What are the fundraising trends in the LDES market?
In our LDES market deck, you will find everything you need to understand the market
SUMMARY
We analyzed every publicly disclosed equity round raised by pure-play long-duration energy storage companies between January 2024 and May 2026. We only kept disclosed equity rounds of $300K or more, excluded grants, debt, project finance, undisclosed rounds, non-pure-play companies, and storage businesses that do not primarily operate as electricity-storage systems designed for 10-plus-hour discharge.
The resulting LDES market dataset contains 38 qualifying deals across 37 unique companies: 16 deals in full-year 2024, 18 deals in full-year 2025, and 4 deals in year-to-date 2026 through May 2026. Across those disclosed rounds, the market raised about $1.25B in 2024, about $998M in 2025, and about $324M in year-to-date 2026.
Less capital is going into the LDES market on the cleanest full-year comparison. Funding fell from about $1.25B in 2024 to about $998M in 2025, even as deal count rose from 16 to 18, which means the market became broader by activity but smaller by dollars.
The freshest 2026 signal is narrower than the headline number suggests. Year-to-date 2026 funding is about $324M across 4 deals, down slightly from about $352M over the comparable early-2025 period, but EnerVenue alone accounts for almost 93% of current-year capital.
The LDES market is structurally top-heavy. The top 3 deals captured about 69% of capital in 2024, about 67% in 2025, and almost all year-to-date 2026 capital, so total funding is mainly a measure of whether a few scale-up companies raised large rounds.
Round sizes are getting smaller for the typical LDES company. The median round fell from about $32M in 2024 to $20M in 2025 and then to $11.5M in year-to-date 2026, while the average remains distorted by very large rounds.
Capital is moving toward later-stage and follow-on companies. In year-to-date 2026, late-stage or Series B-plus companies captured about 97% of disclosed capital, while early-stage companies captured less than 3%.
Electrochemical LDES remains the most active category by deal count, but the capital story rotated sharply. Electrochemical LDES captured about 79% of 2024 capital, only about 10% of 2025 capital, and then 100% of year-to-date 2026 capital because every current-year qualifying deal so far is electrochemical.
Mechanical storage, grid LDES systems, and behind-meter LDES gained the strongest full-year momentum in 2025. Hydrostor, Highview Power, Energy Vault, RayGen, and Exowatt show that investors increasingly fund companies with project, infrastructure, manufacturing, or urgent demand-pull narratives, not just novel storage chemistry.
North America remains the deepest capital market for LDES. Europe became more visible in 2025, and Asia-Pacific continues to produce credible companies, but the largest checks still cluster disproportionately in North America, especially when a single large EnerVenue round defines the current-year numbers.
This chart, featured in our LDES market deck, illustrates how revenue is divided among customer segments in the LDES market
Is more or less capital going into the LDES market?
Less capital is going into the LDES market, but the answer depends on whether the reader cares most about the freshest signal or the cleaner full-year signal. So far in 2026, disclosed LDES equity funding is about $324M, down slightly from about $352M over the comparable January through May 2025 period.
That recent decline is not dramatic in dollar terms, but it is fragile because 2026 activity is based on only 4 qualifying deals. One EnerVenue round accounts for nearly 93% of all 2026 capital so far, which means the current-year total is mostly one company signal rather than a broad market signal.
The fuller comparison is more reliable and also points downward. Full-year 2025 disclosed capital was about $998M, down from about $1.25B in 2024. That is roughly a 20% decline in total funding, even though deal count increased from 16 deals in 2024 to 18 deals in 2025.
The practical takeaway is that the LDES market is not being abandoned, but the capital pool is becoming more selective. In 2024, the market was powered by large electrochemical rounds such as Form Energy and EnerVenue. In 2025, the market still produced major checks, including Energy Vault, Hydrostor, Highview Power, RayGen, and Exowatt, but the total was lower and capital shifted toward infrastructure-style platforms.
The strongest evidence is the combination of falling total capital, rising deal count in 2025, falling average round size, and extreme 2026 concentration. Average round size fell from about $78M in 2024 to about $59M in 2025, while median round size fell from about $32M to $20M. So the LDES market is receiving less capital overall, and the typical company is also raising less.
Is LDES funding driven by more deals or larger rounds?
LDES funding is increasingly driven by more deals rather than larger rounds, at least in the cleaner full-year comparison between 2025 and 2024. Full-year deal count rose from 16 in 2024 to 18 in 2025, but total capital fell from about $1.25B to about $998M.
That means the LDES market became broader in deal count but smaller in total dollars. This is an important distinction because more financings can make the market feel active while the actual amount of capital available to each company declines.
The round-size indicators make the answer clearer. Average round size fell from about $78M in 2024 to about $59M in 2025. Median round size fell from about $32M to $20M. The median matters because the LDES market is highly skewed by large rounds; a lower median means the typical financed company received a smaller check.
So far in 2026, the freshest signal points in the opposite direction, but it is too thin to treat as a durable market-wide pattern. The LDES market has only 4 qualifying deals through May 2026, compared with 3 over the same period in 2025. Capital is slightly lower, but the average round size is distorted by EnerVenue’s $300M financing.
