Maintaining the electrical grid’s frequency to 50 Hz in Europe and 60 Hz in the U.S. is sometimes a difficult task to do for the power plants. When a large number of grid users coincidentally charge their electric cars at once, for example, because of the charge put on the grid network, the frequency drops, less power is transferred, and the drop could even cause troubles to some unprotected electricity consumers.
The reverse effect happens when there are suddenly very few consumers: the grid frequency starts climbing, and that’s not good, either.
To compensate for the grid fluctuations, the power plants automatically turn on and shut off generators, be them coal or gas-fired. Everything has to happen very fast, and that causes long-term damages to the power plants. Supercapacitors are a possible source of energy in case a buffer is need, but to provide the entire city of New York, for example, with a supercapacitors tank that can withstand its energy fluctuations is very expensive, both because of the equipment’s cost, and their maintenance.
Massachusetts-based Beacon Power has been contracted to deliver an energy buffer solution for those frequency fluctuations we were talking about earlier. Their solution consists of an array of 200 flywheels, each weighing 2000 pounds (approx. 1 ton). The flywheels are made of fiberglass, resins and carbon fiber, floating on magnetic bearings and encased in a voided capsule, so there’s no air friction. As you may already know, flywheels are good for energy storage and for instantaneous powerful discharge, so you’ll have the energy right when you need it.
Beacon Power’s flywheels will spin at up to 16,000 rpm, and will be powered by the excess energy produced at night or at times when power consumption is not so big. The numbers are also impressive: the entire array will be able to store about 10% (20 MW) of New York’s energy needs.
Beacon power has been awarded $43 million to build the flywheel plant that will regulate New York’s power grid. The entire project costs $69 million and is expected to last at least 20 years. Future plants will cost much less than that, only about a half – they will be in New England and in a still secret East Coast location. The NY plant will be ready in 2011.