solar farms anywhere in the world at the moment but it is an idea that once it’s costed and presented it should take off like wildfire and hopefully people will want to come and see what we’re doing here in South Australia.
“My big dream is to use these skills we’re learning at solar farms to rehabilitate mining sites, pastoral country and ultimately deserts.
“It’s also about planting plants that plant themselves. We put the initial seed in like a farmer and then the plants do the work from there on by seeding in the gaps and self-assembling.”