This yarn might not make the best sweater, but when pulled, it does something even better: It generates electricity. An international team of scientists made the new material, called “twistron harvesters,” by tying a carbon nanotube string into a tangled weave of carbon and submerging it into an electrolyte gel. When covered in the gel and pulled, the carbon nanotubes squeeze together and generate a small current—enough to momentarily light up a light-emitting diode (as you can see in the video above). The researchers found that the twistron could harvest power directly from ocean waves or—when sewn into a shirt—from the wearer’s breathing motion, they report today in Science. More power can be generated if the harvesters are hooked up together, with peak power generation reaching 250 watts per kilogram. Because of their scalable nature, the researchers say these carbon nanotube yarns could be used anywhere reliable kinetic energy is available.