When Chris Davies, the head of future energy systems at the Australian Energy Market Operator, was at university, he says there were just 100 rooftop solar systems in the country. And even more recently, the idea that you could have more than 20 to 30 per cent wind and solar on the grid at any one time was laughed out of the room
But the energy market is changing rapidly, and so too is the understanding of the engineering around renewables and inverter-based technologies.
So much so, that records once considered impossible have been steadily falling in recent years. First there was 100 per cent instantaneous wind and solar on a megawatt scale grid on Australia’s King Island, then in the slightly larger Hawaiian island grids of Kaua’i and Maui.
Ireland has since reached 75 per cent penetration of variable renewables, as has the Texas grid, which is double the size of Australia’s National Electricity Market.
But even more spectacularly, in two multi gigawatt-scale local grids, Western Australia has reached 84 per cent and South Australia 92 per cent wind and solar, the latter even when a network issue meant it was effectively isolated from other state grids.
South Australia has since gone one better than that when, on New Year’s Eve last year, the amount of rooftop and distributed solar exceeded state demand for a brief period, although the state was able to export excess production at the time.
“This is purely phenomenal, absolutely phenomenal that we’ve reached this point,” Davies says. “When I was at uni, there were 100 houses in Australia that had solar on their roofs.
“So to be at a point where we could be supplying all the electricity from rooftop solar is just unbelievable. And what makes this possible is the engineering work and the policy work in South Australia to make that power system secure and to give us confidence in the performance of those devices.”
Davies was speaking on Thursday in a webinar hosted by AEMO on the subject of its newly released engineering roadmap, laying out the technical and operational requirements to allow Australia’s main grid to run on 100 per cent renewables, if only for short periods.
Those days are rapidly approaching. Already, enough wind and solar has been “available” to supply up to 99.7 per cent of demand at one particularly point, although the highest actual instantaneous penetration to date is 71 per cent.
And that number for actual penetration is lower largely because of economic curtailment, the decision by wind and/or solar farm owners to switch off their assets because wholesale prices are negative. But before AEMO can allow the 100 per cent penetration to actually occur, it needs to address and solve more engineering issues.
These are based mostly around grid security rather than supply issues, which is making sure that all the grid services such as inertia and system strength – traditionally delivered by fossil fuel generators – can be supplied by grid forming inverters and other technologies if the fossil fuel machines are turned off.
“I really think there is cause for optimism,” Davies says. “People might remember in the not too distant past, there was a pretty pervasive view circulating internationally that it wasn’t feasible to operate any power system with more than 20 to 30 per cent variable renewables on the system at any point in time.”
But that has been disproven, and Australia is leading the way in pushing new boundaries.
“So we’re at 42% average renewables in the national electricity market. And at the end of the day, that’s the number that matters.
“We’re aiming to lift that average. The federal government’s got targets of 82% average renewables by 2030 and so that’s the important number.
“If we lift the average, we are using less fossil fuels. There’s less emissions from our power system, and we are close to reaching our emission reduction targets. To do that, we’ve got to clear the engineering barriers so that at times, we can operate the power system out to, or very close to, 100% instantaneous renewables.”
The roadmap is being updated each year, and work is being funded by Arena, the government renewables agency, with $15 million allocated to the latest round.
Because of the prominence and popularity of rooftop solar, a lot of the work is going into managing those systems updating inverter standards, making sure installations are properly done, and providing protocols that allow the systems, if needed in an emergency, to be disconnected.
There is a new focus, too, on smaller solar systems which have hitherto escaped the scrutiny of Australia’s notoriously tough connection requirements, and AEMO will be releasing a discussion paper on that issue in a few months.
Work is also continuing on studying how far, and how securely, grid forming inverters can go to providing the essential grid services, including system strength and fault current, and to understanding to what extent spinning machines – in the form of synchronous condensers or coal and gas units that no longer burn fuel – will be needed.
Davies says the rate of investment and development in large scale renewables is still behind where it needs to be to get to the federal government targets, as well as the modelled “step change” scenario included in AEMO’s Integrated System Plan.
He cites, as the engineering roadmap does, that it’s not all about delays in planning and connections. The industry, he says, is also suffering from constraints and challenges in supply chains, labour force, contract agreements and financing.
“And what that means is that the annual install rate of new renewable capacity is currently lower than what it needs to be to meet 2030, emissions reduction targets for Australia,” he says.
“There is reason to be really positive about where we’re going, and I think also it is really exciting to see where we’re placed in the international context. But there is a lot more that needs to be done.”
