The next challenge for energy storage: How do we firm the grid overnight?

Energy pundits are exploring solutions to cover 8 to 12-hour periods. This is the Holy Grail of energy storage.

A year ago, the lack of battery and storage assets to manage “renewable droughts” topped energy transmission experts list of things going wrong with Australia’s energy transition.

Since then, the number of battery projects has skyrocketed. Nearly eight gigawatts of combined capacity are in the “committed” or “anticipated” phase, according to AEMO’s criteria, meaning they will proceed or are likely to.

On top of this, an eyewatering 74 gigawatts of battery storage projects have been publicly announced, according to AEMO’s abacus.

Engie is one of them, commissioning the world-largest Battery Energy Storage System (BESS) at Hazelwood last year, to store the equivalent of one hour’s electricity generated by the solar systems installed on the roofs of 30,000 homes in the state of Victoria.

At the unveiling, Engie’s Executive Vice President in charge of Flexible Generation and Retail activities, Sebastien Arbola, talked up batteries’ potential to boost the development of renewables by bridging the gap between demand and intermittent supply.

This function is what Imperial College London researcher Oliver Schmidt calls the first of four phases of deployment of energy storage.

A steady 50Hz frequency

“The first phase which many states are going through, or have gone through, is very short duration - one hour – to firm the grid on a second-by-second basis to manage the frequency fluctuations that occur with more renewables in the grid,” explains Schmidt.

Daily peaks

The second phase is for “peaking” – batteries with 2-6 hour duration to store excess electricity generated when the wind is blowing and the sun shining, for dispatch to manage daily peaks. These peaks, which become more pronounced the more solar you have, are often country and event specific. In Germany, for example, Schmidt says the daily peak occurs during the day when heavy industry is running at full tilt, while in the United Kingdom, it’s more likely to happen in the evening when people crank up their home appliances.

Energy Storage Industries Asia Pacific Managing Director, Stuart Parry says getting sufficient energy storage in the grid is critical to unleashing the next wave of renewable generation projects.

“Without some degree of firming, we’re not going to see that next wave of renewable development to meet our [national] 2035-2050 targets,” Parry says.

The Holy Grail of energy storage

To date, Parry says the focus has been on short duration storage to utilise cheaper energy, reduce prices, and cover positions for the traders, particularly in the retail world.

Now, the conversation has turned to firming the grid overnight using medium-duration storage solutions.

“As more [fossil-fuel] power stations come offline we’re seeing demand move. Last year people were talking about 6 hours, now they’re talking about 10 hours,” Parry says.

The integration of daytime solar and wind generation for use at night is the “Holy Grail of storage”, according to Schmidt.

“The third phase market is huge because you need lots of capacity to shift the solar generation to the evening – 8 to 12 hours,” he says.

Long duration trials

The last phase is long term and seasonal storage – weekly and monthly capacity - which is where technologies like hydrogen and flow batteries come into play.

Last month, the Albanese and Cook Governments announced they are funding trials of long-duration batteries to help Australians living in off-grid communities store cheaper, cleaner solar energy.

With $2.85 million each from the Australian Renewable Energy Agency (ARENA) and the WA government, regional energy provider Horizon Power will pilot two new battery technologies in remote communities powered by regional microgrids. The trials will establish new forms of energy storage and help Horizon Power diversify long-duration battery solutions for extreme climates.

This follows Horizon Power’s purchase of a vanadium redox flow battery for a long duration energy storage trial in Kununurra, in the Kimberley.

“Horizon Power was an early adopter in battery energy storage, and for the past 15 years we have been exploring how energy storage can best be used to promote increased uptake of renewable energy across regional WA,” Horizon Power Chief Executive Officer, Stephanie Unwin, says.

“Our long duration energy storage (LDES) trials will provide key learnings around how the technology can be effectively integrated into our network and test their temperature resilience in regions with extreme weather conditions,” she says.

Schmidt points out that with more transmission and better interconnection between states, the need for energy storage diminishes. This will impact the economics of the 74 GW worth of proposed battery storage projects, as well as how many of them actually make it to fruition.

In terms of technology winners and losers in the energy storage wars, Schmidt says lithium has emerged the clear winner from the first two phases – short duration and peaking.

He believes that lithium can claim the lion’s share of the medium duration market, however Parry says the grid will require a mix of technologies, including flow batteries, which are a product of the University of NSW (which also gave the world the most commercially viable and efficient silicon solar cell technology, the Passivated Emitter and Rear Cell or PERC).

“Any single technology that says they are going to provide the panacea to all our issues is lying,” Parry says. “There’s going to be multiple chemistries in flow [batteries], there’s going to be new batteries developed, EVs will be providing demand response, whether people like it or not there will be some degree of gas, because when push comes to shove people don’t want their electricity to drop off.”

Three of the interviewees in this article (plus many more!) will be speaking in the Batteries and Energy Storage Stream of Australian Energy Week 2024 (13 June).

To access the detailed conference program, download the brochure here.