E-glass—already a workhorse reinforcement for fiberglass composites used for everything from shower doors to printed circuit board platforms to boats to storage tanks, and more—may turn out to be the material of choice for a high-tech energy storage system.
Efficient conversion of alternative energy sources, such as wind or solar, is one piece of the problem. The second piece of the problem is storing the energy collected from these cyclic sources until it is needed. With justification, much of today’s energy storage research focuses on batteries of all types: lithium-ion, flow, air, and good old lead acid.
However, there are clever minds working at developing flywheel technology for energy storage. Flywheels work like motors in reverse. Motors draw power to make a shaft and its components turn. An efficient, spinning flywheel can pump power as it slows down.
Flywheels have to durable because of the enormous centripetal force that can be generated. Existing power grid-scale flywheels are made of carbon fiber composites, but a flywheel technology built around E-glass fiberglass is in development, thanks to an infusion of Kickstarter funds.
Bill Gray, founder of Velkess Inc., concedes that carbon fiber polymer composites are six to eight times stronger than E-glass composites. However, according to a phys.org press release, he says that E-glass composite is 10-20 times stronger per dollar and that it will store 10-20 times more energy per dollar.
The company’s Kickstarter webpost says that the key to reducing the cost of flywheels is to use materials that are flexible. Traditional flywheels, Gray says, are made of rigid materials and require expensive, precision machining. Velkess (VEry Large Kinetic Energy Storage System) turned to an E-glass composite design. They say the “flexible system embraces the natural dynamics of the rotor, redirecting any stray energies into stabilizing counter forces. By working cooperatively with these natural rotor dynamics we gain excellent control of the rotor system without having to crush out its irregularities.”
The video on Kickstarter (be ready for the “ask” toward the end) shows the company’s prototype 25-pound flywheel, which it says can store 0.5 kWh of energy for 2 kW of power. The goal is to scale-up to a 15 kWh energy storage capacity, which will require a flywheel weighing about 750 pounds. Apparently, the operation of these things is like running a jet engine sans exhaust fumes. The writer of the phys.org press release speculates that reaching the target of storing 15 kWh of energy will require a flywheel RPM similar to the RPM of a jet engine, which is much higher than the fastest available electric motor speeds.
The company sought $54,000 to scale-up the magnetic bearing system to handle the 750-pound flywheel rotor and raised $56,162. Where mechanical bearings are used, they are made of silicon nitride. Thermal sensors can be built into the system to trigger a shutdown if the internal temperature rises, which could indicate the possibility of an imminent bearing fracture.
Gray expects that flywheel systems will cost about the same as lead acid batteries, but that they will last much longer, with much lower environmental cost.