Australia has put into commercial operation, for the first time, a long-duration grid battery capable of discharging continuously for 8 hours. The battery is expected to ease supply-demand imbalances in renewable-heavy power grids by quickly storing surplus solar power during the day and supplying it for an extended period from evening into the night.

Electrek, an electric vehicle outlet, reported on Sept. 18 local time that German energy company RWE's Limondale battery energy storage system (BESS) has completed registration with the National Electricity Market in New South Wales and started operating.

The Limondale battery consists of 144 Tesla Megapacks and is rated at 50 MW and 400 MWh. It is located near Balranald in southwestern New South Wales and was built together with the existing Limondale solar power plant. It has entered commercial operation after receiving final operating approval from grid operator AEMO.

A key feature is a design that sets different outputs for charging and discharging. Limondale charges power at about 100 MW and discharges at 50 MW. The design increases charging speed and lowers discharge speed compared with typical grid batteries.

As a result, it can rapidly store surplus solar generation for about 4 hours during the day, then supply power for up to 8 hours from the evening peak into the night. The battery is intended to compensate for solar power's characteristic of surplus generation in the daytime and shortages after sunset.

Australia already operates large battery storage facilities, but equipment capable of long-hour discharge has been relatively rare. Early grid batteries mainly provided 1- to 2-hour duration, focusing on grid stabilisation and fast response, and 4-hour facilities have recently been expanding.

Limondale is an 8-hour long-duration storage system that focuses not only on storing renewable power but on shifting it to the hours when it is needed.

Policy support to expand long-duration storage was also applied during project development. Limondale was selected as the only winning project in the first long-duration storage tender held under New South Wales' Electricity Infrastructure Roadmap.

A structure was also applied under a long-term energy services agreement that guarantees a minimum level of revenue. The measure is intended to support investment and financing for large long-duration batteries. Two other 8-hour battery projects receiving the same institutional support are also moving through follow-on procedures.

RWE has stressed the Limondale project as an example of expanding long-duration energy storage from the early stages of the project. Katja Wünschel (카트야 뷘셸), chief executive of RWE Renewables Europe & Australia, said at the time of project approval that the investment decision and the signing of a supply contract for the Limondale BESS project were progress.

Tesla supplied Megapacks for the project. Beon Energy Solutions handled construction of auxiliary facilities for the plant.

Limondale also has significance in the expansion of Tesla's energy storage business. Tesla recently started operating a 500 MWh Megapack battery in Texas and is also pursuing a 1 GWh project in Britain. Limondale's structure focuses on shifting power by time of day rather than simply adding battery capacity. It absorbs relatively cheap renewable power during the day and supplies it from evening into the night when power demand rises.

As long-duration storage expands, it can use surplus power during hours of high solar output, helping to compensate for variability in renewable generation. Because batteries can be used when power supply is short, they are also cited as a means to reduce reliance on fossil-fuel generation.

The start-up of the Limondale battery shows that grid batteries in Australia are expanding from a focus on short-term grid stabilisation to storing and shifting renewable power for long durations. Whether follow-on 8-hour battery projects under way in New South Wales lead to actual commercial operation is expected to be a key point to watch in the long-duration energy storage market.