The better conclusion is that full-year 2025 funding activity was driven by more deals, not larger rounds. The 2026 year-to-date period is too concentrated to call a reversal.
For deeper benchmarks on LDES deal sizes, medians, and round distributions, see our LDES market deck.
Is LDES capital moving toward later-stage or earlier-stage companies?
LDES capital is moving decisively toward later-stage and follow-on companies, not earlier-stage companies. The clearest current signal is year-to-date 2026: late-stage or Series B-plus companies captured about $315M, or 97% of disclosed capital, while early-stage companies captured only about $8.8M.
The full-year comparisons confirm the same structural pattern. In 2024, Series B-plus companies captured about $1.1B, or 88% of capital. In 2025, late-stage, growth, and Series D capital captured about $634M, or 64%, while seed and Series A captured about $136M, with another $228M in unknown-stage capital.
The deal-count view adds nuance. Early-stage companies are still appearing. Seed and Series A represented half of 2024 deals and about half of 2025 deals if seed and Series A are combined. So the LDES market is not closed to new entrants.
But early-stage rounds are small relative to scale-up financings. In 2025, seed and pre-seed rounds averaged only about $4M, while growth equity averaged about $138M. In 2026 so far, seed rounds average about $4.4M, while EnerVenue alone raised $300M at Series B.
The honest interpretation is that capital is not moving toward invention; it is moving toward commercialization. Investors are still sampling early technical approaches, especially electrochemical LDES, but the serious dollars are going to companies that can credibly finance manufacturing, deployment, project execution, or platform scale.
This chart, included in our LDES market deck, compares the main business model options for long-duration energy storage developers
Is the LDES market maturing or still experimental?
The LDES market is maturing in capital allocation, but it remains experimental in technology architecture. The strongest evidence of maturity is that most capital is flowing to follow-on companies, later-stage rounds, strategic investors, project platforms, and manufacturing scale-up.
The strongest evidence of experimentation is that capital still touches many technical approaches. Across the dataset, funded companies include iron-air, nickel-hydrogen, flow batteries, zinc systems, thermal-to-power, compressed air, liquid air, offshore pumped hydro, gravity, and behind-meter thermal systems.
The 2025 full-year comparison is the best lens for market maturity because it covers a complete year and avoids overreading the thin 2026 year-to-date period. In 2025, first financings were 22% of deals but only 1% of disclosed capital. In 2024, first financings were 19% of deals but only 3% of capital.
That means new-company formation exists, but capital is mostly not behaving like early discovery capital. It is behaving like commercialization capital.
Still, the LDES market is not fully mature. A mature market would show repeatable project finance, standardized buyer behavior, more repeat investors, and less dependence on a few large rounds. In 2025, the top 3 deals captured about 67% of capital. In 2026 so far, the top deal captured nearly 93%.
Are new startups still entering the LDES market?
Yes, new startups are still entering the LDES market, but new entrants are not receiving much capital. The best full-year comparison is 2025 versus 2024: first financings increased from 3 deals in 2024 to 4 deals in 2025, and the share of deals that were first financings rose from about 19% to about 22%.
That means new-company formation did not disappear. The LDES market is still producing new teams, new architectures, and new early-stage companies.
The capital share tells a very different story. First financings captured only about 3% of 2024 capital and only about 1% of 2025 capital. Investors are writing small exploratory checks into new companies, not funding them at anything close to the scale of follow-on companies.
So far in 2026, the signal is even more extreme. Meine Electric is the only first financing among 4 qualifying deals, so first financings represent 25% of deal count. But its $0.75M round represents only about 0.2% of year-to-date 2026 capital.
The better interpretation is that the LDES market remains open to new technical teams, especially at seed stage, but the financing environment is not treating new startups as the center of gravity. New startups are entering the LDES market, but the money is going to companies with prior validation.
For the broader category view across LDES startups, first financings, and company formation, see our full LDES market report.
Are more investors entering the LDES market?
Investor breadth in the LDES market looks broadly stable, not explosively expanding. Full-year 2024 had about 75 unique disclosed investors and 35 unique tier-1 or strategic institutional investors. Full-year 2025 had at least 71 named disclosed investors and 19 tier-1 investors by the stricter classification used in the dataset.
Because the tier-1 definitions are not perfectly identical across the two years, the exact tier-1 decline should not be overinterpreted. But the broad signal is clear: the investor base did not expand dramatically in 2025.
The deal count increased from 16 to 18 between 2024 and 2025, but the number of disclosed investors did not rise with it. That means investor participation per deal likely became thinner or more selective.
The freshest 2026 signal is weaker. So far in 2026, only 12 disclosed investors are visible across 4 deals, excluding unnamed institutional investors. Only 2 are classified as tier-1 under the strict 2026 definition.
The most defensible conclusion is that investor quality remains meaningful, but investor breadth is not obviously growing. The LDES market attracts serious investors when a company has a credible scale-up story, but it is not yet a market where many investors repeatedly deploy across the category.
This chart, included in our LDES market deck, illustrates yearly funding for LDES startups
Are top investors getting more or less active in LDES?
Top investors appear to be getting less consistently active across the LDES market, even though several high-quality investors are still participating in major deals. In 2024, Breakthrough Energy Ventures appeared in 3 qualifying deals, while SLB, Temasek, and Prelude Ventures each appeared in 2.
