Department of Energy

'Recycling' Grid Energy with Flywheel Technology

September 30, 2010

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Seven-foot tall cylinders equipped with flywheel technology (shown above) will make up Beacon Power’s energy storage plant in Stephentown, N.Y. The company received a $43 million loan guarantee from the Energy Department to build the plant. | Photo courtesy of Beacon Power Corporation

Seven-foot tall cylinders equipped with flywheel technology (shown above) will make up Beacon Power’s energy storage plant in Stephentown, N.Y. The company received a $43 million loan guarantee from the Energy Department to build the plant. | Photo courtesy of Beacon Power Corporation


 

The electrical grid has been around much longer than other vital technologies, like telecommunications and the Internet.

Yet these systems have become more efficient in significantly shorter amounts of time, while grid technology has sat somewhat stagnant, causing outages, wasted energy and increased power plant emissions.

But the Obama Administration’s $3.4 billion investment in “smart grid” technology is changing that.

A good example comes from Beacon Power Corporation, a recipient of a Recovery Act loan guarantee.

The Tyngsboro, Mass.-based company’s innovative flywheel energy storage plant—which is the first of its kind in the world—is expected to improve electrical grid reliability and efficiency by continuously absorbing and injecting electricity, in effect “recycling” it.

The storage plant Beacon is building in Stephentown, N.Y., with the help of a $43 million loan guarantee from the Energy Department, will absorb electricity from New York’s grid when demand drops by accelerating the rotor to very high speeds to maintain the energy.


Changing the grid

When demand increases, the storage planet will inject energy by reducing speed of the flywheel, performing an essential grid service known as frequency regulation.

“It is certainly going to change the way the grid works,” says Gene Hunt, a Beacon Power spokesman. “No one denies that having the ability to store energy, as well as manage it better, makes sense.”

The 20 MW plant consists of 200 flywheel cylinders, which are now being placed at the outdoor site along the border of New York and Massachusetts.

The storage plant—which will supply 10 percent of the state’s average daily frequency regulation—is expected to have a 4 MW capacity online by the end of this year, with 20 MW by spring of next year.

About 250 direct and indirect jobs have been created across 10 states because of the project, according to Beacon Power.


Electrical economics

Regulations require grid operators to maintain a certain frequency in power delivery, so that electricity steadily flows to consumers. 

However, since electrical supply and demand are constantly fluctuating, grid operators have to signal to certain generators to increase or decrease their output to maintain that frequency.

But this approach has limitations.

Generators operate most efficiently at a constant output.  Thus, changes – fluctuations—in power delivery cause more fuel to be consumed, require more maintenance and result in higher plant C02 emissions. And delivery also takes longer.

“When the operator sends a message to ramp up or ramp down, fossil fuel power plants have up to five minutes to respond,” Hunt says. “When we get a signal from the grid operator to absorb energy or inject it into the grid to keep the frequency stable, we do it in less than four seconds.”

In short, if the energy was being stored—and made instantly available to smooth out these fluctuations in power supply—conventional generators would not have to work so hard and waste energy to keep up.

That’s where the flywheel storage comes in.

Green cylinders

Encased in seven-foot cylinders, these spinning flywheels are ideal for supporting renewable energy sources.

Wind and solar power are considered variable, since the sun is not always shining and wind speeds are not always at maximum. 

The variable energy produced by these sources affects grid stability, hence the need for energy storage “shock absorbers,” which can store the excess power or inject some if demand rises.

“The more wind and solar you put on the grid, the greater the need for stability,” Hunt says.  “And that’s where we come in.”

The flywheel storage plant in itself is energy efficient.

Beacon estimates that its 20 MW plant will reduce carbon dioxide emission up to 82 percent over its 20-year life compared to a coal, gas or pumped hydro plant that performs regulation.

“The ability to provide a service that would keep the grid stable, reduce fossil fuel consumption and do it in a cleaner, faster, cheaper way has the potential to change America,” Hunt says.