Arguments
The coolest new energy storage technologies
Posted on 13 August 2025 by Guest Author
This is a re-post from Yale Climate Connections by SueEllen Campbell
Solar and wind energy systems require some means of saving power for times when the sun doesn’t shine and the wind doesn’t blow. Such approaches, from batteries to gravity, are developing rapidly and in many different directions.
The pieces below sample the richness and complexity of this important topic.
Batteries
It can feel impossible, at least for a nonspecialist, to stay current on research into new kinds of “regular” batteries, never mind those suitable for large-scale energy storage. One fairly promising recent development is the iron-air battery – or, we might say, rust. See “How iron-air batteries could fill gaps in renewable energy” (Alissa Greenberg, NOVA) for an engaging and thorough introduction.
For a good overview of the energy storage situation at the end of last year, focused on batteries collected to act at grid scales, read “2024 was a fantastic year for energy storage” (Julian Spector, Canary Media). Another encouraging overview is this one by Oliver Milman in the Guardian: “U.S. power grid added battery equivalent of 20 nuclear reactors in past four years.”
Hydrogen
Hydrogen gas can be produced with excess clean energy (“green hydrogen”) and stored until it is needed; then, mixed with methane, it is burned to create more energy, creating less pollution than methane (or “natural gas”) alone. For a pair of stories about one such project, see “A huge underground battery is coming to a tiny Utah town” (Henry Fountain, New York Times) and “Hydrogen is transforming a tiny Utah coal town. Could its success hold lessons for similar communities?” (Emma Penrod, Utility Dive).
Gravity: water
“Pumped hydro” storage requires two water reservoirs at different elevations. When power is abundant, water is pumped uphill; when it is needed, it flows downhill through turbines, creating usable electricity. For the surprisingly large number of large-scale facilities of this type, many of them in China, see this Wikipedia article: “List of pumped-storage hydroelectric power stations.” And for an underground version, see “Revolutionary new Swiss ‘water battery’ will be one of Europe’s main renewable sources of energy” (Rebecca Ann Hughes, Euronews).
Gravity: other weights
Of course, it’s not only water that can be moved upward and released downward; weights are easy to find, and other kinds of vertical distances are starting to interest battery innovators. Elevators in very tall buildings, for instance: “Researchers propose turning high-rises into gravity batteries” (Prachi Patel, Anthropocene). Old mine shafts: “Abandoned coal mines are becoming the batteries of the future” (Natasha Khullar Relph, Reasons to Be Cheerful). Even simple train tracks up hillsides: “The train goes up, the train goes down: a simple new way to store energy” (David Roberts, Vox). (It’s not clear whether this project still exists, though the company seems to.)
Thermal
Several types of thermal energy storage are being explored. One is “sensible heat storage” – simply heating and cooling some kind of material. For instance, sand batteries in Finland: “How a sand battery could transform clean energy” (Erika Benke, BBC) and “A tiny town is betting on a sand battery to heat homes. It could revolutionize energy” (Tim Newcomb, Popular Mechanics).
Another involves pumping water deep underground to make use of fracking technology, geothermal heat, and water pressure, as in “This Texas geothermal startup is storing energy in the ground” (Maria Gallucci, Canary Media). As is usual in Canary Media stories, this one is quite thorough, a little bit technical, and mentions other related experiments.
For more
To learn about other types of energy storage – and the varied ways they are categorized – see “The different types of energy storage and their opportunities,” Jonathan Spencer Jones, Smart Energy International, or “An overview on classification of energy storage systems,” Mohanraj Kandhasamy et.al., ACS Publications (American Chemical Society).
Nice summary of the many existing and developing methods of storage excess renewable energy for use when the renewable generation is less than the demand.
A minor clarification is required regarding the presentation on Hydrogen. The planned project in Utah is better than the way it is summarized. The project in Utah is intended to ultimately burn pure Green Hydrogen, as explained in “Hydrogen is transforming a tiny Utah coal town. Could its success hold lessons for similar communities?” (Emma Penrod, Utility Dive):
"Because the original IPP plan called for the construction of two additional coal units that were never built, the cooperative had room on site for a new set of generators — two natural gas units totaling 840 MW. These will start running a 30% hydrogen blend as early as this summer, with a goal of using 100% carbon-free hydrogen by 2045.