That created a visible set of repeat category backers. It made the 2024 LDES market look more like a recognizable climate-infrastructure thesis, with several marquee investors placing more than one bet.
In 2025, repeat activity became thinner and more fragmented. The disclosed investors appearing in more than one deal were MVP Ventures, 8090 Industries, StepStone Group, and Antares Ventures, each with 2 deals. Those are meaningful investors, but the pattern looks more company-specific than category-wide.
So far in 2026, no disclosed investor appears in more than one qualifying deal. That current-year signal should be treated cautiously because only 4 deals have occurred through May 2026, but it still matters. A healthy repeat-investor market would normally show at least some familiar names across multiple financings.
The better interpretation is that top investors have not disappeared; they have become more selective. The LDES market is still thesis-driven and case-by-case, not a repeatable deployment category for most top investors.
Which LDES subcategories are gaining momentum?
The subcategories gaining momentum in the LDES market are mechanical storage systems, grid LDES systems, behind-meter LDES, and, in the freshest 2026 period, electrochemical LDES. The most reliable full-year signal is 2025 versus 2024.
Mechanical storage rose from only about $6M in 2024 to about $379M in 2025. Grid LDES systems rose from zero disclosed capital in 2024 to $300M in 2025. Behind-meter LDES rose from $20M in 2024 to $120M in 2025.
Mechanical storage momentum is especially important because it was not just more deals; it was larger, infrastructure-style funding. Hydrostor raised $200M, Highview Power raised about $171M, and Sizable Energy added $8M. That pattern suggests investors became more willing to fund LDES platforms that look like infrastructure-development businesses rather than only venture-backed technology companies.
Grid LDES systems gained momentum because Energy Vault’s $300M preferred equity investment created a category-scale funding event. One deal is not enough to prove broad category depth, but it is enough to prove that asset-platform models can attract very large checks.
The 2026 year-to-date signal points back toward electrochemical LDES, because all 4 qualifying deals and 100% of capital so far are electrochemical. But that signal is narrow and heavily distorted by EnerVenue’s $300M round.
We cover this subcategory shift in more detail in our market report covering LDES subcategory momentum.
Which LDES subcategories are losing momentum?
Electrochemical LDES lost major full-year capital momentum from 2024 to 2025, even though it remained the most active category by deal count. In 2024, electrochemical LDES captured about $989M, or 79% of total capital. In 2025, it captured only about $97M, or 10% of capital.
Deal count stayed high at 9 electrochemical deals in 2025, but the dollars shifted away from electrochemical companies toward mechanical systems, grid platforms, and behind-meter systems. That means category activity remained high while category capital conviction weakened.
Thermal Storage Power also lost full-year capital momentum. Thermal Storage Power fell from about $232M in 2024 to about $102M in 2025. The decline is not a sign that thermal-to-power is irrelevant, because RayGen and Fourth Power both raised in 2025, but the category moved down from a stronger 2024 position.
The freshest 2026 period complicates the interpretation. Through May 2026, electrochemical LDES accounts for all qualifying deals and all capital, while thermal, mechanical, grid, chemical, and behind-meter categories have no qualifying equity deals. But the period has only 4 deals, so the absence of non-electrochemical financings should be treated as preliminary rather than a confirmed collapse.
The better answer is that, on the most reliable full-year basis, electrochemical LDES and Thermal Storage Power lost capital share in 2025, while mechanical, grid-platform, and behind-meter models gained. On the freshest 2026 basis, non-electrochemical categories have not yet shown up, but the period is too thin to call a durable loss of momentum.
This chart, included in our LDES market deck, looks at Form Energy’s strategy in long-duration energy storage
Which regions are gaining momentum in LDES funding?
Europe gained the clearest full-year momentum in the LDES market from 2024 to 2025. European capital rose from about $88M in 2024 to about $187M in 2025, and Europe’s capital share increased from about 7% to about 19%.
European deal count also rose from 3 deals to 5 deals. That combination of higher dollars and higher deal count makes Europe’s momentum more credible than a single large round would.
Asia-Pacific remained active, but its momentum was more selective. Asia-Pacific capital was broadly similar between 2024 and 2025, while deal count moved from 5 deals to 4 deals. The region still produced meaningful activity through companies such as RayGen, VFlowTech, Sthyr, and H2, but the full-year signal is not as strong as Europe’s.
North America remained the dominant region, but it did not gain share on the full-year comparison. North American capital fell from about $1.04B in 2024 to about $692M in 2025, and its capital share declined from about 83% to about 69%.
So far in 2026, North America has regained overwhelming capital dominance because EnerVenue and ESS together account for $315M, or 97% of year-to-date capital. That 2026 signal is fresh but extremely concentrated.
Which regions are losing momentum in LDES funding?
North America lost full-year capital share from 2024 to 2025, even though it remained the largest LDES market by far. North America captured about 83% of capital in 2024 and about 69% in 2025.
In dollar terms, North American funding fell from about $1.04B to about $692M. That is a meaningful decline, not just a rounding issue.
