FAQs
1. What is a flywheel?
Traditionally a flywheel is a heavy metal wheel attached to a drive shaft, having most of its weight concentrated at the circumference. The wheel resists changes in speed and helps steady the rotation of the shaft where a power source such as a piston engine exerts an uneven torque on the shaft or where the load is intermittent. One of the big improvements James Watt made on the steam engine was to incorporate a flywheel to smooth the load.
2. Where are flywheels used?
In many energy storage applications, but particularly when the need is for ultra-reliable power, or a maintenance-free system (remote areas or to eliminate the cost of maintenance), or when the weather/climate conditions are severe (and therefore batteries are often being replaced), etc. In all cases, we work with you to see how we can best meet your specific requirements.
3. What's the difference between a typical flywheel and a Beacon flywheel?
The principle is the same, but little else. Beacon flywheels are made of carbon and fiberglass composites to withstand the very high speed of rotation. They do much more than simply provide "power smoothing"; Beacon flywheels store a lot of energy. To accomplish this they spin at up to 22,500 revolutions per minute. To better maintain this high-speed rotation, a vacuum system is used to reduce wind resistance and friction. Also, a high-speed magnetic lift system is employed to virtually eliminate friction and allow for long, maintenance-free operation. Beacon flywheels also have sophisticated electronics to control and convert the power from the flywheel to the voltage and current required by customers.
4. How does a flywheel store energy?
Energy is stored in kinetic, rather than chemical form, as is the case in battery systems. The formula for energy storage in a flywheel is: E = kMv[2] where E = energy; k is a constant based on the shape of the flywheel; M = mass of the flywheel and v is the rotational velocity of the flywheel (speed of rotation). Therefore, if the mass of the flywheel is doubled, the amount of energy is doubled. If you double the speed of rotation, you quadruple the amount of energy. This is why Beacon Power has selected a composite flywheel rim to allow high-speed rotation and higher energy storage in a smaller, lighter package.
5. What makes up a flywheel energy storage system?
The basic components are the flywheel energy storage unit (ESU) and the flywheel electronics module (FEM). The ESU contains the flywheel, motor/generator, hybrid magnetic/mechanical bearing system, vacuum system and vacuum housing. The FEM controls the flywheel, provides local and/or remote monitoring and converts the AC power coming in to drive the flywheel as well as converting the power from the flywheel to the desired customer output. Signal and motor cables link these two major components.
6. How is energy supplied from a flywheel?
The flywheel unit has an integrated motor/generator. Power is supplied from the flywheel electronics module to drive the flywheel via the motor. When utility power is lost, the motor instantly acts as a generator and variable frequency, variable voltage power is supplied from the flywheel unit to the flywheel electronics module where it's converted to power compatible with the customer's load.
7. Are flywheels safe?
Based on extensive analysis, careful design and thorough testing, the flywheel energy storage system units have been UL listed for electrical and mechanical safety. More recently, the Smart Energy flywheel system passed with flying colors the Telcordia Level 4 earthquake test - the equivalent of a 7.6-Richter scale disturbance for 40 seconds - without failure. These industry standard ratings are results of the extensive work Beacon Power has invested in verifying safety through real world testing. In addition to several redundant software and hardware systems to prevent over-speeds, Beacon Power has conducted testing to ensure that, in the event of failure, our flywheels shut down benignly. Since flywheels do store a tremendous amount of energy, which should not be released quickly, the composite rim is designed to contain rotor components. The system engineering has proven to release energy slowly, thus preventing any potential risk.
8. How are flywheels installed?
It depends on the model. The Smart Power ESU is typically installed above ground on a concrete/steel mounting plate. Smart Energy series ESUs are typically installed underground on a prefabricated concrete pad, and the FEM is installed above ground, generally on an existing or prefabricated pad. Alternative installation plans and configurations are possible, depending on customer requirements. |
