U.S. Patent 2,677,664 for a “Composition of Matter for the Storage of Heat” is granted to Maria Telkes.
On 4 May 1954, U.S. Patent No. 2,677,664, titled “Composition of Matter for the Storage of Heat”, was granted to Mária Telkes. This patent focused on the specific materials used to store thermal energy, particularly salts and other substances capable of undergoing reversible phase changes while absorbing or releasing heat.
Telkes’s work identified and optimized phase‑change materials that could store large quantities of heat within relatively small volumes, a crucial requirement for practical solar heating systems. By targeting the composition itself, rather than only the device design, she advanced fundamental understanding of how matter could be engineered for thermal storage applications.
This patent is historically important because it positioned Telkes not only as an engineer of solar devices but also as a contributor to the material science underpinning energy storage. Her compositions helped inform later research on eutectic salts and other storage media used in solar thermal power plants and building‑integrated systems. At a time when women rarely appeared as named inventors on chemical patents, Telkes’s achievement highlighted her technical authority and widened the scope of solar energy research beyond collectors and housings to include the essential materials that make long‑term storage feasible.