Now, it seems, the time has come to reinvent the flywheel.
Today’s engineers are repurposing Watt’s device into a promising alternative to batteries and other high-tech means of storing energy. Among their aims: using flywheels to make renewable energy more useful, and turning trains and buses into hybrid vehicles.
In its simplest form, a flywheel is a wheel, disk or cylinder that spins around a stationary axis. It works on the same principle as the potter’s wheel, which has been used to mold clay vessels since the dawn of civilization.
A flywheel’s momentum, which depends on how heavy the wheel is and how fast it’s spinning, can contain an impressive amount of energy. And if something acts as a brake on the wheel, this energy can be released — in the form of electricity, for example — with impressive suddenness.
Finding new, improved ways to store energy is crucial partly because of the growth of renewable energy sources such as wind and solar power. The former is available only when the wind is blowing. The latter, only when the sun shines. Unless some of that energy can be stored for later use, renewables will never be able to power the world’s needs around the clock.
Better energy storage methods could also improve fuel efficiency and curtail costs at conventional power plants, reduce their carbon emissions and prevent blackouts.
Even though conventional plants can often increase or decrease energy production as needed — by throwing more coal in the furnace, for example — they can’t adjust their output instantaneously.
Energy demand, however, often comes in sudden surges. A large factory powers up its equipment all at once. A rush of commuters arriving home almost simultaneously turn on all their air conditioners and TVs. A baseball stadium’s lights blink on. These and other daily occurrences cause sharp and not entirely predictable spikes in demand for electricity.
Consequently, power plants routinely generate more electricity at a given moment than their customers are expected to consume. The excess goes to waste. But that’s more acceptable than being overwhelmed by an unexpected spike in demand, which can rapidly lead to a blackout.
If a standby supply of stored energy is available for rapid deployment, plant operators can use it as a buffer against demand surges. They could then get away with less overproduction, minimizing waste and emissions. Starting in 2009, financial incentives from the federal government and some states have encouraged companies to seek ways to store energy and release it to the grid quickly when demand spikes.
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