The team created a device that converts absorbed thermal energy into electricity by attaching heat sinks, which take in and release heat, to both ends of a copper cylinder. When one end is placed in the spring water and the other in the air, electrical power is generated due to the temperature difference. Researchers conducted experiments between 2022 and 2023 in Matsumoto, Nagano Prefecture, which has abundant spring water and whose day and night temperatures vary significantly, with the mercury dipping below freezing in winter. They confirmed that electricity was generated, and they could power devices such as temperature recorders. The generated power peaked in January, when the temperature difference was greatest, at an average of 14.5 milliwatts. A regular household uses 6-15 kilowatt-hours a day, and the amount generated from the spring water is minuscule in comparison. Research team member Yasutaka Amagai of AIST's Research Institute for Physical Measurement commented, "It's able to store about one button battery's worth of electricity so that it can be used in water quality management equipment and other such devices. We want to explore how to utilize this technology."