Eraring’s 3,160MWh battery shows how to turn a coal plant into a smart, AI-managed clean energy hub. Here’s why it matters and what businesses can copy.
Australia just approved a 3,160MWh battery at a coal plant that used to define the fossil-fuel era.
That single project at Eraring in New South Wales will be able to shift more clean electricity in one evening peak than many countries currently store on their entire grids. For anyone serious about green technology, this isn’t just another infrastructure headline — it’s a blueprint for how to retire coal without crashing reliability or profits.
This matters because businesses, investors and policymakers are all facing the same tension: how to phase out high-emissions assets while keeping the lights on and margins healthy. Big battery energy storage systems (BESS) like Eraring are becoming the preferred answer.
In the context of our Green Technology series, Eraring is where several threads converge: AI-driven energy management, long-duration storage, grid-forming inverters, and the transition of legacy fossil infrastructure into clean energy hubs. Here’s what actually matters about Origin Energy’s decision to pick Wärtsilä for all four stages of the project — and what you can learn from it if you’re planning or financing clean energy.
What Origin and Wärtsilä Are Really Building at Eraring
Eraring is being transformed from Australia’s largest coal plant (2,880MW) into the site of the country’s largest approved battery storage project by energy capacity: 3,160MWh of BESS.
Origin Energy, a major “gentailer” (generator + retailer), has now locked in Wärtsilä to deliver all four stages of the battery rollout at the Eraring site:
- Stage 1: 460MW / 920MWh (2-hour duration), construction started 2023
- Stage 2: 240MW / 1,030MWh, with grid-forming inverters, construction started October 2024
- Stage 3: ~700MWh, extending total site duration from 2 to 4 hours
- Stage 4: New appointment to reach a total 3,160MWh of capacity
By early 2027, once construction finishes, Eraring’s battery will be able to:
- Store enough energy to cover several hours of evening peak demand
- Provide fast frequency and voltage support
- Backstop the grid as coal units retire
The reality? This is less about one project and more about a model: use existing grid connections, land, and transmission from coal plants, then overlay them with smart, large-scale energy storage.
Why Coal Closures Now Depend on Big Batteries
The Eraring story captures the core challenge of the energy transition: coal is being priced out by renewables and storage, but system operators still worry about reliability.
Here’s the sequence:
- Eraring, at 2,880MW, has been Australia’s largest single-site coal generator.
- Origin originally planned to close it early, moving the retirement date forward from 2032 to 2025, arguing that “cleaner and lower-cost generation, including solar, wind and batteries,” made coal uncompetitive in the National Electricity Market (NEM).
- The Australian Energy Market Operator (AEMO) pushed back, warning of capacity shortfalls if Eraring shut too soon.
- In 2024, the New South Wales government agreed to a temporary extension to August 2027, under conditions including capped recoverable losses and payback of profits.
So why invest in a huge BESS there instead of just running coal longer?
Because batteries solve three problems at once:
- Reliability – They can respond in milliseconds, providing firm capacity and grid services when demand spikes or wind/solar output drops.
- Economics – As battery costs keep falling and solar/wind keep undercutting coal on marginal cost, storage turns volatility into an opportunity: buy energy when it’s cheap, sell when it’s scarce.
- Climate and policy risk – Building new coal is politically radioactive and financially risky. Converting coal sites into clean energy hubs is far easier to defend.
If you’re an asset owner sitting on aging fossil plants, Eraring is a loud signal: the fastest path to a credible transition plan is often battery storage plus flexible renewables, not squeezing another decade out of the boilers.
The Technology Stack: Quantum BESS, Grid-Forming Inverters and AI
The hardware at Eraring is only half the story. The real value sits in the software and controls.
Wärtsilä’s Quantum BESS and GEMS platform
Wärtsilä is supplying its Quantum series large-scale BESS units at Eraring, paired with its GEMS Digital Energy Platform for energy management and control.
In practice, that means:
GEMSacts as the “brain” of the site, optimising charge/discharge decisions in real time.- It coordinates multiple battery stages as a single virtual asset, even though they’re built in phases.
- It can stack revenue and value streams: energy arbitrage, frequency control ancillary services, fast frequency response, and potentially system strength services.
This is where AI and advanced analytics come in. Modern EMS platforms use forecasting and optimisation algorithms to:
- Predict demand and renewable output
- Price different services in real time
- Decide whether it’s more profitable (or more valuable for reliability) to hold back energy for later or dispatch now
I’ve found that this is exactly where many projects succeed or fail. Two batteries with identical hardware can earn very different returns depending on the quality of their software stack and operational strategy.
Grid-forming inverters: making batteries behave like big spinning machines
Stage 2 and the Mortlake BESS project highlight another critical trend: grid-forming inverters.
Traditional inverters are “grid-following” — they rely on existing grid signals from big spinning machines (coal, gas, hydro) to synchronise. As those machines retire, grids risk losing inertia and strength.
