Brooks Sherman on Why Portfolio Thinking Should Replace Single-Technology Bets in Energy Storage Planning

The energy storage market is growing quickly, and the range of viable technologies is widening just as fast. BloombergNEF projects that cumulative global storage capacity will reach 2 terawatts by 2035, roughly eight times the level in 2025. Annual deployments are already hitting record highs, and utilities, developers, and investors are scrambling to make decisions in a landscape that shifts by the quarter. 

For Brooks Sherman, a strategy and business development professional who spent his MBA capstone analyzing next-generation battery technologies, the central lesson is straightforward. Storage planning is becoming a portfolio question, and treating it as a single-technology decision no longer seems to fit where the market is heading. 

Lithium-ion batteries, particularly lithium iron phosphate, or LFP, are dominant today and will remain important for years to come. But the grid’s needs are evolving, supply chain vulnerabilities are real, and new chemistries are advancing quickly enough to change the competitive picture. The planners and investors who’ll be best positioned for the decade ahead, Sherman argues, are those who treat storage not as a product category but as a portfolio problem.

Lithium-Ion Is the Foundation, Not the Whole Building

It’s worth being clear about what lithium-ion does well:

• LFP batteries offer high cycle life, relatively low cost, and a safety profile that has made them the default choice for utility-scale projects. 
• BloombergNEF notes that storage duration is extending to six to eight hours, allowing lithium-ion systems to begin competing with long-duration technologies in some applications. 
• For short-to-medium-duration storage, the technology has earned its market position.

But lithium-ion’s strengths come with well-documented constraints. 

The most pressing issue is supply chain concentration. China controls 80% or more of many key midstream and downstream battery supply chain segments globally. In October 2025, China announced sweeping export controls on lithium-ion battery materials, cells, and production equipment, a reminder that dependence on a single country for a critical energy input carries geopolitical as well as commercial risk.

 Meanwhile, lithium demand rose nearly 30% in 2024, and 74% of global lithium reserves are concentrated in just three countries: Chile, Australia, and Argentina. That’s a lot of supply-chain eggs in a small number of baskets.

Beyond the market constraints, lithium-ion batteries have an unfortunate tendency to overheat and burst into flames, leading to thermal runaway. This can be caused by overheating or even overcharging. 

None of this means lithium-ion is going away. It means that anchoring an entire storage strategy to it without accounting for where it falls short is a planning gap rather than a safe bet.

The Duration Gap Is Where New Technologies Compete

The grid’s storage needs aren’t uniform. A solar-heavy utility might need two to four hours of dispatchable backup. A region prone to multi-day weather disruptions needs something closer to 24 to 100 hours. Lithium-ion handles the first scenario reasonably well. It starts to struggle economically and technically with the second.

That’s why Sherman thinks the duration question is where the portfolio argument becomes clearest. Several alternative chemistries are advancing specifically to fill the long-duration gap that lithium-ion can’t cost-effectively address:

• Flow batteries, particularly vanadium redox systems, offer 10,000+ cycle capabilities and can scale storage capacity independently of power capacity, a key advantage for multi-hour grid applications. They’re not cheap, but their durability makes them worth evaluating for assets with long planning horizons.
• Iron-air batteries are attracting serious attention for 100-hour-plus applications. Form Energy, one of the leading developers in this space, has targeted costs as low as $20 per kilowatt-hour. That’s a level that would make long-duration storage viable for grid planning in a way that changes the economics of renewable integration entirely. The technology uses iron and water as feedstocks, which sidesteps the critical mineral supply concerns tied to lithium.
• Sodium-ion batteries are entering commercial production with approximately 20% lower costs than LFP. CATL, the world’s largest battery manufacturer, unveiled its first platform-based sodium-ion battery designed specifically for energy storage at ESIE 2026 in April, positioning it for commercial deployment within the year. The chemistry relies on sodium, which is one of the most abundant elements on Earth, rather than lithium, offering meaningful supply chain diversification. Additionally, the process of sourcing the components for these batteries is a lot less destructive to the environment than it is with lithium-ion. 

The Portfolio Argument Isn’t About Hedging, It’s About Fit

When Sherman talks about portfolio thinking, he’s not suggesting that every project should buy a little of everything. That would be its own kind of mistake. What he’s describing is a planning methodology: understanding what each technology is actually good at, mapping storage needs by duration and use case, and then selecting technologies on fit rather than familiarity.

A four-hour daily-cycling application at a commercial facility probably still calls for LFP. A utility managing multi-day grid stress events might want to evaluate iron-air. A developer building storage to support AI data center load, a use case that’s exploding in 2025 and 2026, might find sodium-ion’s cost profile and cycle characteristics the right match. These aren’t interchangeable decisions.

The U.S. Department of Energy has estimated the grid will need more than 225 gigawatts of long-duration energy storage by 2050. That’s not a number lithium-ion can address on its own at competitive economics, which means the question isn’t whether alternative technologies will matter. It’s how soon planners will need to understand them well enough to deploy them.

What This Means for Planners and Investors Right Now

Sherman’s background, consulting for a solar and storage developer, writing his capstone on post-lithium market strategy, and working with early-stage tech companies, puts him at the intersection of technology assessment and commercial reality. His read on the current moment is that the window for building genuine literacy in alternative storage technologies is open but not infinite.

A few practical implications stand out. First, supply chain risk needs to be part of the technology evaluation, not a separate conversation. The IEA’s 2025 Critical Minerals Outlook makes clear that lithium, cobalt, and nickel supply risks remain elevated through at least 2027, while geopolitical dynamics, particularly around China’s export controls,  are adding layers of uncertainty that didn’t exist three years ago. Technologies with domestic or distributed feedstocks deserve a real look, not just a footnote.

Second, planning horizons matter more than they used to. A storage asset built today might operate for 20 years. The technology landscape in year 15 will be very different from what it is now. Procurement decisions that lock in a single chemistry without accounting for augmentation, hybridization, or stranded asset risk are making a long-term call while thinking short-term.

Third, the field is moving. At least six manufacturers were expected to launch commercial sodium-ion production in 2025. Iron-air pilot projects are moving into utility validation. Flow battery costs have been declining at 5% to 8% annually. Anyone waiting for these technologies to be ‘proven’ before learning them risks falling behind when the deployment curve steepens.

The Bigger Point: Systems Thinking Over Single-Solution Bias

Brooks Sherman doesn’t position himself as a battery scientist. He’s a strategist and business development professional who thinks in systems. That perspective is exactly what the energy storage conversation often lacks. The tendency to reduce a complex planning question to a simple product preference misses how the technology landscape actually works.

Every storage chemistry has a use case it’s well-suited for and conditions under which it struggles. The planners building toward a $150 billion-plus global storage market by 2030 won’t be the ones who picked the right single technology in 2025. They’ll be the ones who understood the grid’s actual needs by duration, location, use case, and risk profile and matched technologies to them with enough flexibility to adapt as the field evolves.

That’s not a complicated idea. But in a market moving this fast, with this much capital and infrastructure on the line, it’s a discipline worth keeping in view as the market continues to develop.