Asia-Pacific lost some deal-count momentum from 2024 to 2025. Asia-Pacific had 5 deals in 2024 and 4 deals in 2025. Capital was broadly similar, so the region did not collapse, but it did not show the same increase in breadth that Europe showed.
Europe did not lose momentum on a full-year basis; it gained. The caveat is that Europe’s median deal size remained low, about $7.5M in 2025. Europe produced more visible activity, but not many very large rounds.
The freshest 2026 year-to-date signal makes Europe and Asia-Pacific look weak because North America captured 97% of capital through May 2026. But that signal is mostly EnerVenue. The better interpretation is that North America lost share in 2025 but remains dominant, Asia-Pacific softened in breadth, and Europe gained full-year momentum but has not yet shown large 2026 capital formation.
Is LDES becoming more global or regionally concentrated?
The LDES market became more global in 2025 compared with 2024, but the freshest 2026 signal looks regionally concentrated again. The full-year comparison is the more reliable indicator of structural geographic spread.
In 2024, North America captured about 83% of capital, Asia-Pacific about 10%, and Europe about 7%. In 2025, North America’s share fell to about 69%, Europe rose to about 19%, and Asia-Pacific held about 12%. That is a more globally distributed capital pattern.
The deal-count split also supports a broader 2025 market. In 2025, North America had 50% of deals, Europe had about 28%, and Asia-Pacific had about 22%. That is more balanced than the capital split, which shows that non-North American regions are producing companies but not always rounds of North American scale.
The 2026 year-to-date comparison pulls in the opposite direction. North America has 50% of deals but 97% of capital through May 2026. Europe and Asia-Pacific each have one deal, but together they represent less than 3% of capital.
The best reading is that the LDES market is becoming more global in company activity, but still regionally concentrated in capital depth. Europe and Asia-Pacific are visible sources of LDES startups and mid-sized rounds. North America remains the place where the largest checks are most likely to appear.
For ongoing regional tracking across North America, Europe, Asia-Pacific, and other regions, see our full market view on LDES regional funding.
This chart, included in our LDES market deck, shows how grid resilience needs have driven growth in the long-duration energy storage market over time
Is LDES capital moving toward proven winners or new opportunities?
LDES capital is moving toward proven winners, not new opportunities. The strongest evidence is the follow-on capital share. In 2024, first financings represented about 19% of deals but only 3% of capital. In 2025, first financings represented about 22% of deals but only 1% of capital.
So new opportunities exist, but capital is overwhelmingly flowing to companies that have already raised before. The LDES market is still open to discovery, but it is not allocating most of its dollars to discovery-stage companies.
The 2026 year-to-date period is even more decisive. First financings represent 25% of deals because Meine Electric raised a first financing, but first financings represent only about 0.2% of capital. Meanwhile, EnerVenue, a follow-on company, accounts for nearly 93% of all year-to-date capital.
Stage mix confirms the same conclusion. Late-stage and Series B-plus capital represented 88% of 2024 capital, 64% of 2025 capital excluding unknown-stage ambiguity, and 97% of 2026 year-to-date capital.
The practical interpretation is that investors are willing to fund novelty, but only cheaply. The expensive capital is reserved for companies with more proof: manufacturing plans, deployment pathways, strategic investors, public-market access, infrastructure capital, or commercial demand.
Our LDES market report tracks these follow-on companies over time, with more detail on which companies keep attracting scale capital and which new entrants still need to prove they can raise again.
Is the LDES market becoming winner-takes-most?
Yes, the LDES market is becoming winner-takes-most in capital allocation, though not yet winner-takes-all in technology architecture. The strongest current evidence is year-to-date 2026: the largest deal, EnerVenue’s $300M financing, represents nearly 93% of all disclosed capital through May 2026.
The full-year data shows that this concentration is not new. In 2024, the largest deal captured about 32% of total capital, the top 3 captured about 69%, and the top 5 captured about 81%. In 2025, the largest deal captured about 30%, the top 3 about 67%, and the top 5 about 83%.
The exact leading companies changed, but the concentration structure persisted. That means the LDES market is winner-takes-most financially even while technology remains plural.
Capital has funded multiple architectures across years, but within each year the majority of dollars go to only a few companies. Category diversity should not be mistaken for equal investor conviction.
The most useful reading rule is simple: deal count measures experimentation, while top-deal share measures conviction. By that rule, the LDES market is still experimental in technology but winner-takes-most in financing.
Is the next wave of LDES winners becoming visible?
Yes, the next wave of LDES winners is becoming visible, but the evidence is uneven and should be weighted carefully. The most visible winners are not necessarily the newest companies; they are the companies that combine large capital raises with credible deployment, manufacturing, strategic backing, or demand-pull narratives.
EnerVenue, Hydrostor, Energy Vault, Highview Power, RayGen, Exowatt, Form Energy, Antora, and Invinity are the clearest names across the 2024 through 2026 evidence. They are visible because they raised scale capital, repeated in the dataset, or attracted investors that imply commercialization credibility.
The strongest signal is repeat or scale capital. EnerVenue raised about $308M in 2024 and another $300M in 2026. RayGen raised about $33M in 2024 and about $82M in 2025. Exowatt raised $20M in 2024 and then two rounds totaling $120M in 2025.
