Works begin on Darwin big battery, in first step to rid gas from NT grid

Construction is underway on the Northern Territory’s first big battery, a 35MW energy storage system that will bolster the Darwin to Katherine Electricity grid as it slowly shifts away from costly and polluting gas and towards 50 per cent renewables by 2030.

NT chief minister Natasha Fyfe said on Monday that the beginning of works on the Darwin big battery marked a “huge step forward” for the Territory’s energy transition, with earthworks complete, foundations laid and in-ground services and culverts well underway.

Fyfe says the $45 million Darwin-Katherine Battery Energy Storage System (DK BESS) will – when completed, in 2023 – form “the backbone” of the Territory’s biggest electricity network, which provides energy to 150,000 customers. It will have one hour of storage, as most of its focus will be on grid stability.

As well as helping to wean it off gas, Fyfe says the DK BESS will also cement the NT as “the solar capital of Australia,” by soaking up daytime surplus generation and unlocking further capacity for households, businesses and industry to install rooftop PV.

It might also allow for the four utility-scale solar farms in the Darwin region, some of which have been built more than two years ago, to be finally switched on.

The NT government announced its plan to build the big battery in early 2020, at that time committing to a $30 million spend on the facility, reasoning that it would generate savings of around $6.4 million a year and deliver a pay-back of less than five years.

The overall spend on the big battery, which is being built by Hitachi, has since gone up to $45 million, but the expected annual cost savings have also increased to around $9.8 million per year, keeping the promise of a five-year payback period intact.

For more information about the battery, please read: Hitachi wins Darwin big battery tender, in major step towards solar-only grid

In any case, the extra $15 million has been covered by a federal government grant awarded by former energy minister Angus Taylor in May of 2021, as part of a bilateral deal with the NT government.

“Construction of the Darwin-Katherine BESS is a huge step forward in our plan for 50% renewables by 2030,” said NT minister for renewables and energy, Selena Uibo, in a statement on Monday.

“Our electricity will be more reliable and stable, whilst maintaining affordability for Territorians.

“Our future is renewables,” added Uibo. “This is why we are investing now in the BESS and hydrogen powered generators so we can have clean and efficient energy to help reach our renewables and net zero emission targets.”

Territory Generation CEO Gerhard Laubscher says the Darwin-Katherine battery will also be key to unlocking flexibility in the Territory’s generation fleet to better manage the increasing impacts of solar on the system.

As RenewEconomy reported here in December, when Hitachi was awarded the job to deliver the big battery, the NT 50% renewables target will have to be met by solar, which means solar will need to deliver all, or nearly all, of the grid’s daytime electricity needs.

To achieve that outcome, and not have gas generators running in the back-ground, requires hi-spec battery storage inverter technology that can operate in “grid forming mode” or as “virtual synchronous machines”.

The Hitachi battery will have this capability – as others already do in the Australia’s main grid – but it means that with another one or two similarly capable batteries, the Darwin-Katherine grid could be the first of its size in the world to operate on solar alone, with batteries rather than fossil fuels in support.

“This technology unlocks the last mile of renewables and, without it or synchronous condensers, you need to keep a minimum number of thermal generation online,” Hitachi’s Stephen Sproull told RenewEconomy.

“We saw how the installation of synchronous condensers in SA unlocked more renewables and it is the same with grid forming BESS in the NT.”

The Darwin battery will likely be dwarfed by the up to 42GWh of battery storage planned to support the up to 20GW of large scale solar proposed by Sun Cable to supply both Singapore and new green industry in the Darwin region.

See also RenewEconomy’s Big Battery Storage Map of Australia