Australia’s transition to renewables is gathering speed, but there’s a looming problem with storage. We will need much more long-duration storage to get us through the night, once the coal and fossil gas exit the system.
We also need to find new and better ways to create heat for industrial processes. Renewables can supply much of that heat during the day, but energy storage will be required to meet the industry’s night-time heat needs.
Solar thermal technology has the potential to provide both long-duration storage and industrial heat, but it has been largely overlooked in the Australian context. That is about to change.
the CSIRO Renewable Energy Storage Roadmap identifying a mix of technologies will be required, across sectors, to meet Australia’s energy storage needs, particularly at night. Solar thermal will be an important part of the mix.
Batteries alone won’t cut it. They’re good for short-duration storage, ranging from just minutes to an hour or two. But you’d need an awful lot of them, at enormous cost, to cover 8-12 hours. Solar thermal becomes cost-effective for long-duration storage at scale, and brings other benefits too.
Read more: Australia’s energy market operator is worried about the grid’s reliability. But should it be?
Introducing thermal energy storage
The Australian Energy Market Operator (AEMO) identified storage of four to 12 hours’ duration as “the most pressing utility-scale need in the next decade”. That’s what’s required “to manage stronger daily variations in solar and wind output, and to meet consumer demand, also during more extreme days, as coal capacity declines”.
Most people know about lithium-ion battery (chemical) storage and pumped hydro (mechanical) storage. However, thermal energy storage is not well understood or recognized. This is partly due to perceived costs and engineering challenges. However, as concentrated solar thermal plants are built all over the world – 30 are being developed in China alone – the knowledge base is growing.
More than 80% of Australia’s total energy use involves a thermal process:
- combustion of coal and gas for electricity
- combustion of fuels for transportation
- combustion of fuels for industrial process heat.
A large proportion of these existing fossil-fuel thermal processes can be met with renewable thermal energy storage.