The next-wave signal is also visible in subcategory rotation. In 2024, large electrochemical platforms dominated. In 2025, infrastructure-like mechanical and grid-platform models became much more prominent. In 2026 so far, selected electrochemical platforms have regained the capital lead.
The caution is that visibility is not the same as confirmed dominance. The LDES market still lacks broad evidence of repeated bankable deployments across many companies. Large equity rounds identify likely finalists, not guaranteed winners.
For more context on the emerging cohort of LDES winners and the signals that separate durable companies from one-off experiments, see our deeper analysis of the LDES market.
As this chart shows, and as featured in our LDES market deck, search interest in long-duration energy storage has been rising steadily
Is the LDES funding landscape fragmenting or consolidating?
The LDES funding landscape is consolidating in capital but fragmenting in technology and company formation. The capital side is clearly consolidating: the top 3 deals captured about 69% of 2024 capital, about 67% of 2025 capital, and almost all 2026 year-to-date capital.
The bottom half of deals captured only about 8% of 2024 capital, 5% of 2025 capital, and 3% of 2026 year-to-date capital. That is not a broad capital market. It is a market where most companies remain lightly funded while a few perceived winners absorb the serious dollars.
The technology side remains fragmented. Across 2024 and 2025, funding touched iron-air, nickel-hydrogen, vanadium flow, organic flow, zinc-air, zinc-bromine, acid-base flow, thermal carbon, thermochemical, sand, compressed air, liquid air, pumped-hydro-style ocean storage, gravity storage, and behind-meter dispatchable thermal systems.
The investor side is also fragmented. Repeat-investor activity exists but is limited. In 2024, a few names such as Breakthrough Energy Ventures, SLB, Temasek, and Prelude Ventures appeared repeatedly. In 2025, repeat activity shifted to a different, smaller set of investors. In 2026 so far, no disclosed investor appears in more than one qualifying deal.
So the answer is both. Capital is consolidating around perceived winners, while the broader LDES landscape remains fragmented across technologies, business models, regions, and investor syndicates.
Where is investor attention shifting in LDES?
Investor attention in the LDES market is shifting away from broad technology discovery and toward bankable scale-up, infrastructure platforms, and urgent demand-pull use cases. The clearest full-year evidence is the shift from 2024 to 2025.
In 2024, electrochemical LDES captured about 79% of capital. In 2025, electrochemical LDES still had 50% of deals but only about 10% of capital, while mechanical storage and grid LDES systems together captured about 68% of capital.
Investor attention is also shifting toward behind-meter power constraints, especially data centers and industrial loads. Behind-meter LDES grew from $20M in 2024 to $120M in 2025, largely because Exowatt raised multiple rounds. That matters because behind-meter LDES can be funded by a different urgency than grid-scale procurement: power availability, AI infrastructure, and time-to-power constraints can pull capital forward.
The 2026 year-to-date signal points back toward electrochemical LDES, but in a narrower way. All 4 qualifying 2026 deals are electrochemical, and EnerVenue dominates capital. This should not be read as a broad return to every electrochemical architecture. It is better read as investor attention shifting toward electrochemical companies that can credibly industrialize.
The strongest overall interpretation is that investor attention is shifting from “can this technology store energy for 10-plus hours?” to “can this company finance, manufacture, deploy, and monetize 10-plus-hour electricity storage?” Duration claims are now table stakes. The funding premium goes to companies with commercialization evidence.
For real-time tracking of how investor attention is moving across electrochemical LDES, mechanical systems, grid platforms, thermal-to-power, and behind-meter storage, see our full LDES market report.
All the funding deals in the long-duration energy storage market from 2024 to Mar 2026
The table below lists every disclosed funding deal in the supplied long-duration energy storage dataset from 2024 through March 2026, covering electrochemical, thermal, mechanical, grid-scale, and behind-the-meter storage companies.
Each row shows the company, the fundraising date, what the company does, its category, the funding stage, the round size, the region, whether it was a first financing or a follow-on, the tier-1 investor if any, and the announcement source. For the broader investability view, see our market report.
