Texas A&M researchers say gels packed with cheap hydrated salts can soak up heat by day and release it at night, which could ease the load on air conditioners.
A wall that soaks up the afternoon heat and gives it back after dark could take some of the strain off the air conditioner. Researchers at Texas A&M University say a family of salty gels, called salogels, is one of the more promising ways to actually build it.
The team at the university’s Soft Matter Facility reviewed how these materials have developed, in a paper in ACS Applied Materials & Interfaces that featured on the journal’s 10 June 2026 cover. The university publicised the work on 9 October 2026. Dr Kartik Kumar Rajagopalan, a research scientist at the facility, led the work under Dr Svetlana Sukhishvili, the facility’s director.
The trick is a phase-change material: a substance that soaks up a large amount of heat as it melts and releases that heat again as it freezes, without its own temperature swinging much in between. Ice in a cool box works exactly the same way. Hydrated salts are particularly good at this because they carry water locked physically inside their crystal structure.
The problem has always been that melted salt hydrates tend to leak, separate and break down after repeated use. A salogel solves this by trapping the salt inside a small amount of polymer, a soft network not unlike the one inside a jelly sweet. “Salogels represent a shift from simply storing heat to engineering multifunctional materials that combine thermal energy storage and conversion,” said Rajagopalan. The polymer network also changes how the salt crystallises and helps stop it from “supercooling,” which is when a liquid stays liquid below its freezing point and fails to give its stored heat back on schedule, one of the team’s key earlier findings that this review builds on.
Hydrated salts store considerably more heat per unit volume than paraffin wax, the most common phase-change material used today, according to the review, though the exact comparative figure is worth confirming directly against the paper rather than quoting a round number second-hand. Salogels made with reversible chemical bonds keep 80 to 95 per cent of the pure salt’s original heat-storage capacity. Older ways of holding the salt in place, such as porous supports and capsules, limit it to under 70 per cent of the material’s potential. One example salt, calcium chloride hexahydrate, happens to be a by-product of making soda ash, which keeps the raw material genuinely cheap.
Paraffin wax remains the phase-change material most often used in building panels today. In the same volume, it stores meaningfully less heat than a hydrated salt does, according to the review. For a house, the practical gain is that a thinner layer of material could buffer the same swing between hot days and cool nights, which is heat the air conditioner would otherwise have to remove entirely on its own. The researchers haven’t yet put a kilowatt-hour figure on what that saving would actually look like in a real building.
This is a review of laboratory work, not a product anyone can buy. The open problems here are genuinely serious. Firmer gels store less heat overall, while the softest gels store the most, which creates an obvious engineering trade-off. Some salts stay liquid even after cooling, so heat release sometimes has to be deliberately triggered rather than happening on its own. Humidity protection, manufacturing at real scale, and durability across thousands of heating and cooling cycles all remain unproven territory.
Beyond building uses specifically, the team is also exploring applications in batteries, temperature-control electronics, smart windows, anti-icing coatings, supercapacitors and energy conversion systems more broadly. Rajagopalan said the group’s next steps include improving the mechanical strength of salogels further, reducing supercooling even more, testing 3D printing as a processing method, and applying the material toward electrochemical energy conversion. Funding for the work came through the US National Science Foundation’s Designing Materials to Revolutionize and Engineer our Future programme.
Cooling is one of the fastest-growing electricity loads in India, and the government’s India Cooling Action Plan treats passive building design as part of the answer, though current figures from that plan are worth confirming directly before citing specific numbers. Salogel research already has a direct Indian link: Texas A&M’s earlier announcement of its NSF-funded salogel programme lists Pijush Ghosh of IIT Madras among the collaborators, though his exact role and whether IIT Madras contributed specifically to this review paper would need separate confirmation.
The salts involved here are ordinary industrial chemicals, and India is a significant soda ash producer, so the raw material wouldn’t need to be imported as some kind of specialty product if this technology matured toward real use. The cost and durability questions that remain open in the lab will ultimately decide whether any of this reaches an actual Indian roof.
If salogels survive real summers, they fit neatly into India’s broader push to cool buildings without adding further strain to the evening peak on the grid.
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