Let’s start with the ABCs: what are inertia services on an electricity grid? Even before that, what is inertia in a grid setting? Most of us should remember “inertia” from our younger years in primary school. Inertia is an object’s natural inclination to just keep moving (if it weren’t for friction) or just keep sitting still if that object is not moving. But on the surface, that’s confusing in terms of electricity, until you think a bit about how electricity is generated in old-school thermal power plants. I’ll let the UK’s National Grid ESO explain:
“Many generators producing electricity for the grid have spinning parts — they rotate at the right frequency to help balance supply and demand and can spin faster or slower if needed.
“The kinetic energy ‘stored’ in these spinning parts is our system inertia. If there’s a sudden change in system frequency, these parts will carry on spinning — even if the generator itself has lost power — and slow down that change (what we call the rate of change of frequency) while our control room restores balance.
“Inertia behaves a bit like the shock absorbers in your car’s suspension, which dampen the effect of a sudden bump in the road and keep your car stable and moving forward.”
Solar and wind power don’t provide these inertia services for the grid, so grid operators need to find something else to rely on instead of coal and natural gas power plants in order to avoid turning on old coal power plants to provide that service as more renewables get built. After all, what’s the point of renewables if coal power is running in the background in order to help with frequency regulation and inertia.
As CleanTechnica readers know by now, batteries are critical here. I’ll lean on one more explanation of grid inertia to move onto that, this one from the UK’s Energy Research Accelerator: “Grid inertia is a form of energy storage which addresses imbalances between supply and demand on electricity grids over very short time periods, typically on the order of fractions of a second to several seconds.” While coal and gas power plants can help with those imbalances, nothing beats the speed and capability of actual batteries in dealing with this challenge. And now we have a prime example at a large scale.
Tesla’s “Big Battery” in South Australia got approval from the Australian Energy Market Operator to provide inertia services for the National Electricity Market in Australia. Neoen, which owns and operates the 150 MW/193.5MWh Hornsdale battery (aka Hornsdale Power Reserve), claims that this is the first large-scale battery providing inertia services in the world. The Big Battery is able to provide ~2,000 “megawatt seconds” (MWs) of an inertia equivalency to help keep the grid stable. It does so via Tesla’s Virtual Machine Mode service.
Most of us don’t know anything about megawatt seconds. How much is this Big Battery helping by getting into the inertia services business in South Australia? According to Neoen, it will be able to provide ~15% of South Australia’s inertia shortfall.
South Australia now has a whopping 64% of its electricity coming from renewable energy. The state’s grid serves around 1.7 million people and around 150,000 businesses.
“Grid-scale big batteries in Australia find themselves in a funny position today where the technology is capable of providing multiple grid services, including fast frequency response, frequency regulation and energy arbitrage, and now — with advanced inverters — inertia. The issue is there are no markets yet to reward this full value stack,” pv magazine notes.
“We are delighted to announce the successful deployment of inertia at Hornsdale Power Reserve. This achievement was forged through outstanding teamwork: I’d like to acknowledge the dedication of our team and our long-term partners at Tesla, as well as our trusted counterparts at AEMO and ElectraNet,” Louis de Sambucy, Neoen Australia’s Managing Director, said. “It was made possible through the support of South Australian Government, and of the Australian Government via ARENA and CEFC. In pioneering the delivery of grid-scale inertia, Neoen continues to lead the way in battery storage innovation, reinforcing its contribution and commitment to South Australia’s 100% renewable energy target.”
“The strong collaboration with Neoen and supporting partners to develop an inertia-enabled grid-scale battery demonstrates what can be achieved to support Australia’s once-in-a-century energy transformation,” Daniel Westerman, AEMO’s CEO, adds.
“The Hornsdale Power Reserve was revolutionary when we commissioned it back in 2017 and continues its pioneering role,” added Tom Koutsantonis, South Australian Minister for Energy and Mining. “It is leading the innovation of inverter-based technologies – paving the way for more, much needed large scale storage projects both in Australia and beyond. Expanding the capabilities of the Hornsdale Power Reserve by activating Virtual Machine Mode, a first for the world, further demonstrates South Australia’s commitment to global leadership in the adoption and integration of renewable energy to improve grid stability and energy reliability, while bringing power prices down for all South Australians.”
Naturally, not having a PR department and not being big into traditional PR, there was no comment from Tesla included in the press release. However, if you want to see other executive partners congratulating themselves, you do read their comments here.
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