| Company | Date | What they do | Category | Stage | Deal size | Region | First/Follow-on | Tier 1 investor(s) | Source |
|---|---|---|---|---|---|---|---|---|---|
| EnerVenue | Mar 2026 | Builds aqueous metal / metal-hydrogen batteries for large-scale and long-duration energy storage. | Electrochemical LDES | Series B | $300M | North America | Follow-on | Hong Kong Investment Corporation Limited | Full Vision Capital |
| Sinergy Flow | Feb 2026 | Develops low-cost sulfur-based redox flow batteries for long-duration stationary storage, supporting grid and renewable integration. | Electrochemical LDES | Seed | $8M | Europe | Follow-on | CDP Venture Capital SGR | CDP Venture Capital |
| ESS Tech, Inc. | Jan 2026 | Manufactures iron-flow long-duration energy storage systems for commercial and utility-scale applications. | Electrochemical LDES | Growth Equity | $15M | North America | Follow-on | None disclosed | Business Wire |
| Meine Electric | Jan 2026 | Develops iron-air batteries for long-duration energy storage, targeting 16–24 hour storage and grid / C&I renewable firming. | Electrochemical LDES | Seed | $0.75M | Asia-Pacific | First financing | None clearly identifiable as tier-1 under strict global institutional standard | EV Reporter |
| Kodiaq Technologies | Dec 2025 | Develops organic, metal-free electrolytes for flow batteries and long-duration storage. | Electrochemical LDES | Seed | $1.1M | Europe | First financing | None identified | UKTN |
| Exowatt | Nov 2025 | Behind-meter long-duration thermal battery and dispatchable solar power for data centers and industrial loads. | Behind Meter LDES | Growth Equity | $50M | North America | Follow-on | StepStone; MVP Ventures; 8090 Industries | ESG Today |
| Highview Power | Nov 2025 | Develops liquid-air energy storage for 12+ hour grid-scale electricity storage. | Mechanical Storage Systems | Growth Equity | $171.1M | Europe | Follow-on | Goldman Sachs; Centrica; KIRKBI; Scottish National Investment Bank | Business Wire |
| Quino Energy | Nov 2025 | Develops water-based organic flow batteries for long-duration energy storage. | Electrochemical LDES | Series A | $10M | North America | Follow-on | None identified | pv magazine USA |
| Flux XII | Nov 2025 | Develops aqueous organic flow batteries and materials for grid-scale long-duration energy storage. | Electrochemical LDES | Seed | $3.95M | North America | First financing | Grantham Foundation | Business Wire |
| Sizable Energy | Oct 2025 | Develops offshore pumped hydro / gravity storage using brine and ocean depth for grid-scale long-duration energy storage. | Mechanical Storage Systems | Seed | $8M | Europe | Follow-on | Playground Global | Business Wire |
| Energy Vault | Oct 2025 | Grid-scale storage platform and IPP asset platform for storage projects, including gravity, hybrid storage, and multi-hour grid shifting. | Grid LDES Systems | Growth Equity | $300M | North America | Follow-on | OIC | Energy Vault |
| XL Batteries | Sep 2025 | Develops organic flow battery systems for industrial and data-center long-duration storage. | Electrochemical LDES | Unknown | $7.5M | North America | Follow-on | None identified | Energy-Storage.news |
| Unbound Potential | Sep 2025 | Develops membrane-free redox flow batteries for stationary storage. | Electrochemical LDES | Seed | $6.9M | Europe | First financing | Founderful; Kvanted; Zürcher Kantonalbank | Startupticker |
| Fourth Power | Sep 2025 | Utility-scale thermal energy storage that stores electricity as heat in carbon blocks and converts it back to electricity via thermophotovoltaics. | Thermal Storage Power | Series A | $20M | North America | Follow-on | Breakthrough Energy Ventures; DCVC; Munich Re Ventures | Business Wire |
| Offgrid Energy Labs | Sep 2025 | Develops zinc-bromine battery systems for stationary storage, with reported discharge range reaching long-duration thresholds. | Electrochemical LDES | Series A | $15M | Asia-Pacific | Follow-on | None identified | TechCrunch |
| Energy Dome | Jul 2025 | CO2 Battery long-duration storage for renewable electricity shifting, designed to store power up to 24 hours. | Mechanical Storage Systems | Unknown | Undisclosed | Europe | Follow-on | Energy Dome | |
| ESS Inc. / ESS Tech | Jul 2025 | Develops iron flow batteries for commercial and utility-scale long-duration storage. | Electrochemical LDES | Growth Equity | $31M | North America | Follow-on | None identified | ESS Inc. |
| Sthyr Energy | Jun 2025 | Develops mechanically rechargeable zinc-air batteries for seasonal and long-duration storage. | Electrochemical LDES | Seed | $1M | Asia-Pacific | First financing | None identified | Chemical Industry Digest |
| VFlowTech | May 2025 | Develops vanadium redox flow battery systems for long-duration energy storage, with manufacturing and energy-management software. | Electrochemical LDES | Unknown | $20.5M | Asia-Pacific | Follow-on | Granite Asia; EDBI | VFlowTech |
| Exowatt | Apr 2025 | Modular behind-meter dispatchable solar thermal system that captures solar and grid energy as heat and converts it to electricity on demand. | Behind Meter LDES | Series A | $70M | North America | Follow-on | Felicis; Andreessen Horowitz; Thrive Capital; StepStone Group; Starwood Capital | ESS News |
| RayGen | Apr 2025 | Solar-plus-thermal hydro storage system using concentrated PV/thermal generation and water reservoirs for dispatchable long-duration power. | Thermal Storage Power | Series D+ | $82M | Asia-Pacific | Follow-on | SLB; Equinor Ventures; AGL Energy; Quanta Services | RayGen |
