sierraclub.org - sierra magazine - may/june 2013 - innovate: wearable watts!
By David Ferris
Inclement Energy
As a boy, Elias Siores cavorted on Greece's sun-splashed shores and played water polo and kayaked in the Gulf of Corinth. Siores, 50, now huddles in Bolton, England, northwest of Manchester, where more than two inches of rain can fall in June.
The inclement weather weighed heavily on Siores's mind when he moved to England to head the University of Bolton's Institute for Materials Research and Innovation, which is known for its breakthroughs in textile design. He wanted to join the renewable energy revolution, and even in the gloom of England he saw a glimmer of opportunity.
Siores is a chemical engineer who got his Ph.D. creating sensors that are activated by pressure, vibration, or movement, an area of energy production known as piezoelectrics. He is among a small cadre of scientists around the world who are trying to fabricate slender and flexible fibers that create electricity and can be woven into fabrics. Some scientists are working on piezoelectric fibers, while others are working on solar ones. What if, he wondered, we could combine the two, providing renewable energy rain or shine?
Siores says he and his team have field-tested a thread code-named "RED Fibre" (see above). At its core is PVDF, a widely used specialty plastic. Through the application of heat, pressure, and high voltage during the manufacturing process, it becomes piezoelectric—and thus can generate an electric current when it moves.
Surrounding the PVDF core are layers of photovoltaic material and copper (or other electrode materials), which together create an electrical circuit. An eight-inch-square cloth made of Siores's fiber could pump out a watt—almost enough to charge an iPod—when it's sunny (for maximum solar power) and windy (for piezoelectric efficiency).
The fiber could be woven into sails, tents, bags, jackets, and shoes. Siores imagines that one day these multisource generators could form a solar farm composed of artificial trees. Solar power would flow during sunny days, and piezoelectric power would be generated during rainstorms and windy nights. In other words, the fiber would be active in every kind of weather, kind of like Siores himself, who escapes the U.K. gloom by swimming an hour each day in an indoor pool and by fleeing to Greece whenever he can to bask in the sun of his homeland.
Illustrations: Brown Bird Design