Claim:
Japanese researchers at Kyoto University announced in December 2025 that they invented a coin-sized generator that creates 24/7 electricity “out of thin air.”
Rating:
In December 2025, Facebook users shared a post (archived) that claimed Japanese researchers at Kyoto University “invented a tiny, coin-sized generator that creates electricity from thin air.” The generator, according to the post, harvested energy from humidity to generate electricity 24/7 with no moving parts. The generator had been successfully tested for months in rice paddies in Southeast Asia, the post claimed.
A similar claim was posted to Instagram (archived) a week prior. Various versions of the claim were frequently shared across Facebook (archived) for months (archived) before the more recent posts, with Snopes finding at least one such post (archived) dating back to August 2025.
Japanese researchers at Kyoto University have invented a tiny, coin-sized generator that creates electricity from thin air.
The device uses a special layered nanofilm to absorb water vapor from the atmosphere and convert it into a steady electric current.
Unlike solar or wind power, this generator works 24 hours a day, indoors or outdoors, without needing sunlight or wind.
It has already been successfully tested in rice paddies in Southeast Asia, powering sensors for months.
With no moving parts and the ability to work anywhere with humidity, it offers a durable, clean energy solution for remote locations.
This claim, while loosely based on real research, was not true.
Snopes searched for evidence of the claim using several different Google searches, including “kyoto university humidity generator,” “Moisture-electric generators kyoto university” and “kyoto university coin generator” and could find no research or reporting on such an invention from Kyoto University. Snopes also searched “generator rice paddies southeast asia” to look for evidence of the practical application of the technology as mentioned in the social media posts, but could find nothing aside from social media posts spreading the claim.
What Snopes did find, however, was 2025 research from Kyoto University on cells for solar power and a number of research papers about devices similar to the one described in the social media posts, which Snopes found through a Google search of “Moisture-electric generators.” The bulk of research on the subject from the past couple of years appeared to be led by researchers affiliated with Chinese universities and laboratories.
Moisture-electric generators are designed to produce energy from humidity by taking advantage of the same properties of water droplets that lead to lightning within clouds, according to a 2023 article from Science News Explores, a science magazine geared towards students and educators. At that time, the power output of the devices was too tiny to be used practically.
Many of the research papers from the earlier search focused on the potential use of different materials to boost the generators’ efficiency. A project funded by the European Union similarly seeks to improve upon the technology to make it feasible.
In August 2025, Popular Mechanics reported on a related device, a generator designed to produce electricity from evaporation, that the magazine said “transforms moisture from the air directly into electricity—no moving parts required.” However, Popular Mechanics reported that even this device needed to be more efficient before it could start to be used practically.
Regardless of the science, the social media posts spreading the claim about the Kyoto University generator included hints the claim was false within their text. Several of the posts (such as this one) claimed the Japanese researchers’ generator was “matchbox-sized,” despite showing what appeared to be an AI-generated image of a device shaped like a coin.
The contradicting image and claim posted by Factify in the link above appeared to originate from an Aug. 30, 2025, post (archived) from another page that peddles fake or overhyped feel-good scientific discoveries. A watermark appears to be blacked out in the top right of the image Factify posted with the claim, which is the same location in which there’s a watermark with the logo of the Facebook page that posted the Aug. 30 version.
But the claim appeared to originate from even earlier in the month, at least as far back as Aug. 4, when another such Facebook page posted (archived) about a Japanese moisture-powered generator “smaller than a matchbox” and “the size of a coin.” Many of the details of the later posts appeared to be based on those from this older post, which even included AI-generated images of the Southeast Asian rice paddies in which the technology was supposedly field-tested.
For further reading, Snopes has previously fact-checked other claims shared by Facebook pages specializing in science slop.