I would add one more important point that seems to always be missed when discussing the future of renewable energy systems. There is something that can happen immediately, needing no new technology or systems to be developed or built.
The transition to a net-zero climate impact energy system will happen quicker and produce less total harmful impact if people who currently are over-consumers of energy rapidly transition to living without the excessive 'convenient and enjoyable' but unnecessary energy use.
If the qualities attributed to solid state Lithium batteries are ever realised, (possibly this decade?) then surely battery storage will become the most efficient and least expensive way of maintaining grid stability. Battery storage also ensures that waste of solar/wind energy is minimised.
Can any other forms of storage compete with batteries?
Australia has convincingly demonstrated that water storage is not an option because it is so massively more expensive than batteries.
Fire seems to be the main concern with lithium type batteries. A 200Mw battery storage project was proposed in my rural Ontario municipality, but was almost unanimously rejected by residents because of fear of fire.
Regarding the fire concern leading people to oppose utility scale lithium battery storage systems as mentioned by John Wise @3.
Th following is one evidence-based presentation indicating that utility scale lithium battery units are quite safe.
Claims vs Facts: Energy Storage Safety
It seems likely that untrustworthy people opposed to renewable energy - fossil fuel fanatics - deliberately misled people regarding the risk. That happens a lot because too many people are too easily impressed by skilfully developed misleading marketing.
John Wise does not provide a link to explain exactly what storage project was rejected in his Ontario municipality, but Ontario overall is going ahead with a number of storage projects. The following link discusses an RFP (Request for Proposals) that has resulted in "...contracts with 13 selected proponents, acquiring 2,194.91 MW of new capacity scheduled to come into service between 2026-2028."
https://www.ieso.ca/Sector-Participants/Resource-Acquisition-and-Contracts/Long-Term-RFP-and-Expedited-Process
The RFP page above does not talk directly about the storage technologies, but if you follow the link labelled "E-LT1 RFP" in the paragraph under the grey box, it leads to the following PDF. In that PDF, several of the selected suppliers refer to battery technology.
https://www.ieso.ca/-/media/Files/IESO/Document-Library/long-term-rfp/ELT1-RFP-Selected-Proponents.pdf
Aside from re-using LI batteries from EVs, I suspect fire-prone NMC batteries will quickly disappear from stationary storage. LFP batteries are far safer, last longer. Other chemistries are advancing rapidly. With a stationary battery, weight and volume are not such big issues. NaS batteries are already in use and Na-ion is progressing quickly.
I am intrigued by salt hydrates for thermal energy storage. Energy is stored and released with the reversible thermochemical reaction for heat of hydration. Just add water.
K2CO3 + H2O ↔ K2CO3•1.5H2O + heat
Ref: Gaeini, Shaik, and Rindt, “Characterization of potassium carbonate salt hydrate for thermochemical energy storage in buildings,” Energy and Buildings, Elsevier, Aug 2019
John Wise says "A 200Mw battery storage project was proposed in my rural Ontario municipality, but was almost unanimously rejected by residents because of fear of fire."
It goes to show that fear is a great lever to manipulate people's perceptions. It also shows that modern ways to disseminate information are the most important mean to control and manipulate said perceptions, and therefore people. The fact that it was "almost unanimously" rejected suggests that virtually nobody applied critical thinking to the question.
If the town had been asked the question about a natural gas pipeline or plant, would there have been a similar consensus about fire risk? If these same town folks were asked about EV fires, would they tend to overestimate the risk compared to ICE car fires? Fire remains a significant safety concern in vehicles carrying over 100 liters of highly flammable liquid but are people worried about it? How is their perception formed?
There are parts of rural Ontario that have also voted against wind turbines.
We recently had an EV charging station installed at our house (in Ontario). The Electrical Safety Authority is pretty serious about inspecting such installations (which require a permit), as they have been running into a lot of poor quality installations. The high amperage (ours is 40A) is similar to that of a clothes dryer or kitchen range but it often can run for hours on end. The risk of overheating is higher - but manageable by proper installation.