| Hydrostor | Feb 2025 | Advanced compressed-air energy storage developer and operator for grid-scale long-duration storage projects. | Mechanical Storage Systems | Unknown | $200M | North America | Follow-on | Goldman Sachs Alternatives; CPP Investments; Canada Growth Fund | Business Wire |
| H2, Inc. | Dec 2024 | Develops vanadium flow battery systems for long-duration storage and is expanding flow-battery manufacturing capacity. | Electrochemical LDES | Unknown | $16M | Asia-Pacific | Follow-on | STIC Investments | PR Newswire |
| Skip Technology | Nov 2024 | Develops hydrogen-bromine long-duration battery technology for large-scale storage use cases. | Electrochemical LDES | Seed | $5M | North America | Follow-on | None clearly identifiable as global tier-1 financial investors; Puyallup Tribal Enterprises is a strategic/community investor | GeekWire |
| RedoxBlox | Oct 2024 | Develops thermochemical energy storage for industrial decarbonization and grid-scale long-duration energy storage. | Thermal Storage Power | Series A | $40.7M | North America | Follow-on | Prelude Ventures; Breakthrough Energy Ventures; Khosla Ventures | Yahoo Finance |
| Green Gravity | Oct 2024 | Develops gravity-based energy storage using weighted systems in mine shafts and other vertical infrastructure. | Mechanical Storage Systems | Series A | $6.02M | Asia-Pacific | Follow-on | HMC Capital; BlueScopeX; SCAPH/Sumitomo-linked strategic capital | Energy-Storage.news |
| Form Energy | Oct 2024 | Develops iron-air batteries for multi-day electricity storage. | Electrochemical LDES | Series D+ | $405M | North America | Follow-on | T. Rowe Price; GE Vernova; TPG Rise Climate; Breakthrough Energy Ventures; Coatue; Energy Impact Partners; Temasek; GIC; Prelude Ventures | Form Energy |
| VRB Energy | Sep 2024 | Develops and manufactures vanadium redox flow batteries for long-duration stationary storage. | Electrochemical LDES | Growth Equity | $55M | Asia-Pacific | Follow-on | Red Sun; strategic investor | Ivanhoe Electric |
| Allegro Energy | Sep 2024 | Develops water-based redox flow batteries and other electrochemical storage systems for long-duration use. | Electrochemical LDES | Series A | $11.6M | Asia-Pacific | Follow-on | The Grantham Foundation; Origin Energy | pv magazine |
| e-Zinc | Jun 2024 | Develops zinc-air long-duration energy storage systems designed for 24-hour to multi-day discharge. | Electrochemical LDES | Series A | $31M | North America | Follow-on | Evok Innovations; Mitsubishi Heavy Industries; Export Development Canada; Toyota Ventures; Eni Next; BDC | e-Zinc |
| EnerVenue | Jun 2024 | Develops nickel-hydrogen batteries for stationary energy storage and long-duration applications. | Electrochemical LDES | Series B | $308.15M | North America | Follow-on | SLB; Stanford University | TechCrunch |
| Invinity Energy Systems | May 2024 | Manufactures vanadium flow batteries for long-duration stationary energy storage. | Electrochemical LDES | Growth Equity | $72.9M | Europe | Follow-on | UK Infrastructure Bank/National Wealth Fund; Korea Investment Partners | London Stock Exchange |
| RayGen | Apr 2024 | Develops solar-plus-thermal-hydro long-duration storage systems capable of dispatching electricity for long periods. | Thermal Storage Power | Series D+ | $33.1M | Asia-Pacific | Follow-on | SLB; Breakthrough Victoria | RayGen |
| AQUABATTERY | Apr 2024 | Develops saltwater-based long-duration energy storage using acid-base flow battery chemistry. | Electrochemical LDES | Seed | $6.5M | Europe | First financing | EIT InnoEnergy; Invest-NL | AQUABATTERY |
| Exowatt | Apr 2024 | Builds modular solar-thermal energy systems for data centers, combining heat collection, thermal storage, and dispatchable power generation. | Behind Meter LDES | Seed | $20M | North America | First financing | Andreessen Horowitz; Sam Altman | Exowatt |
| Alsym Energy | Apr 2024 | Develops non-lithium, non-flammable rechargeable batteries for stationary storage, with disclosed duration capability spanning long-duration use cases. | Electrochemical LDES | Series C | $78M | North America | Follow-on | Tata Limited; General Catalyst | Electrek |
| Polar Night Energy | Apr 2024 | Develops sand-based high-temperature thermal storage systems, including a roadmap toward power-to-heat-to-power readiness. | Thermal Storage Power | Seed | $8.2M | Europe | First financing | None clearly identifiable as global tier-1 financial investors; Jonathan Oppenheimer is a notable strategic/HNW investor | pv magazine |
| Antora Energy | Feb 2024 | Builds thermal batteries that store electricity as high-temperature heat in carbon blocks and convert stored heat back to electricity using thermophotovoltaics. | Thermal Storage Power | Series B | $150M | North America | Follow-on | Decarbonization Partners; BlackRock; Temasek; Breakthrough Energy Ventures; BHP Ventures; NextEra Energy Resources | Antora Energy |
INSIGHTS
The insights below come from reviewing every disclosed equity round in the LDES market between January 2024 and May 2026, including full-year 2024, full-year 2025, and year-to-date 2026 through May 2026.
- The LDES market is best understood as a two-layer market: a small, capital-heavy scale-up layer and a broader, undercapitalized experimentation layer. The scale-up layer determines total funding, while the experimentation layer determines technology diversity.
- Deal count is a poor proxy for investor conviction in the LDES market. Electrochemical LDES had half of 2025 deals but less than 10% of capital, which means category activity can remain high even while capital conviction shifts elsewhere.
