A new study published this week by the Australian National University (ANU) claims that pumped hydro storage could be used to help build a secure and cheap Australian electricity grid with 100% renewable energy sources. Specifically, the 100% renewable energy grid would rely primarily on wind and solar PV technology, and supported by off-river pumped hydro storage.
Lead researcher Professor Andrew Blakers from ANU also believes that this system would eliminate the need for coal and gas-fired power.
“With Australia wrestling with how to secure its energy supply, we’ve found we can make the switch to affordable and reliable clean power,” said Blakers, with the ANU Research School of Engineering.
The scenario put forward in the report estimates wind and solar PV contributing 90% of annual electricity, together with existing hydroelectricity and biomass sources contributing the remaining 10%. The report depicted an energy mix based on widely spread wind and solar sources to take advantage of different weather systems. The energy balance between supply and demand is maintained by adding sufficient pumped hydro storage and high voltage transmission, as well as excess wind and solar PV capacity.
“We term the cost of these additions as the levelised cost of balancing (LCOB). LCOB plus the levelised cost of annual generation (LCOG), combine to give the levelised cost of electricity (LCOE),” the authors of the report write.
“Using 2016 prices prevailing in Australia, we estimate that LCOB is AU$28/MWh, LCOG is AU$65/MWh and LCOE is AU$93/MWh. This can be compared with the estimated LCOE from a new supercritical black coal power station in Australia of AU$80/MWh. Much of Australia’s coal power stations will need to be replaced over the next 15 years. LCOE of renewables is almost certain to decrease due to rapidly falling cost of wind and PV. With PV and wind in the price range of AU$50/MWh, the LCOE of a balanced 100% renewable electricity system is around AU$75/MWh.”
Interestingly, the report takes its figure for new supercritical black coal power stations from a report published in 2015 by CO2CRC — “the only company in Australia to have undertaken carbon capture and storage as an emissions reduction technology from end to end.” While the figures need not necessarily be called into question as a result of this, a more recent report published by Bloomberg New Energy Finance (BNEF) earlier this year showed that the Levelized Cost of Electricity (LCoE) of new ultra-supercritical coal-fired power in Australia currently sits somewhere between AUD$134-$203/MWh — compared to current LCoE for new build wind (AUD$61-$118/MWh), solar (AUD$78-$140/MWh), and combined-cycle gas (AUD$74-$90/MWh).
This serves only to further the underlying case of the ANU report, by decreasing the LCoE of wind and solar, and highlighting the gap between new-build coal and new-build renewables.
This is vitally important in Australia especially, considering that many coal-fired power plants around the country are set to reach the end of their operational lifespan in the next 15 years, and would need to be replaced regardless of environmental and climate concerns. This only serves to heighten the role that renewable energy can play in Australia’s energy mix, and increases the need for policy and business support for the development of the renewable energy industry in the country.
Researchers from ANU are also working to map potential short-term off-river pumped hydro energy storage (STORES) sites that could support a larger share of renewable energy in the grid. STORES sites are pairs of reservoirs, around 10 hectares each, which are separated by an altitude difference of a around 300 and 900 meters, in hilly terrain, and connected via a pipe with a pump and turbine. According to Dr Matthew Stocks from the ANU Research School of Engineering, STORES needs much less water than power generated from fossil fuel, and had a minimal impact on the environment because the water is recycled between small reservoirs.
“This hydro power doesn’t need a river and can go from zero to full power in minutes, providing an effective method to stabilise the grid,” he said.
“The water is pumped up from the low reservoir to the high reservoir when the sun shines and wind blows and electricity is abundant, and then the water can run down through the turbine at night and when electricity is expensive.”