Nobody likes power cords, and batteries always need recharging or replacing. What if your device could run on only the power it could gather together by itself from the world around it? It would be almost like free energy, although without breaking the laws of physics.Hackaday’s 2026 Green-Powered Challenge asks you to show us your devices, contraptions, and hacks that can run on the power they can harvest. Whether it’s heat, light, vibration, or any other source of energy that your device gathers to keep running, we’d like to see it.The top three entries will receive $150 shopping sprees courtesy of the contest’s sponsor, DigiKey, so get your entry in before April 24, 2026 to be eligible to win.Honorable MentionsAs always, we have several honorable mention categories to get your creative juices flowing:Solar: In terms of self-powered anything, photovoltaic cells are probably the easiest way to go, but yet good light-harvesting designs aren’t exactly trivial either. Let’s see what you can run on just the sun. (Or even room lighting?)Anything But PV: Harnessing the light is too easy for you, then? How about piezo-electric power or a heat generator? Show us your best self-powering projects that work even when it’s dark out.Least Power: Maybe the smartest way to make your project run forever is to just cut down on the juice. If your project can run on its own primarily because of clever energy savings, it’s eligible for this mention.Most Power: How much of a challenge is building a solar-powered desk calculator in 2026? How about pushing it to the other extreme? Let’s see how much power you can consume while still running without batteries or cords. Does your off-grid shack count here? Let’s see it!Prior ArtWe’ve seen a lot of green-powered projects on Hackaday over the years, ranging from a solar-powered web server to a microcontroller powered by a BPW34 photodiode. Will your entry run off the juice harvested by an LED? It’s not inconceivable!Solar cells only work when the sun shines, though. As long as your body is putting out heat, this Seebeck-effect ring will keep on running. (Matrix vibes nonwithstanding!) Or maybe you want to go straight from heat to motion with a Stirling engine. And our favorite environmental-energy-harvester of all has to be the Beverly Clock and it’s relatives, running on the daily heat cycles and atmospheric pressure changes.Your TurnSo what’s your energy-harvesting project? Batteries are too easy. Take it to the next level! All you have to do to enter is put your project up on Hackaday.io, pull down the “Submit Project to…” widget on the right, and you’re in. It’s that easy, and we can’t wait to see what you are all up to.And of course stay tuned to Hackaday, as we pick from our favorites along the way.