Eos just raised over US$1B to scale US-made zinc long-duration batteries. Here’s why that bet matters for grid storage, investors, and green technology.
Most people glance at a headline like “US$1 billion financing” and think it’s just another big number. But when that money is going into long-duration, non-lithium batteries manufactured in the US, it’s a real signal of where green technology is heading next.
Eos Energy Enterprises has just closed financing transactions totaling more than US$1 billion, doubled down on US manufacturing, and staked its future on zinc-based long-duration energy storage. For anyone building or investing in clean energy projects, this isn’t just corporate news—it’s a roadmap for what the next decade of the grid could look like.
This matters because long-duration energy storage (LDES) is the missing piece between cheap renewables and a reliable, decarbonized power system. And it’s also where AI-driven grid optimization, domestic manufacturing, and climate policy all start to intersect.
In this article, I’ll unpack what Eos actually did, why zinc batteries are getting so much attention, and how this shift affects developers, utilities, investors, and anyone serious about green technology.
What Eos Just Did: The Short Version
Eos Energy raised and reshaped over US$1 billion in capital so it can scale US manufacturing of zinc-based long-duration battery systems and shore up its balance sheet.
Here’s the core of the transaction in plain English:
- US$600 million in new 1.75% convertible senior notes due 2031
- US$580.5 million net proceeds from those notes after discounts
- US$200 million of older, higher-cost 6.75% notes due 2030 repurchased
- About US$474 million in additional cash added to the balance sheet
- A separate US$458.2 million raised via common stock (35.86 million shares)
- Around US$80.2 million more from the exercise of ~7 million public warrants
The company also:
- Modified its loan agreement with the US Department of Energy (DOE), issuing warrants that let DOE share in potential equity upside
- Announced a US$352.9 million HQ relocation and expansion in Pennsylvania, firmly tying its growth story to US manufacturing
Financially, this gives Eos:
- A longer runway to reach large-scale production
- Lower overall financing costs versus their older debt
- The capital needed to fulfill a US$644.4 million order backlog (~2.5GWh) and chase a US$22.6 billion commercial pipeline (~91GWh)
Is Eos profitable yet? No. But it now has a credible path to try to get there.
Why Long-Duration Storage Is Getting So Much Money
The core bet behind this financing is simple: the grid needs more than 1–4 hours of storage if we’re serious about deep decarbonization.
Lithium-ion has been fantastic for 1–4 hour applications:
- Frequency regulation
- Peak shaving
- Solar firming
- Short-term capacity support
But as wind and solar share grows, different problems show up:
- Multi-hour ramps in the evening as solar drops
- Multi-day periods of low wind and sun
- Seasonal mismatches between generation and demand
This is where long-duration energy storage (LDES) comes in—systems that can store energy for 4–16+ hours cost-effectively.
Eos’s CEO Joe Mastrangelo calls this an “energy supercycle”—a period where LDES becomes core infrastructure rather than a niche add-on. I think he’s right. Every serious net-zero scenario—from utilities’ IRPs to academic models—leans heavily on some combination of:
- Long-duration electrochemical storage
- Hydrogen and other power-to-X options
- Demand flexibility and load shifting
The question isn’t if we’ll scale LDES. It’s which technologies will actually make it to bankable, gigawatt-scale deployment.
Zinc vs Lithium: What Eos Is Really Selling
Eos isn’t just selling batteries. It’s selling a different way to think about risk and value in storage.
How Eos’s Zinc Batteries Differ
Lithium-ion batteries typically offer 1–4 hours of storage and rely on:
- Critical minerals (lithium, nickel, cobalt depending on chemistry)
- Flammable organic electrolytes
- Complex thermal management and safety systems
Eos’s systems, based on its Znyth technology, use a hybrid aqueous zinc cathode with:
- 4–16+ hours of storage duration
- Non-flammable, water-based electrolyte
- Non-precious, widely available materials (zinc, manganese, etc.)
From a project and grid-planning standpoint, that translates into a few concrete advantages:
- Safety: Aqueous chemistries don’t carry the same thermal runaway risks as Li-ion, which can materially change permitting, siting, and insurance dynamics.
- Duration economics: Past a certain number of hours, Li-ion’s cost curve flattens badly. Zinc-based systems can be designed natively for 8, 10, 12+ hours.
- Supply chain resilience: Zinc is abundant and geographically diversified, and Eos is tying manufacturing to the US, lowering geopolitical and logistics risk.
But Can’t Lithium-Ion Do 8–12 Hours Too?
Here’s the honest answer: yes, technically—and some developers argue yes, economically in certain cases.
As Li-ion costs continue to fall and energy densities keep improving, 6–8 hour systems are starting to look feasible, especially where:
- Supply chains are secure
- Safety constraints are manageable
- Projects can stack enough revenue streams to justify the capex
However, relying entirely on Li-ion for everything creates concentration risk:
- Material price shocks
- Manufacturing bottlenecks
- Fire and safety concerns in dense urban or sensitive locations
My view: we’re going to need both. Li-ion will dominate short-duration and many mid-duration use cases. Zinc, flow batteries, and other alternatives will carve out serious share where:
- Long duration is non-negotiable
- Safety and siting are critical
- Domestic content and resilience are strategic priorities
Eos is trying to be the go-to option for that second category.