The fear that Phillippe mentions probably also does not extend to house fires caused by electrical faults - nobody is calling for electricity-free communities to prevent such fires.
Near us there are new suburbs being built that have long linear sections of open land that look a lot like parkland. To most residents, it probably looks like a nice, wide boulevard that is much wider than you would think was needed for that road. Very few are likely aware that it is a major pipeline route. The developers could build houses on either side of the pipeline ROW, but not directly on top of it. I'll bet that if the houses were built first, and then the energy company applied to build the pipeline through the middle of the development, the residents would have voted against that, too.
A bit of visual evidence to support what I said in the last paragraph of comment 9.
Google Earth images of an area west of here. First image is from 2007. The path of the existing main trunk pipeline can be seen as a slight variation in vegetation colour running from the lower left of the image to the upper right.
Most recent image shows the wide boulevard in the middle of the housing development, along the pipeline route.
Buyer beware.
Philippe Chantreau @8 :
The forming of perceptions is indeed crucial in democratic governance. An equally important factor is the final process of decision-making.
The ancient Greeks had problems with the way that the citizens gathered in the agora would easily flip-flop in their decision-du-jour, depending on the day of the assembly and the rhetoric of the best speaker that day.
In modern times, the UK Brexit decision was made "poorly". #A few years ago, I heard an excellent speech by a British Lord Someoneorother, to the effect that Brexit would have been avoided if the decision-making had been left to the elected Members of Parliament. His point was that ~ though often imperfect ~ we are rather more likely to get a "good" decision on any topic, when the discussions get slowed down to a gradual pace (through committees, compromises, "horse-trading", and cooling-off periods, and even the receiving of expert advices! ). In other words ~ using Representative Democracy instead of plebiscites.
As Bob Loblaw shows, it's difficult to balance NIMBY + reasonable.
The issues of EV's lithium batteries catching fire. I wonder if this battery issue explains some of the slowing of EV sales recently. This battery issue has been in our media over the last few years. What gets lost in the fine print well down the commentary is EVs are less likely to catch fire than ICE cars, and that the fires are generally where a battery has been damaged in some way, perhaps a crash. Sometimes people only read the headlines and first couple of paragraphs.
I agree with Eclectics comments on the downsides of referenda. The public just don't know enough about economics to make a sensible judgement on something like Brexit. However I do think referenda have their place for contentious social issues and if changing something like a constitution. These issues are easier to evaluate. Eg things like gay marriage, when people should be able to vote, drug legalisation. Of course you still get misinformation on such issues, the scourge of our internet age.
Nigelj @12 :
An anecdote ~ just this week, my neighbours bought a new EV. It's fine looking car, sleek and stylish, with an 80 KWh battery of the NMC type. Their first EV. I gather that they had given scant consideration to NMC fire risk compared to the safer LFP type of battery.
My impression is that the fire risk is of small thought to much of the EV-buying public. As to the EV-avoiding purchaser ~ I can only go on impressions, rather than on good survey data, about their criteria & motivations. There are so many other plusses & minuses influencing EV decision taking.
I agree with Phillipe that people want to think about the gasoline in their cars before a possible fire in an industrial setup out of town. What about the 50,000 liter tankers they drive besi on the road? These tankers get in accidents every day and catch on fire at a higher rate than a battery bank.
I thought fire in Lithium-ion batteries was was caused by short-circuit resulting from growth of dendrites - so the older a battery the more likely the risk of fire. This risk had been significantly reduced by including sensors in each battery cell which detects risk of short-circuit, isolates the cell and warns of the defect. The ‘fire’ problem has been significantly reduced - except in older batteries manufactured before these sensors were introduced.
Laboratory work on solid state Lithium-ion Batteries shows that replacement of the liquid buffer between cathode and anode with a solid one eliminates the risk of fire. It also shows that Solid State Lithium -ion batteries also have the following advantages over batteries presently in use:
These make commercial development of solid state batteries an all important goal but one which is fraught with manufacturing com plexities which have yet to be overcome and which could increase battery price.
Could AI have a role to play on overcoming design and manufacturing problems?