Updated on November 13 at 1:11 p.m. PT to clarify and correct technical details.
Big levitated spinning disks will provide electricity to the grid in a project set to begin next month.
Flywheel energy storage company Beacon Power on Tuesday said it plans to begin construction of a 20-megawatt storage facility in Stephentown, N.Y. Provided on a continuous basis, twenty megawatts could power thousands of homes. But flywheels are used only for providing power for short periods.
Rather have many hours of stored energy on standby, the flywheels will store and dispatch bursts of electricity for what's called frequency regulation in the utility industry. Because of fluctuations in power demand, power generators need to deliver power to the grid to maintain a steady signal frequency. Beacon Power's flywheels are designed to provide one megawatt of power for 15 minutes.
George King, supervisor of flywheel assembly at Beacon Power, stands next to the company's 100-kilowatt flywheel.
(Credit: Beacon Power)With flywheels, electrical energy is converted into mechanical energy and stored by the spinning disks. By absorbing electricity and dispatching it for quick bursts of a few minutes, utilities can maintain the frequenc with a system that uses no fossil fuel and responds quickly, according to Beacon Power.
The project will help the utility better use renewable energy that supplies electricity intermittently to the grid, according to the New York State Public Service Commission.
The installation in upstate New York will be the first large-scale use of Beacon Power's technology, according to the company. The Tyngsboro, Mass.-based company secured a Department of Energy loan guarantee in July for $43 million to partially finance the project.
Until now, Beacon Power has operated two smaller 1-megawatt facilities, where 10 flywheels are placed in a shipping container-size structure. The wheels themselves are made of carbon fiber composites, rather than metal, and spin at 16,000 revolutions per minute. To reduce friction, the mechanical components are stored in a vacuum and levitated with a permanent magnet, according to the company.
Another idea that has been pursued by Google for frequency regulation is using networks of electric-vehicle batteries. Rather than dispatch stored energy from batteries, plugged-in cars could have the charge rate throttled back, which a grid management system could use to maintain frequency.
Beacon Power says its latest flywheel will provide one megawatt of storage to the electricity grid by the end of the year.
The company's carbon fiber flywheels, which are one meter in diameter, spin constantly at up to 16,000 revolutions per minute--a surface speed of about Mach 2, Beacon CEO William Capp explained Friday. Each 8,000-pound unit can provide 100 kilowatts of electricity for 15 minutes.
George King, supervisor of flywheel assembly at Beacon Power, stands next to the company's 100-kilowatt flywheel.
(Credit: Beacon Power)Combining 10 of those flywheels will give a utility one megawatt of storage, or 25 kilowatt hours--the equivalent of what a home consumes in a day.
Fifteen minutes of storage may not sound like much, but it's enough to smooth out short-term fluctuations in demand and signal frequency, Capp said.
"These are used for fine tuning to keep everything in balance. The way it's done today is that a dispatcher sends a signal to generators...to increase or decrease output," he explained.
The kinetic energy that's generated from the spinning is converted into electricity when it's needed. Similarly, storage is added to the flywheels by using electricity to make them spin faster.
Utilities are starting to experiment with grid storage as a few technologies start to mature, including flywheels, batteries, and compressed air storage. Storage can prevent outages and store power generated from intermittent sources like solar and wind for times of peak demand.
The next generation of solar thermal power plants will use molten salt to store energy for several hours so that they can continue to meet demand for power after the sun goes down.
Flywheels can react quickly to changes in demand, which is more efficient than bringing power generators up and down, Capp said. He predicted that utilities will invest in them because they help lower their carbon emissions.
"Rather than generating the power using fossil fuels, we'll be recycling the energy," Capp said.
The company intends to combine its 100-kilowatt units into 20-megawatt storage facilities, he added.
You can store energy in chemical batteries. Pentadyne Power stores it in moving objects.
The Chatsworth, Calif.-based company has created and sells uninterruptable power supply (UPS) for data centers and large power consumers that stores energy kinetically. A 25-pound mass spins in a vacuum chamber at a high speed. When a utility needs a jolt of electricity, kinetic power is converted to electrical power. When it's not needed, the mass just spins to conserve its energy.
The company uses a relatively small mass to avoid potential mishaps (imagine what would happen if a large mass came unstuck from its moorings) and efficiency gains can be made through speeding up rotation.
"Kinetic energy equals mass times velocity squared. So doubling mass doubles energy storage, but doubling the rotational speed increases energy storage exponentially," the company's Web site reads.
The mass also levitates on a magnetic field like high-speed trains. This reduces mechanical failure as well as friction. The system has advantages over batteries because, among other reasons, maintenance is lower and the performance does not degrade over time, according to Pentadyne.
Utilities and data centers buy UPSes to keep their own power output level and prevent surges.
The power coming from the company's VSS+dc power supplies does decline from when it first provides energy to when energy is no longer required. That is, it puts out more energy in the first five minutes it is engaged than twenty minutes later. (Batteries do the same thing but generally have longer staying power.) To increase power, utilities can add more power supplies.
Energy storage devices, along with clean coal, are part of a market that is attracting investors but also eluding any easy answers. Conventional batteries improve with performance over time, but not at a regular rapid pace like semiconductors. Utilities are also clamoring for UPS devices because renewable energy sources like solar power fields and wind farms don't produce power at level, regular rates. Thus, everyone is looking for new ways to solve this problem.
Another notable company in the field of UPSes is Deeya Energy, which has a device called a flow battery. In flow battery, new electrolyte flows through the battery and the old stuff moves out, thereby eliminating the charge cycle.
Ben Rosen (who funded Compaq way back when) and Rustic Canyon Partners are investors in Pentadyne.
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