Why US Manufacturing Is the Real Story Here
The money is headline-worthy, but the direction of the money is what matters: toward US-based, long-duration battery manufacturing.
Eos is investing US$352.9 million to relocate and expand its headquarters and manufacturing in Pennsylvania. Combined with federal incentives and its DOE loan relationship, this aligns squarely with three major trends:
-
Energy security and resilience
Countries are realizing that energy transition technologies are strategic assets. Owning domestic capacity for critical components—like long-duration batteries—is now a policy objective, not just an economic nice-to-have. -
Policy-driven green technology growth
US federal programs, tax credits, and loans are explicitly pushing:- Domestic content
- Clean manufacturing
- Grid-scale storage to back up growing renewable portfolios
-
Jobs and local economic value
HQ relocation and factory build-outs mean:- Manufacturing and engineering jobs
- Local supply chain development
- Tax base growth for host regions
For developers and utilities, choosing US-made LDES solutions can also score points on:
- Domestic content requirements
- ESG metrics
- Community and political support for large projects
Where AI and Smart Grids Fit Into Zinc-Based LDES
Because this post is part of our Green Technology series, it’s worth zooming out: AI is quietly becoming the operating system for all of this new hardware.
Long-duration storage changes how you operate the grid. You’re no longer just smoothing short spikes; you’re arbitraging across hours, days, and even weather events. That’s a planning and optimization problem tailor-made for AI.
Here’s how AI and data-driven tools pair with systems like Eos’s zinc batteries:
1. Smarter dispatch and bidding
AI models can forecast:
- Renewable generation (solar, wind) hours to days ahead
- Demand patterns down to the feeder or facility level
- Market prices and congestion
Then they can optimize the dispatch of long-duration storage to:
- Reduce curtailment of renewables
- Capture higher-value peak pricing windows
- Support grid stability (frequency, voltage) at the same time
With 8–12 hour systems, these decisions are more complex than with standard 2–4 hour Li-ion. AI helps extract full value from that longer duration.
2. Asset health and lifetime optimization
Zinc systems have different degradation profiles than Li-ion. AI-driven predictive maintenance can:
- Learn how specific sites and use cases impact performance
- Recommend operating profiles that extend useful life
- Spot issues early using sensor data and anomaly detection
This directly affects project bankability. Lenders and investors care about whether a 15–20 year asset can deliver contracted performance—and credible, AI-backed O&M strategies make a difference.
3. Portfolio planning and scenario analysis
For utilities and large developers, the question isn’t “Should we use LDES?” It’s:
- How much?
- Where?
- Which technology mix (Li-ion vs zinc vs flow, etc.)?
AI planning tools can simulate thousands of grid, weather, and market scenarios and show where long-duration zinc systems outperform alternatives on:
- Net present value
- Emissions reduction
- System reliability (loss-of-load probability, etc.)
The reality: hardware like Eos’s zinc batteries and software like AI dispatch engines are converging. Neither will reach its full potential without the other.
What This Means for Developers, Utilities, and Investors
If you’re on the development, utility, or capital side of green technology, Eos’s move is a useful signal—and a practical nudge.
For project developers
You should be actively evaluating where long-duration zinc fits into your pipeline:
- Identify use cases where 4–16 hours truly pays:
- High-renewable grids with curtailment issues
- Remote or weak grid locations
- Capacity-constrained regions with evening peaks
- Model multi-service revenue: don’t just look at arbitrage; include capacity payments, ancillary services, and T&D deferral.
- Factor in safety and permitting: aqueous, non-flammable systems may clear regulatory and community hurdles faster in some locations.
For utilities and grid operators
Long-duration zinc storage is now credible enough that ignoring it in planning documents is risky.
- Add scenario runs with LDES alongside Li-ion to your resource planning.
- Consider zinc-based systems for:
- Replacing or deferring gas peakers
- Firming high-renewable portfolios
- Enhancing resilience for critical infrastructure
- Work with regulators to align tariffs and market products so that 8–12 hour assets can monetize all the services they can provide.
For investors
The honest, slightly uncomfortable truth: companies focused on non-lithium chemistries have had a mixed financial record so far. Some have struggled to get from pilot to profitable scale.
Eos is clearly aware of that history, which is why this financing matters:
- It extends the runway to reach scale manufacturing.
- It reduces financing risk by cleaning up older, more expensive debt.
- It’s underpinned by real backlog (US$644.4 million) and a large pipeline (US$22.6 billion).
You still need to underwrite the technology, execution risk, and policy stability. But this isn’t a science project stage anymore. It’s a scale-up story.
Where Green Technology Goes From Here
Eos’s US$1 billion-plus financing round is more than just a corporate milestone. It’s a sign that long-duration zinc batteries are stepping onto the main stage of the energy transition—and that US-based manufacturing is central to that story.
For the broader green technology ecosystem, the signal is clear:
- LDES is moving from “nice to have” to “core infrastructure.”
- Diverse chemistries will coexist, with zinc playing a serious role alongside lithium-ion.
- AI and smart grid software are becoming just as important as the hardware in extracting value and managing risk.
If you’re planning projects, setting strategy, or allocating capital in 2026 and beyond, now is the time to update your mental model of storage. Treat long-duration zinc-based systems not as a future technology, but as an option you need to actively evaluate.
Because the grid of the 2030s won’t be built around a single chemistry—and the companies that recognize that early will be the ones leading, not following, the energy supercycle.