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Central battery storage for the Darwin-Katherine grid

UPDATE 5/4/20: For months you've joined us and NT solar industry leaders in calling for central battery storage for the Darwin-Katherine grid. And today the NT Government delivered by approving procurement of a large-scale battery for the Darwin-Katherine grid.

A central battery storage system for the Darwin-Katherine grid would help provide reliable power to Territorians and facilitate renewable energy.

Critics claim solar energy is inconsistent due to cloud cover. But the reality is that all types of electricity generators – including gas and coal – can fluctuate or even fail. Frequency and voltage often fluctuate, the quality of gas supply (even air temperature changes) can cause gas turbines to change their output, and bad weather can impact conventional power plants or transmission lines.  

Energy storage in modern electricity grids stores energy when there is an excess of electricity generation, at other times drawing on that energy. Batteries can charge and discharge very quickly and the effect on the grid is to smooth out fluctuations. 

Grids are essentially “wobbly” but are stabilised through technology and as the cost of battery storage continues to fall, it simply makes good economic sense to install grid-scale battery storage on the Darwin-Katherine grid.  

In short, no matter what it is powered by – renewable energy or fossil fuels – the NT electricity system will benefit from storage. 

Where would central battery storage be located and how big would it be?

Detailed static and dynamic modeling of the Darwin-Katherine grid should determine where to locate centralised battery storage. It could result in a spread of locations for the infrastructure across a number of substations or power stations.

The Territory's main electricity generator, Territory Generation, stated in their last Statement of Corporate Intent they have already been exploring battery energy storage systems for the Darwin-Katherine grid. According to Renew Economy, Territory Generation issued a tender for a battery back in 2017 and remains in talks with the government over the project. Former CEO Tim Duignan has said the battery could potentially be sized at around 35MW and with 35 minutes of storage. They need to be supported in this endeavor. 

Duignan told Renew Economy, "The gas generators are struggling to cope, and the battery would be sized for 35 minutes storage because that is the time it takes for the gas generators to react. It would operate in much the same way as the Alinta battery next to the Mt Newman gas generators in the Pilbara, which has saved fuel costs and lifted reliability.” Centralised battery storage would help ease the constraints on the link between Darwin and Katherine.

How will this create Territorian jobs and support Territorian businesses?

Installing battery storage on the Darwin-Katherine grid means more solar energy can be added to the grid – and that means more solar jobs and more business for NT solar companies. More solar energy also lowers NT electricity costs, which in turn drives economic development and job growth. 

How can this be paid for? 

Any generator (renewable energy or fossil fuels) that requires help from the battery to maintain stable electricity supply will pay for this service. The small additional cost is simply added to the base generation cost as with any generator system. Because solar is so cheap it can easily pay for this stability support.

What are other states and territories doing? 

In other parts of the country, grid-scale battery and other forms of storage are proving their mettle. For example, the big Tesla battery in South Australia already beat fossil fuel generators to the task of supplying extra power to the grid when a coal plant failed in Victoria and is constantly clipping peak power demand spikes. 

A central battery would complement other methods of introducing flexibility and resultant resilience into the system. Cost-effective demand-side management is one such technology. It's exciting to see so many energy storage technologies at different scales being rolled out in other states: from pumped hydro to flywheels, molten salt thermal energy storage to grid-scale chemical batteries such as flow batteries. For private households, installing electro-chemical battery systems like the Tesla Powerwall are also becoming more popular. 

Learn more about:

Alinta (Pilbara region of West Australia)

  • Predicted five-year payback 
  • Has reduced the need for back-up (yes, even fossil fuel generators need back-up), slashed fuel costs and increased reliability
  • Speed of reaction and strength meant it could hold the grid together if the main turbine or turbine tripped, significantly reducing outages

Hornsdale (South Australia)

  • The "Tesla big battery" - at 100MW and 129MWh remains the biggest lithium-ion battery in the world
  • Built in less than 100 days in late 2017
  • Money it saved consumers in 2019 jumped to $116 million, from $40 million in 2018
  • The state government has only had to inject $4 million a year for 10 years under its underwriting agreement for the battery, and as financial results have shown, the $96 million total investment is also delivering a handsome return for its owners, Neoen Australia

Learn more about our 10-point plan to repower the NT.