|Fig. 1: Starfish Hill wind farm in South Australia. (Source: Wikimedia Commons)|
Around half of South Australia's power generation capacity now comes from wind and solar farms, an example of which can be seen in Fig. 1.  The share of the energy mix by these renewable energy sources is likely to continue increasing as the Australian government advances climate policy subsidies and a market design that imposes renewable intermittency costs on the remainder of the grid.  As a result, the Australian state is proving a world leader in the rapid rise of renewable penetration into an energy grid, especially for markets with limited or unreliable interconnections into neighbouring systems. 
The transition to renewable energy in South Australia has not gone as smoothly as planned. The green energy subsidies provided by the government allow wind and solar farms to underbid coal and gas into the wholesale electricity market, significantly reducing the economic value of coal and gas power generation.  This has lead to the closure of all coal generators and a major reduction in gas power utilization in the state.  With fewer traditional fossil fuel generators in the market, South Australia has less capacity to generate energy on demand. This can cause major issues when demand is high and the wind isn't blowing or the sun isnt shining. 
Demand for power is particularly high during the summer months, when temperatures in South Australia frequently spike to greater than 40°C.  To offset this, the Australian Energy Market Operator (AEMO) directs power companies in South Australia to begin switching off customer power supplies as part of a technique called load shedding.  Load shedding occurs because the electrical grid always has to remain in balance between supply and demand.  If there is no ancillary energy supply available, the authorities have no choice but to reduce demand by shutting customers off.  If demand is not decreased, the entire system can fail, causing statewide blackouts like the one that occurred in September of 2016. 
|Fig. 2: Tesla PowerPack (Source: Wikimedia Commons)|
In the aftermath of the 2016 blackout and frequent load shedding, the South Australian government prepared a $550 million plan designed to stabilize the energy grid.  The plan asked for expressions of interest from the private sector to construct and operate a large, grid-connected battery that would stabilize energy supply during periods of high demand.  Of the 91 private sector applicants, Tesla was awarded the contract after CEO Elon Musk guaranteed the battery would be completed within 100 days. 
On December 1st, 2016, the world's largest lithium-ion battery was officially connected to the Australian energy grid by Tesla at the Hornsdale Wind Farm in South Australia, following through on the company's 100 day guarantee.  The mega-battery, composed of numerous Tesla Powerpack modules (Fig. 2), was constructed in partnership with state government and Neoen, the French renewable energy company that owns the wind farm.  The battery has a total generation capacity of 100 megawatts, and 129 megawatt-hours of energy storage, which Tesla and Neon describe as capable of powering 50,000 homes and providing 1 hour and 18 minutes of storage. 
The South Australian battery is truly a historic moment for South Australia and for Australia's future energy security.  Furthermore, it represents a significant step toward solving the instability issues that are inherent to many of the most promising renewable energy sources, simplifying the path toward a 100% green energy future.
© Scott Buttinger. The author warrants that the work is the author's own and that Stanford University provided no input other than typesetting and referencing guidelines. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
 S. Kavonic, "Making the Transition: What South Australia Can Teach Us About Switching On To Renewables," Forbes, 27 Aug 17.
 N. Harmsen, "South Australia's Power Woes Expose Deeper Problems With Nation's Energy Security," ABC News Australia, 8 Mar 17.
 N. Harmsen, "SA Power: What Is Load Shedding and Why Is It Happening?" ABC News Australia, 9 Feb 17.
 N. Harmsen, "Tesla to Supply World's Biggest Battery For SA, But What Is It and How Will It Work?," ABC News Australia, 7 Jul 17.
 D. McConnell, "SA's Battery Is Massive, But It Can Do Much More Than Store Energy," ABC News Australia, 5 Dec 17.