Sodium-ion and zinc batteries are getting picked for projects that can’t afford HVAC

A utility-owned zinc battery is headed to a Minnesota campus, and grid-scale sodium-ion is getting productized for the two- to eight-hour segment that lithium dominates. Those aren’t “someday” technology stories anymore. They’re early signals that storage specs are starting to move away from a single default chemistry and toward a more explicit set of operating constraints: cold weather, auxiliary power for HVAC, and what a site can tolerate on fire risk.

Solar Power World reported that the University of Minnesota Morris will install a 1‑MW/6‑MWh zinc energy storage system, using the Eos Z3 platform, with commissioning expected in 2027. In a separate August report, Solar Power World also described how manufacturers are scaling sodium-ion designs quickly and lining up orders, with ESS Inc. planning to release its first grid-scale sodium product next year.

A 1‑MW/6‑MWh zinc system with utility ownership and grid controls

The UMN Morris project is small by utility standards, but it is operationally “real.” Solar Power World said Otter Tail Power will own and operate the Eos Z3 system and connect it directly to the utility’s electrical system. Because it becomes utility infrastructure, the investment went through the Minnesota Public Utilities Commission, which approved it in March 2026, according to Solar Power World.

Two implementation details matter for operators evaluating pilots. First, Burns & McDonnell is providing engineering support for installation, Solar Power World reported. Second, OATI’s GridMind software will manage and optimize dispatch, including charge and discharge decisions based on grid conditions and utility needs, according to the same report. That reduces the “science project” risk by tying an emerging chemistry to established integration and control layers.

UMN Morris also gets something many pilots don’t: time. Solar Power World reported the university will have dedicated research periods across the project’s anticipated 20‑year lifespan to study performance under different operating scenarios. The campus is being positioned as a proxy for a small community, with nearly 1 million square feet of building space and about 1,500 people on campus each day, creating a consistent load shape that’s harder to replicate in a lab.

Sodium-ion’s pitch is temperature range and supply chain flexibility

In Solar Power World’s sodium-ion feature, the core claim wasn’t better batteries in the abstract. It was fewer constraints. The publication described sodium-ion batteries as using abundant, non-toxic sodium and being manufacturable in formats similar to lithium-ion, including same-sized cells and modules. It also reported sodium-ion systems can operate across a wide temperature range, from -40°F to 140°F, without output degradation, which could eliminate the need for HVAC systems in some deployments.

That matters because thermal management is not only a capex line item. It also appears as parasitic load, added controls complexity, maintenance work orders, and additional failure modes. Solar Power World also noted that lithium batteries typically operate best within a narrow temperature range and may require chillers and fans, which can make projects uneconomic in some regions. In cold-weather territories, that HVAC penalty can be the hidden factor driving delivered cost per usable kWh.

Solar Power World framed supply chain as the other motivator, arguing lithium supply chains are dominated by China and that sodium’s lack of critical minerals could, in theory, enable manufacturing to be located in the U.S., Europe, or Australia. For procurement teams, “critical minerals” is often shorthand for contract risk: availability, lead times, and the likelihood of forced substitutions during multi-year buildouts.

The market is still lithium-led, but product roadmaps are shifting

None of this erases lithium’s position. Solar Power World cited International Energy Agency data that lithium-iron-phosphate (LFP) represented 80% of new battery storage worldwide in 2023. In practice, that installed base creates a powerful default: bankability expectations, standard commissioning test plans, and a large pool of integrators with repeatable playbooks.

What is changing is how vendors are trying to meet that default bar with alternative chemistries. Solar Power World reported ESS Inc., a company known for iron flow batteries, will release its first grid-scale sodium design next year. In the report, ESS framed sodium-ion as a way to compete directly in lithium’s common two- to eight-hour applications, while also shifting its flow battery R&D toward 16- to 48-hour discharge. Read as a portfolio move, it suggests a line is forming between “duration as a product category” and “duration as a dispatch requirement,” with different chemistries filling different constraints.

Solar Power World also pointed to early external forecasts. It cited a Morgan Stanley Research estimate that sodium-ion batteries could reach 2% market share by deployment in 2027, then 20% by 2030 and 37% by 2035. Operators don’t need to believe the long-range numbers to use the near-range implication: if sodium-ion hits even low single digits, it will force more EPCs, utilities, and owners to write multi-chemistry standards instead of treating LFP as the only serious option.

On the technology side, Solar Power World reported two sodium chemistries drawing attention: sodium chromium oxide (NCO), positioned as higher energy density, and sodium iron-phosphate pyrophosphate (NFPP), positioned as cheaper to manufacture. That split is a reminder that “sodium-ion” will likely show up in bids as multiple product families with different footprint, weight, and balance-of-system needs.

Where this lands in specs, warranties, and dispatch models

For enterprise energy managers, campuses, and utility operators, the immediate work isn’t cheering for one chemistry. It’s asking what has to change in documents and systems that were written for LFP by default.

• Controls and telemetry: In the UMN Morris project, Solar Power World reported OATI GridMind will manage dispatch. For new chemistries, confirm your EMS can ingest state-of-charge and health signals at the resolution your operating model needs, and that the vendor exposes them contractually, not as an optional dashboard.
• Thermal assumptions in design: Solar Power World’s sodium-ion report highlights a -40°F to 140°F operating range without output degradation. If a project’s enclosure and HVAC were sized for tight temperature bands, rerun parasitic load, breaker sizing, and backup power assumptions. In some sites, reduced HVAC can change net capacity factors and economics.
• Warranty and degradation testing: UMN Morris gets dedicated research periods over an anticipated 20-year lifespan, according to Solar Power World. That is a useful benchmark for operators writing acceptance and ongoing performance tests. Specify what constitutes ‘end of life’ for capacity and power, and how it is measured under cold conditions, not just at nominal room temperature.
• Utility ownership model: Solar Power World reported Otter Tail Power will own and operate the zinc system with PUC approval. For similar pilots, clarify who holds the asset risk, who carries O&M obligations, and which party is responsible for software updates and cybersecurity controls over a multi-decade term.

The next tell will be whether these chemistries start showing up in standardized interconnection and safety packages, or stay boxed into one-off pilots. UMN Morris is scheduled for commissioning in 2027, and ESS has said its grid-scale sodium product is due next year, according to Solar Power World. Those timelines will pressure integrators to build repeatable commissioning scripts and spares strategies sooner than many procurement calendars expect.