Firming Technologies to Reach 100% Renewable Energy Production in Australia's National Electricity Market (NEM).

The article focuses on modeling Australia's National Electricity Market (NEM) to determine the optimal mix of firming technologies required to achieve 100% renewable energy production, primarily from variable renewable energy (VRE) sources such as wind and solar. It finds that while pumped hydro and battery storage can address short-term supply-demand mismatches, they are insufficient to cost-effectively manage prolonged "energy droughts" when renewable output is low; thus, some form of zero-emission fuel-based technology—most likely hydrogen-fueled open-cycle gas turbines (OCGTs)—will be necessary to ensure system reliability. The study uses a time sequential solver model to optimize capacity and dispatch over multiple years, concluding that a diverse portfolio including storage and renewable peaking plants minimizes costs and enhances reliability. Policy implications include scaling investment in zero-emission thermal plants, introducing mechanisms to increase clean fuel production in the gas network, and adjusting market designs—particularly price caps—to incentivize long-duration firming technologies without relying on subsidies for existing coal plants.