Have You Felt the Power?
One of the most frustrating first-world problems any of us deals with on a daily basis is the low-power device. Whether it’s a cell phone, mp3 player, laptop, or any one of the many portable electronics we tote around with us all day, that blinking battery icon will send even the most stoic among us sprinting for the closest outlet.
There are many people working on this problem, with just as many possible solutions. One of the most obvious is to create devices with a longer battery life. However, this is much easier said than done, as we have reached the limits of what can be done with our current battery technology. Longer-lived batteries are possible to make, but they are too expensive to be practical for now.
The optimal solution would be to create device that doesn’t need a stored power supply at all. In theory, such a design is possible, as there is plenty of energy all around us all the time; the trick is accessing that energy. Sunlight is the most obvious form of renewable energy; we are all familiar with solar panels and their potential to power small electronics. It’s almost impossible to buy a calculator these days that doesn’t have a line of solar panels along the top, but unfortunately, this technique is not practical for more power-hungry devices.
Researchers from the Center for Nanotechnology and Molecular Materials at Wake Forest University have taken another approach altogether. They have created a fabric that generates electricity from temperature differentials. Clothing could be made from this material; body heat on the inside and room temperature air on the outside would create the needed temperature differential and generate electric current. Named “Power Felt” by its creators, the fabric is composed of carbon nanotubes interwoven with plastic fibers that work together to harness power through the thermoelectric effect. Head researcher David Carroll explained the process like this: “if you grab a piece of metal at one end with your hand, you warm it up. The electrons there become warm and move rapidly. Many of those hot electrons move away from the heat to settle in the cooler regions of the material. The difference in the number of electrons in the warm region and the cool region is what give the voltage that is used to create power.”
Other attempts to create fabrics that generate electricity have relied on wearable solar panels, or the piezoelectric effect. Tokyo-based company Ideal Star has even created weavable threads that harness solar energy, however these threads have only a 3% efficiency, much lower than the 15-20% of conventional solar panels. Currently the fabric is expensive to produce, although mass production may reduce the cost. Over at Berkeley, researchers have created nanofibers that can be woven into conventional clothing that generate energy. These fibers have piezoelectric properties, which means they generate power as they bend and flex, but are not able to generate enough power to be practical as yet.
By utilizing temperature differentials to create power, the researchers at Wake Forest University have not only created cost-effective, practical fabric that meets the needs of our mobile technology, they have opened to doors to generating power from all sorts of waste heat. They envision integrating their Power Felt anywhere there is a temperature difference: around hot water pipes, underneath roof shingles, in car seats, medical monitors – the possibilities are nearly endless. What’s more, they plan to get the price down to about $1 for a piece the size of a cell-phone cover. Investors are already interested, and it looks like this fabric may be soon hitting the stores. Hopefully, by the next time your phone runs out of power, all you’ll have to do is plug it into your shirt.