Grid-forming inverters flip that dynamic:
- They create stable voltage and frequency references.
- They can operate as “virtual synchronous machines,” providing inertia and fault current.
- They allow high-renewables grids to stay stable even with very low fossil generation.
Australia’s National Electricity Market is already a global testbed for this. AEMO has identified nearly a hundred grid-forming battery projects in the pipeline. Eraring and Mortlake are part of this shift: batteries are no longer just energy-shifters; they’re becoming core grid stability assets.
For green technology investors, that means batteries aren’t competing only in the energy market. They’re becoming infrastructure that underpins system security, which can justify longer contracts and more bankable revenue structures.
How Eraring Fits into Australia’s GWh-Scale Storage Wave
Eraring doesn’t stand alone. It’s one node in a rapidly growing ecosystem of large-scale storage and advanced green technology across Australia.
A few useful reference points:
- Waratah Super Battery (NSW): 850MW / 1,680MWh. Larger in power, smaller in energy than Eraring. Designed as a “shock absorber” for the grid, though recently delayed by a transformer failure during testing.
- Melbourne Renewable Energy Hub (Victoria): 600MW / 1.6GWh BESS now in commercial operation.
- Quinbrook’s proposed GDSA Energy Hub (Queensland): 780MW / 6,240MWh (8-hour duration) paired with gas turbines — a clear signal that long-duration storage is the next frontier.
- Western Australia’s 500MWh vanadium flow initiative: A pivot to alternative chemistries for long-duration use cases beyond lithium-ion.
The pattern is clear:
- Short-to-mid duration lithium-ion BESS (2–4 hours) are being deployed quickly to handle evening peaks and stability.
- Longer-duration solutions (6–8 hours and beyond) are moving from concept to serious development, especially where industrial loads or weak grids need deep decarbonisation.
From a strategic perspective, Eraring is a 4-hour class battery, which is currently the sweet spot for replacing coal peaker output and supporting solar-rich grids. It’s big enough to matter but still uses commercially mature, financeable technology.
What Businesses and Investors Can Learn from Eraring
You don’t need a 3GWh coal-site battery to apply these lessons. The same logic scales down to industrial sites, commercial portfolios, and regional utilities.
1. Treat grid constraints as an asset, not a barrier
Origin’s core advantage at Eraring isn’t only the battery; it’s the existing grid connection and transmission built for 2,880MW of coal. That infrastructure is incredibly expensive and slow to duplicate.
If you:
- Own or access brownfield sites
- Have legacy infrastructure with spare capacity
- Face connection delays on new renewables
…then repowering or “co-siting” storage can be far faster and cheaper than greenfield builds.
2. Make software and controls part of your investment thesis
Hardware is commoditising. Controls and optimisation are not.
When you evaluate a BESS or broader green technology project, ask very specific questions:
- Which EMS or AI platform is controlling dispatch?
- Can it co-optimise multiple markets and services?
- How does it handle forecasting, and what’s the track record in similar markets?
- Is the system designed to support grid-forming or advanced services as future revenue streams?
The difference in project value between “basic arbitrage plus a bit of frequency control” and “fully stacked, AI-optimised multi-service operations” is often 30–50% in annual revenue.
3. Don’t separate decarbonisation from reliability
Most companies still think in a false trade-off: either they decarbonise or they stay reliable. Eraring demonstrates the opposite: battery storage and green technology can improve system resilience while cutting emissions.
For corporate energy users, that means pairing:
- On-site or contracted renewables (solar, wind)
- BESS or other storage
- Smart controls for load shifting and demand response
This is how you move toward 24/7 clean power for operations without exposing the business to price spikes or outages.
Where Green Technology Goes Next After Eraring
Eraring is a snapshot of where green technology stands as we close out 2025: large-scale, AI-managed batteries stepping into roles that coal once monopolised.
As we move into 2026, three trends will define the next wave:
- From megawatts to megawatt-hours – Power ratings grab headlines, but duration wins the transition. Expect more 4–8 hour projects and more experimentation with long-duration chemistries.
- AI-native energy systems – Energy management systems like GEMS will become more autonomous, using AI to optimise at millisecond-to-multi-day horizons across portfolios, not just single assets.
- Repowering the fossil fleet – The most credible transition plans will reuse coal and gas sites as anchors for storage, renewables, hydrogen, or hybrids — just as Origin is doing at Eraring and Mortlake.
If you’re planning your own green technology strategy — whether as a utility, corporate, or investor — use Eraring as a checklist:
- Are you turning legacy liabilities into clean energy hubs?
- Are you designing storage around both energy and grid services?
- Are you treating software and AI as central infrastructure, not an afterthought?
The companies that answer “yes” to those questions now won’t just meet net zero targets; they’ll own the assets that keep increasingly renewable grids stable and profitable.
Interested in how AI, storage and renewables fit into your transition plan? Start by mapping where your existing infrastructure, loads, and contracts could support a battery or smart energy system. From there, the Eraring model becomes surprisingly replicable.