New South Wales’ electricity system will be at risk if the government dilutes its own planning for long-duration electricity storage, the Australian Solar Thermal Research Institute (ASTRI) and the Australian Solar Thermal Energy Association (AUSTELA) have warned in a submission paper.
NSW’s Department of Climate Change, Energy, the Environment and Water is considering changing its definition of long duration storage from eight hours to four hours to help meet legislated targets to have 2GW at 16GWh of storage by 2030.
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ASTRI and AUSTELA have expressed concern that the change would disincentivise the construction of 12-hour-plus storage technologies, which are critical to ensuring the reliability and affordability of NSW’s electricity system as coal is phased out.
ASTRI and AUSTELA advocate consideration of concentrated solar thermal power and storage (CSP) systems, where mirrors capture the sun’s heat and store it in molten salt. The stored heat can then be used, on demand, as required to drive a turbine which generates power, typically for around 15 hours but up to 24 hours in some formats.
ASTRI director Dominic Zaal said his organisation and AUSTELA had made a joint submission to the department expressing caution against the proposal to redefine long-duration storage because of the risk it posed to the system, and because changing the definition of LDS would not resolve the challenges that NSW is facing.
“The problem for New South Wales is that in the next decade, three of the four remaining coal-fired power stations will close, and that removes around 70% of the system’s capacity,” he said.
“Coal generators cover the overnight electricity market and they are the safety net for renewables’ reliability events. When you build renewable storage to replace coal, four-hour battery systems are not enough and do not resolve the issue.”
Zaal said the shift in focus away from long-duration intraday storage to short duration battery storage was a false economy.
“While it might help to meet a short-term target, it will ultimately end up costing consumers more because you end up with over investment in short duration storage, at the expense of the longer duration storage the system actually needs. In essence, you pay to defer the problem, but not to actually fix it.
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“The obvious renewable technologies to cover the retired coal assets in NSW are pumped-hydro and CSP.
“According to CSIRO’s Renewable Energy Storage Roadmap, they are the long-duration intraday storage options that are cheaper than battery at eight hours, and they have between 12 and 24 hours of storage. They also produce power from synchronous/turbine technology, meaning solar thermal and pumped-hydro offer stability services to the system operator.”
