ESS Inc's New CEO Bets the Company on Sodium-Ion

ESS Inc chief executive Drew Buckley said the company "wasn’t ready in 2021" as it abandons the iron flow battery technology it listed on in favour of sodium-ion battery energy storage systems, with its shares (GWH) trading at 0.40, up 3.37%, as of 20:00 GMT on 21 August 2026.

ESS Inc, the storage developer that went public in 2021 promising a long-duration iron flow battery, is abandoning that chemistry and rebuilding itself around sodium-ion battery energy storage systems. New chief executive Drew Buckley, setting out the reasoning in an interview with Energy Storage News, put the failure bluntly: the “company wasn’t ready in 2021.”

That is an unusual thing for a sitting CEO to say about the founding premise of the business he runs. It is also, for anyone who has followed the stock since its listing, not a controversial statement. ESS spent five years telling the market that iron flow — a chemistry built on iron, salt and water rather than lithium — would take over the multi-hour end of grid storage. It did not deliver on those promises at anything like the scale or timing investors were underwriting.

What the share price says about the starting point

ESS Inc (ticker: GWH) traded at 0.40 as of the last trade at 20:00 GMT on 21 August 2026, up 3.37% on the day from a previous close of 0.39, with an intraday range of 0.38 to 0.43. That is a sub-dollar quote, and it frames everything else about this pivot. A company trading at those levels has limited ability to raise equity without heavy dilution, limited ability to use its own paper for acquisitions, and limited patience left among the shareholders who bought the 2021 story.

The broader market that day was quietly positive — the S&P 500 tracker (SPY) closed the session at $765.72, up 0.41%; the Nasdaq 100 tracker (QQQ) at $713.44, up 0.35%; and the Dow tracker (DIA) at $532.22, up 0.89%. So ESS outpaced all three benchmarks on the day, but from a base where a single cent of movement is a large percentage swing. Daily moves at this price level carry very little information about whether the strategy is working.

Why sodium-ion, and why now

Sodium-ion is a different bet from iron flow, and understanding the difference matters for judging whether this pivot is a strategic reset or a retreat.

Iron flow batteries store energy in liquid electrolyte held in external tanks. The appeal is that you scale duration by adding tanks rather than cells, which theoretically makes very long discharge times — eight, ten, twelve hours — cheap. The problem, repeatedly, has been manufacturing: flow systems are plumbing as much as electrochemistry, with pumps, seals, stacks and balance-of-plant that have to work in the field for years. Turning a working prototype into a repeatable factory product has defeated more than one flow battery company.

Sodium-ion, by contrast, is architecturally close to lithium-ion. Cells, modules, racks, containers. It can be built on tooling and supply chains that already exist for lithium iron phosphate, and it swaps lithium for sodium, an abundant and geographically unconcentrated input. For a company with a damaged balance sheet, that is the crucial point: sodium-ion lets ESS buy or license a cell format and focus on integration, rather than inventing a manufacturing discipline from scratch.

The trade-off is that sodium-ion is not a differentiated niche. It is a chemistry that Chinese cell makers have already industrialised at volume, and where Western entrants are competing against an established cost curve. ESS moves from being the odd one out in a small category to being a late arrival in a crowded one.

The credibility problem Buckley has to solve first

The question Buckley is being asked is not really technical. It is whether a management team that missed its targets on one chemistry should be believed on another.

Companies that reached public markets through the 2021 SPAC window carry a particular version of this burden. Many of them listed on projections that stretched years past any commercial revenue, and the market has since re-rated the whole cohort — hard. In the storage sector specifically, capital has migrated toward businesses with signed offtake, delivered megawatt-hours and utility-grade balance sheets, not toward pre-revenue technology stories. ESS is trying to change chemistry at exactly the moment when the market’s tolerance for chemistry stories is lowest.

Companies that reached public markets through the 2021 SPAC window carry a particular version of this burden.

Buckley’s admission that the company “wasn’t ready” is a deliberate move in that context. It draws a line between the old management narrative and the new one, and it invites investors to reset their baseline rather than mark the new plan against the old promises. Whether that works depends entirely on what follows: how much cash is on hand, how long it lasts, what the order book actually contains in signed contracts rather than pipeline, and whether the first sodium-ion systems ship on a date the company states in advance and then hits.

