Pumped hydropower, flow batteries and industrial heat batteries already have operating projects. Their applications differ, from supplying electricity to delivering steam for industrial processes.
For businesses considering energy storage, the choice depends on the service required, the duration of supply and the evidence from installations operating under comparable conditions.
Start with the job the storage system must do
Power and energy describe different capabilities. Megawatts measure the rate at which a system can deliver power; megawatt-hours measure the quantity of energy stored or delivered. A hypothetical system supplying 10 MW for four hours would deliver 40 MWh. That calculation alone says nothing about its efficiency, cost or usable lifetime.
Duration matters too. The US Department of Energy defines long-duration energy storage as systems capable of delivering electricity for at least 10 hours. A technology suited to that task may answer a different need from one designed for short, frequent bursts.
Pumped storage provides an established reference point
Pumped storage hydropower stores energy by moving water to an upper reservoir. When electricity is required, water flows down through turbines; pumping restores the stored energy for another cycle.
The Department of Energy describes pumped storage as a well-established commercial technology. Its commercial history provides a reference point for newer storage technologies.
For a proposed project, the practical questions should concern the actual site, construction requirements and operating role. Comparing an established reservoir scheme with a new battery solely by storage capacity would overlook much of what determines whether either is suitable.
Flow batteries have operating projects to examine
Vanadium flow batteries are another technology with examples beyond laboratory testing. In a 2023 announcement, manufacturer Invinity reported that an 8.4 MWh system at the Chappice Lake solar and storage project in Alberta had begun operating.
That is evidence of deployment, although a supplier announcement is not an independent assessment of lifetime performance. The next questions are more demanding: how much energy does the installation deliver, how often is it available, and what maintenance does it require?
For buyers, several years of relevant operating data would be more useful than a headline capacity figure alone. Evidence from one installation should also be assessed against the conditions of the proposed next project.
Thermal storage serves a different market
Some storage systems supply industrial heat rather than returning electricity to the grid. In October 2025, Rondo reported that its 100 MWh industrial heat battery at a California facility was operating automatically each day, using on-site solar electricity to support continuous steam production.
The distinction matters: a thermal storage capacity cannot be compared directly with an electrical battery capacity as though both deliver the same product. For an industrial customer, the relevant output may be steam at the temperature, pressure and reliability its process requires.
Three different decisions for storage buyers
A grid operator looking for electricity after sunset needs to know the required power, the number of hours of supply and how the store will recharge. An industrial site looking for steam needs to specify the heat output its process can accept. These are different purchasing decisions, even when both projects use electricity to charge.
Consider a hypothetical requirement to supply 5 MW for 12 hours. That represents 60 MWh delivered over the period. A storage capacity of 60 MWh on a specification sheet would still need checking against the usable output, operating limits and losses stated for that system. The calculation defines the requirement; it does not establish that a particular product meets it.
For a steam user, the equivalent starting point is its heat demand and operating schedule. The Rondo example concerns an industrial heat service, while Chappice Lake concerns electricity storage alongside solar generation. Their announced capacities describe projects serving different needs.
Compare the evidence, as well as the technology
| Approach | Example or evidence | Question for a prospective user |
|---|---|---|
| Pumped storage | Established commercial electricity storage | Can the proposed site and scheme supply the required power and duration? |
| Vanadium flow battery | Invinity reported operation at Chappice Lake in 2023 | What operating record supports the proposed duty? |
| Industrial heat battery | Rondo reported daily operation at its California installation in 2025 | Does the heat output meet the industrial process requirements? |
The commercial assessment should use the same system boundary for each option. An equipment price cannot be compared fairly with a price that also covers installation and maintenance. A buyer needs a defined service and a consistent cost breakdown before the alternatives can be ranked.
What would demonstrate readiness for wider deployment?
A useful assessment begins with the project’s status. Is it announced, under construction, commissioned or operating routinely? It should then examine measured output, the period covered by the results and the conditions under which testing took place.
Commercial questions belong alongside technical ones: what does the complete installation cost, who maintains it, and what happens when components need replacing? The answers determine whether a system can meet a customer’s requirements over its working life.
Innovation News Network’s wider guide to emerging technologies explores innovations across multiple sectors. For energy storage buyers, the decisive evidence is sustained performance: how reliably a system supplies the electricity or heat their operation needs.
