Imagine a world where instead of burning fossil fuels, we use tiny coiled strings smaller than human hairs but stronger than steel to power all of our smart phones, electric cars, and whatever other gadgets we’ve dreamed up. These strings would generate energy by being stretched and pulled, and therefore could be powered by the rise and fall of ocean waves, vibrations in a factory, and even by your very own breathing. Sounds like science fiction, right? Well, this future isn’t as far out as it might sound. An international team of researchers, lead by scientists at the University of Texas at Dallas and Hanyang University in South Korea, just published a paper in Science outlining the development and use of high-tech yarns, called twistrons, that generate electricity when they’re stretched and pulled.
“We can already make these very small-scale harvesters, about 10-times smaller than the diameter of a human hair, and make them harvest energy,” explained Carter Haines, associate research professor at UT Dallas and one of the co-lead authors of the study. “One of the future goals is doing things like taking a piece of this yarn, tethering it to the bottom of the ocean, with the top... floating on the surface... and creating electricity from the movement of the ocean.”
Wait, But How Does it Work?
“Probably the easiest way to understand these twistron harvesters is: you have a piece of yarn, you make it into a coil structure, you stretch it, and out comes electricity,” said Haines, before going on to clarify that a full explanation of how these twistrons are created and how they generate electricity is a bit confusing. So, if you’re not really interested in knowing how these things work, skip the next paragraph and jump back into it at “simple explanation.”
Explanation: The process starts by creating carbon nanotubes: cylinders of carbon about 10,000 times smaller than a human hair but stronger than the strongest carbon fiber (by weight). Then, in a process similar to the way sheep’s wool is spun to make yarn, these nanotubes are twisted to create carbon nanotube yarns, which Haines and his team have dubbed twistrons. Instead of individual nanotubes, we now have what is essentially the world’s smallest (but strongest) slinky. This tiny, carbon nanotube slinky is then coated or submerged in an “ionically conducting material,” or electrolyte, which could be as simple as table salt and water. The electrolyte fills the yarn with charge. Then, when the yarn is twisted or stretched, the volume of the yarn decreases, bringing the electric charges on the yarn closer together, which results in an increase of energy.
Simple explanation: Physics. It might sound like magic, but it’s not.
Haines pointed out that creating twistrons isn’t cheap, and that the largest barrier the technology currently faces is scalability: it’s simply too expensive to create large-scale twistron systems. Despite these limitations, Haines explained that the technology itself could already be used to power a variety of small electrical gadgets: “These small-scale harvesters can be put in small devices, little sensors...for example if you want different gadgets around your house or in a factory to be connected and be able to send signals to each other (the internet of things), you don’t want to have to go and change the battery on those things all the time... So, imagine being able to put a little harvester in each one of them, and get them to power themselves that way, just from the vibrations in the environment, or temperature fluctuations in the environment”
Haines and his team have already demonstrated that twistrons can be sown into the clothes we wear to generate electricity: as we breath up and down, we stretch the tiny super strong slinky, creating energy. They’ve also shown that twistrons can be placed in the ocean, harnessing the natural movement of the waves to stretch and pull and generate electricity. And because twistrons’ electricity generation could come from any type of kinetic energy, the potential to harvest energy is massive.
Still, Haines was quick to note that there’s a long way to go before twistron energy will be able to rival the scale and scope of fossil fuel giants. “There’s so much energy out there right now, in ocean waves, and lots of people are trying to figure out how to make a good ocean wave harvester, but right now the technologies that are out there are clunky, and don’t scale as well as we’d like them too,” said Haines. “Of course, right now with our technology scaling is also a huge concern, and it’s not the type of thing that is going to be solved in a 2-5 year horizon.”
Still, Haines believes that if the technology continues to be refined and further investigated, these twistron systems could someday become large sources of power:
“What I really hope for is that our technology serves as the start of a platform, that it’ll be a starting off point, and people learn how to scale this technology, how to improve its efficiency. And someday it’ll be able to harvest energy in those types of orders of magnitude that are needed to replace other forms of energy generation.”