Battery-free power for maritime sensors and navigation aids
January 20, 2026 – Researchers at the National Renewable Energy Laboratory (NREL) have developed a generator that can generate electrical energy without batteries, exploiting small temperature differences between seawater and the air above it. The so-called thermomagnetic generator uses the temperature difference between the ocean and the ambient air above the water. The model developed by NLR uses gadolinium, a rare earth metal known for its magnetic properties at room temperature. This type of generator uses the difference between warm ocean water and cooler air to continuously cycle a magnetic element between magnetic and non-magnetic, generating electricity. In a laboratory setup, a prototype generated enough power to power wireless maritime sensors at a temperature difference of less than ten degrees Celsius. Because the generator is compact and designed to operate even at small temperature differences, it could be suitable for use on ocean buoys and navigation aids that would otherwise rely on batteries.
