Sun Cable plans Darwin big battery, precursor to world’s biggest solar and storage project

The Sun Cable consortium has unveiled plans for a substantial big battery in Darwin as a precursor to its broader plans to build the world’s large solar and storage project as part of a $20 billion to export Australia’s “sunshine” to Singapore and other south east Asia countries.

The 100MW/200MWh battery proposed for Middle Arm, on the outskirts of Darwin and close to its massive LNG export facilities is considered a “stand-alone” project, but will likely form part of the bigger solar and storage plans if the investment case is made.

The Middle Arm battery is one of at least two likely big batteries proposed for the Darwin-Katherine grid as it deals with a big increase in solar facilities, both behind the meter and large scale.

The state owned Territory Generation is also proposing a battery has has finally won the support of the NT government, to help both absorb the excess power and variability from the rooftop solar resources, and to accelerate solar’s deployment, and also as a cheaper option to the massive amounts of spinning reserve.

Sun Cable says its proposed battery does not impede on those plans, although it will require a change to the NT’s regulatory regime, which currently make it difficult for third parties to operate such projects.

“There is an absolute case for big battery to be installed,” Sun Cable CEO David griffin told RenewEconomy. “It would deliver a lot of value. It still needs modifications to regulations up there to make it work… because it not clear that the owner of the battery can be paid.”

Griffin described the Middle Arm battery as a “stand-alone” project, but if the broader Sun Cable vision went ahead it would certainly form part of those plans.

Its submission to the territory’s Environment Protection Authority says the Middle Arm battery will “provide lower cost electricity grid services and replace a portion of gas fired spinning reserve, to reduce the cost of electricity services for the Darwin Katherine Integrated System.”

It will also reduce greenhouse gas emissions through the reduced spinning reserve requirement and the increased operating efficiency of existing gas-fired power generators. The big battery at Newman in the Pilbara has achieved similar cost reductions and increased reliability in the grid that supplies some of the country’s biggest iron ore mines.

Sun Cable proposes to build 10GW of large scale solar, along with between 22-30 gigawatt hours of battery storage, and lay a cable from Darwin to Singapore, where it could account for up to one third of the country’s electricity needs.

The battery storage will be likely located in three locations – at the solar plant itself, where it will store capacity to be exported at night, and at the Darwin and Singapore ends of the proposed cable, where the batteries will supply FCAS and other important grid services to keep the supply secure.

That will require up to 600MW of battery storate in Singapore, and “several hundred” megawatts of battery storage in Darwin, with the exact configuration yet to be decided.

The sub-sea assessment, and the detailed design options, are being funded by Australian billionaires Mike Cannon-Brookes and Andrew Forrest, among others. The plans for the Darwin big battery will likely be confirmed early next year, although a final investment decision on the broader Sun Cable project is still a few years away.

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