What would count as evidence

For anyone tracking this, a handful of concrete markers will settle the question faster than any strategy deck:

A named cell supply arrangement. Sodium-ion only works as a fast pivot if ESS is not building cells itself. Who supplies them, on what terms, and at what committed volume.
A first delivered project. Not an announcement, not a memorandum of understanding — an energised system with a customer willing to be named.
Cash runway disclosed in quarters, not adjectives. At a sub-dollar share price, financing capacity is the binding constraint on every other ambition.
What happens to the iron flow installed base. Existing customers bought a technology the company is walking away from. How ESS handles warranty and service obligations will be read closely by any utility considering the new product.
Order book conversion. Whether pipeline described under the old chemistry survives the switch, or has to be rebuilt from zero.

A sector-wide pattern, not an isolated case

ESS is not alone in discovering that long-duration storage is a harder commercial problem than a technical one. Grid operators buy on delivered cost, bankability and warranty, and the incumbent — lithium iron phosphate in a container — keeps getting cheaper while alternatives argue about their theoretical advantage. Every non-lithium chemistry that has tried to break in over the past decade has run into the same wall: the benchmark is a moving target funded by enormous global manufacturing scale.

By moving to sodium-ion, ESS is at least acknowledging that reality rather than fighting it. Sodium-ion competes on the incumbent’s own terms — form factor, integration, supply chain — with a raw material argument attached. That is a more legible pitch to a utility procurement team than a flow battery ever was.

It is also, for ESS specifically, a pitch it now has to make from a much weaker position than it held in 2021. The technology is more conventional. The company is smaller, cheaper and less trusted. Buckley’s turnaround depends on whether those two facts cancel out or compound.

Key facts

Share price (GWH): 0.40, +3.37% on the day, as of 20:00 GMT, 21 Aug 2026
Intraday range: 0.38–0.43 (prev close 0.39)
Strategic change: Pivot from iron flow batteries to sodium-ion BESS
Chief executive: Drew Buckley, who said the "company wasn’t ready in 2021"

Frequently asked questions

What is ESS Inc changing about its business?

ESS Inc is moving away from iron flow batteries — the long-duration chemistry it was founded on and listed with in 2021 — and rebuilding its product line around sodium-ion battery energy storage systems. New chief executive Drew Buckley described the earlier period by saying the "company wasn’t ready in 2021," acknowledging that ESS did not deliver on its original iron flow commitments.

How is the ESS Inc share price performing?

ESS Inc shares, ticker GWH, last traded at 0.40, up 3.37% from a previous close of 0.39, as of 20:00 GMT on 21 August 2026. The intraday range was 0.38 to 0.43. That day the stock outperformed the S&P 500, Nasdaq 100 and Dow trackers, though at a sub-dollar price small absolute moves produce large percentage swings.

What is the difference between iron flow and sodium-ion batteries?

Iron flow batteries store energy in liquid electrolyte held in external tanks, so duration is scaled by adding tanks rather than cells. They involve pumps, seals and extensive plumbing, which has made manufacturing difficult. Sodium-ion is structurally similar to lithium-ion — cells, modules, racks and containers — and can reuse existing lithium-ion tooling and supply chains, substituting abundant sodium for lithium.

Why does the 2021 listing matter to the story?

ESS went public in 2021 on the strength of iron flow battery projections it subsequently failed to meet. That history shapes how the sodium-ion pivot is received: investors are being asked to trust the same corporate vehicle on a second chemistry after the first one disappointed. The current sub-dollar share price reflects how much of the original story the market has written off.

Is sodium-ion a differentiated technology for ESS?

Less so than iron flow was. Sodium-ion has already been industrialised at volume by large Chinese cell manufacturers, so ESS would be entering an established and competitive category rather than pioneering a niche. The advantage is that sodium-ion can be integrated using existing lithium-ion-style supply chains, which lowers the capital and execution burden for a company with constrained finances.

What should investors watch next from ESS Inc?

Key markers include a named sodium-ion cell supply arrangement, a first delivered and energised project with an identified customer, disclosed cash runway in quarters, how ESS services warranty obligations on its existing iron flow installations, and whether any of its previously reported pipeline converts into signed sodium-ion contracts rather than having to be rebuilt from scratch.

Sources

‘Company wasn’t ready in 2021’: ESS Inc CEO on pivoting away from iron flow batteries to sodium-ion — Energy Storage News

Photo: Griffin Wooldridge · Pexels Licence — source