Flexibility options in a 100% renewable grid for Australia

Flexibility options for operating technologies available in a power system can facilitate the large-scale integration of variable renewable sources such as wind and solar whilst maintaining firm generation. In prior work, contributions of different flexibility options in future net-zero electricity networks vary widely across regions and scenario assumptions. Here we simulate a competitive-bidding process for an energy-only electricity system at 1-hr intervals to assess multiple flexibility options for supply and storage – including biomass, hydropower, concentrating solar power (CSP), electrical energy storage (EES), pumped hydro energy storage (PHES) and hydrogen (H2). We examine systemic effects of competing flexibility options and compare their grid-integrated cost-effectiveness in a future Australian 100% renewable grid. Our simulations indicate a variety of constellations with coexisting technologies, including flexibility options at various penetrations depending on storage cost and design points. We reveal the potentially significant role of long-term storage technologies (with months-deep discharge durations) in Australia's future 100% renewable grid, enabling significant reductions in the installed capacity of wind and solar PV, and thus overall system cost.