- Total capital is also a poor proxy for market health unless concentration is shown. In 2026 so far, the LDES market looks strong only if EnerVenue is included without context; excluding the largest deal leaves only about $24M of capital.
- The median round is more useful than the average round in this market. The 2026 average round is about $81M, but the median is only $11.5M, which means the average mostly reflects one large financing rather than the normal funding environment.
- The most reliable maturity signal is not stage label, because stage labels vary widely across public companies, private startups, project platforms, and infrastructure vehicles. Use of proceeds is more informative: manufacturing scale-up, project execution, and asset ownership indicate more maturity than seed-stage chemistry validation.
- First financings are useful as a startup-formation signal but weak as a market-strength signal. First financings represented about one-fifth to one-quarter of deals across 2024, 2025, and year-to-date 2026, but never represented more than a few percent of capital.
- The LDES market is not short of technical imagination. The persistent appearance of many chemistries and storage architectures indicates that the bottleneck is not invention; the bottleneck is proof that a system can be financed, deployed, operated, and purchased at scale.
- Strategic investors matter because they reduce interpretation risk. A large round with a utility, infrastructure investor, industrial corporate, public bank, or sovereign-backed investor should be weighted more heavily than a similarly sized round without sector-relevant strategic validation.
- North America remains the deepest capital market for LDES even when its share fluctuates. Europe and Asia-Pacific can produce credible companies, but the largest equity checks still cluster disproportionately in North America.
- Europe’s 2025 improvement was real but not yet equivalent to North American capital depth. Europe gained deal count and capital share, but its low median deal size means Europe’s LDES ecosystem still looked more like a technical and institutional validation market than a scale-capital market.
- Asia-Pacific appears strong in selective companies rather than broad funding depth. RayGen, VFlowTech, H2, Allegro, Green Gravity, and Meine Electric show activity, but the region’s typical round size remains much lower than North America’s.
- Electrochemical LDES should not be treated as a single homogeneous category. Iron-air, nickel-hydrogen, vanadium flow, organic flow, zinc-air, zinc-bromine, and acid-base flow systems have very different scaling paths, capital needs, and deployment risks.
- Mechanical storage is increasingly financed like infrastructure, not like ordinary venture hardware. Hydrostor, Highview Power, Energy Dome, and Sizable Energy point toward project-development and asset-heavy funding models rather than classic software-style venture scaling.
- Behind-meter LDES is becoming more strategically interesting because it can attach to urgent power constraints. Data centers and industrial customers may pull LDES adoption forward faster than slow utility procurement cycles.
- Thermal-to-power needs careful filtering. Several thermal storage companies raise money for industrial heat or steam decarbonization, but those rounds should not be counted as LDES unless the system is clearly procured and operated as electricity storage.
- Repeat funding is one of the strongest signs that an LDES company is becoming durable. EnerVenue, RayGen, Exowatt, ESS, and several other repeat raisers matter because they show continued investor willingness to fund the same platform beyond a first proof point.
- The investor market is not yet standardized. Repeat backers exist, but the list changes from year to year, which means most LDES financings still look like company-specific judgments rather than automatic category allocations.
- The strongest future LDES companies will probably combine technology credibility with a financing model that matches the asset. Batteries, compressed air, liquid air, gravity, thermal storage, and behind-meter systems do not need the same kind of capital stack.
- The cleanest screening rule for future deals is to require duration, electricity-storage use case, pure-play exposure, and capital purpose. Deals that only mention renewable heat, recycling, geothermal firm power, grants, debt, or project finance should be discounted unless they clearly meet the 10-plus-hour electricity-storage-system definition.
This chart, included in our LDES market deck, shows how iron flow battery storage technology has evolved over time
OUR METHODOLOGY TO BUILD THIS TRACKER
We built this LDES funding tracker by reviewing every publicly disclosed equity round raised by pure-play long-duration energy storage companies between January 2024 and May 2026. A company counts as pure-play when more than 80% of its activity is dedicated to electricity storage systems designed to discharge at rated power for at least 10 hours.
We applied four filters to build the dataset. First, we only included equity rounds, so grants, debt, structured financings, project finance, acquisitions, SPAC transactions, and business combinations are excluded. Second, we only counted rounds of $300K or more. Third, we only kept pure-play LDES companies, which means we excluded short-duration storage, demand response, industrial heat systems not operated as electricity storage, hydrogen or fuel value chains, battery materials, recycling, software-only optimization businesses, and geothermal or firm-power companies that do not meet the 10-plus-hour electricity-storage definition. Fourth, every entry had to be confirmed by a direct company announcement, press release, tier-1 media report, specialized energy-storage source, or relevant regional publication.
Undisclosed-amount rounds are excluded from dollar-based metrics because including them would distort averages, medians, category shares, and concentration ratios. In 2025, Energy Dome is counted in deal and company counts because the strategic investment was reported, but it is excluded from disclosed capital calculations because the amount was not public.
We used the announcement month and year for timing, except where the source explicitly indicated a financing was finalized in the relevant period. Every average, median, share, and concentration ratio is computed only on the qualifying disclosed sample. Privately raised rounds, undisclosed extensions, and financings hidden inside corporate balance sheets are necessarily missing, which is a known limitation of any public-only LDES funding tracker.
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