How sodium-sulfur batteries can help bridge the storage gap in the energy transition

April 8, 2024

Sodium-sulfur NAS

As Australia’s coal-fired power stations progressively close over the next 10-15 years, it will be critical to ensure that the grid has enough storage to balance variable supply from wind and solar.

The size of energy storage systems is described by two parameters:

(1) the maximum power they can discharge into the grid; and

(2) their storage duration i.e. how long they can keep discharging at maximum power.

To date, the rollout of utility-scale battery storage in Australia has been dominated by lithium-ion batteries with short storage durations of two-hours or less. Batteries have big advantages in that they are modular, can be rolled out relatively quickly, and are not dependent on unique geographic formations.

However, long duration energy storage (LDES) has an important role to play in derisking the clean energy transition by protecting against prolonged droughts in wind/solar output. The federal government as well as the Queensland state government have both committed significant resources to pumped hydro projects. For example, Snowy 2.0 is expected to have almost a week’s worth of storage while Borumba Pumped Hydro could have up to 24 hours. However, these pumped hydro projects are incredibly complex and have long lead times. There is an opportunity for alternative battery chemistries, such as sodium-sulfur, to help bridge the gap between lithium-ion batteries and pumped hydro by providing medium-to-long duration storage within a much shorter lead time.

Energy Synapse sat down with Ross Sang, an expert in sodium-sulfur batteries, to get his insights on how this technology can help Australia transition to clean energy. Ross is National Business Manager, Energy Storage at BASF Australia (provider of NAS® batteries). BASF has recently been announced as a successful proponent in a battery trial designed to boost reliable renewable supply for regional WA.

Ross Sang BAS sodium-sulfur NAS battery

Ross Sang, BASF Australia

Can you tell us more about sodium-sulfur (NaS) battery technology and how it has been rolled out internationally?

NAS® batteries were the first commercialised battery energy storage technology designed for large-scale stationary application. They have a successful track record over more than 20 years and have been deployed at more than 250 locations worldwide with a total power exceeding 720 MW and a storage capacity of approximately 5.0 GWh. It may be a surprise to many, that the largest battery in the world in 2016 was a 50 MW / 300 MWh NAS® battery that was constructed in 6 months in Japan and remains operational today.

What is the sweet spot for sodium-sulfur batteries in an Australian context?

The primary role of NAS® batteries in the energy transition is to support decarbonisation through energy arbitrage. This involves shifting large amounts of renewable energy to periods of low generation on a daily basis. The NAS® batteries large energy capacity and optimal discharge duration of 6-8 hours can support the displacement of fossil fuels in microgrids, industrial processes, and power generation and can be scaled up to hundreds of megawatts to support Australia’s path to its renewable energy targets on the grid.

What do you see as the main advantages of NaS batteries compared with other long duration storage technologies?

NAS® batteries operate at high temperature so they are not affected by ambient temperatures and do not require air-conditioning or a fire suppression system. This means they are particularly well suited to many arduous environments and have a very predictable degradation. This was well proven last year, whilst the first Australian NAS® battery was being commissioned at 45°C in Western Australia, another system was coincidentally being commissioned in South Korea at an ambient temperature of -18°C.

Furthermore, these attributes along with a number of others, mean the NAS® batteries have low maintenance requirements and the containerised design enables fast and simplified installation on site leading to a much shorter construction time compared to other LDES technologies.

Are there any unique considerations that project developers and EPCs need to take into account if they are thinking about using NaS technology in their projects?

As mentioned, the standard 20ft containerised form factor of NAS® batteries allows straightforward installation at the project site, and as the containers can be stacked, the footprint is relatively small. Due to the C-rate of 1/6, NAS® batteries are suited to applications of 6 hours or more and when paired with suitable Power Conversion Systems the NAS® batteries impressive response rate of <10ms can be utilised to perform advanced grid stabilisation services.

Capacity Investment Scheme (CIS) Consultation Paper – high level summary

August 7, 2023

The Australian Government has released a public consultation paper seeking feedback on the design of the Capacity Investment Scheme (CIS). Responses are due by 31 August 2023.

We have put together a high-level summary of key elements of the scheme in this article.

Objective of the Capacity Investment Scheme

The CIS aims to encourage new investment in clean dispatchable capacity, support reliability, and reduce the risk of price shocks in Australia’s rapidly changing energy market.

The CIS expects to bring forward at least $10 billion of new investment and 6 GW of clean dispatchable capacity by 2030.

How the CIS works

There will be a series of competitive tenders seeking bids for clean generation and storage projects to fill expected reliability gaps.

Projects that are successful in the tender process will be offered long-term Commonwealth underwriting agreements for an agreed revenue “floor” and “ceiling” (see Figure). If the project earns more revenue than the “net revenue ceiling”, the owner will pay the Commonwealth an agreed percentage of revenue above the revenue ceiling. In contrast, if the project earns less revenue than the “net revenue floor”, the Commonwealth will pay the project owner an agreed percentage of the shortfall below the revenue floor (but not below zero).

Capacity investment scheme

This design is intended to increase investor certainty, while still giving project proponents flexibility in how they participate in wholesale electricity and contract markets.

Geographic coverage

The Capacity Investment Scheme is expected to be a national scheme covering the National Electricity Market (NEM) on Australia’s eastern seaboard as well as Western Australia’s Wholesale Electricity Market (WEM). The Australian Government is also exploring options to support capacity in the Darwin-Katherine Electricity System (DKIS).

Eligible projects

It is expected that projects will need to meet the following eligibility criteria:

– Produce zero Scope 1 emissions. Coal and gas projects (including blended fuel projects) will not be eligible. Note that storage projects that charge from the grid are considered to have zero scope 1 emissions and thus are eligible.

– Have a capacity of at least 30 MW (this requirement might be reduced in the WEM).

– Demonstrate that the project can contribute to system reliability. Standalone wind or solar PV projects will not be eligible due to their variability. However, VRE + storage hybrids are expected to be eligible. Demand response projects may also be eligible if they are capable of reducing demand for at least four hours. Storage projects are expected to have flexibility in how they bid in the CIS. For example, a 100 MW/200 MWh battery may bid as a 2-hour 100 MW dispatchable asset or a 4-hour 50 MW dispatchable asset.

– Be registered with AEMO and intend to participate in the central dispatch process.

– Use established/proven technology.

– Achieve financial close from 8 December 2022 onwards. Projects that have achieved financial close before 8 December 2022 will be not be eligible.

– Projects that are already, or will be, in receipt of revenue support from Commonwealth or state and territory governments will not be eligible for the CIS tenders. LGCs, ARENA grants, CEFC are all ok and will not impact eligibility.

– Projects can be privately or publicly owned.

Expected timeframes for CIS tenders

Tenders for the Capacity Investment Scheme are expected to be progressively rolled out from 2023 through to 2027 to meet reliability needs between FY2026 and FY2030. The reliability targets are expected to be expressed in terms of capacity (MW), medium storage (4-hour) equivalents.

The first phase of the CIS is expected to involve:

Partnership with NSW Electricity Infrastructure Roadmap announced on 29 June 2023. This will involve Commonwealth support for up to 550 MW of firmed capacity, in addition to 380 MW already committed by NSW.

– South Australia / Victoria tender. Tender arrangements will be announced by October 2023.

Further details on the national roll out of the CIS are expected to be outlined by the end of 2023.

Feel free to contact us if you have any further questions.


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