Задание №16315 ЕГЭ по Английскому языку

Flywheel Batteries as a New Spin on Energy Storage

A friend of mine recently installed solar panels on his roof to generate electricity. They were quite expensive, but my friend considers it an investment that will pay for itself in lower electricity bills over a period of decades. Of course, the panels generate electricity only when the sun is shining. The house is still connected to the electrical grid just like every other house in the neighborhood, but in such a way that it uses electricity from the grid only when the demand is greater than the output from the solar panels. When the panels are producing more electricity than is being used, the electric meter spins backward, and the electric company effectively buys the excess power. So if there were a power outage, the house would have electricity only during the day.

Homes that are “off the grid” and use solar panels or windmills to produce electricity must store the excess for times when insufficient power is being produced. The usual way to do this is to install a large bank of lead-acid batteries, similar to the ones used in cars. When electricity is being generated, it’s stored in the batteries, and when it’s needed, it’s drained from the batteries.

But there’s a problem with using batteries for storing electricity: they wear out. Even the most sophisticated modern batteries used in cell phones and laptops can only be discharged and recharged a finite number of times; sooner or later, they refuse to hold a charge. Depending on the type of battery and how it’s used, the lifespan can be as little as three to five years. Now, buying a new laptop battery every few years for $50 is one thing, but buying enough batteries to power a whole house is going to be enormously expensive. Meanwhile, those old batteries will need to be disposed of very carefully, because they contain toxic elements. And let’s not forget that such high-capacity batteries are both heavy and bulky.

Although chemical batteries are likely to be around for a very long time, those with a need for high-capacity, long-term electricity storage are eagerly looking for alternatives. One such alternative is based on a very old and simple device: the flywheel. A flywheel is simply a heavy spinning wheel that stores kinetic energy and then releases it as needed. Flywheels are common in mechanical devices from potters’ wheels to automobiles to clocks as a means of regulating or smoothing motion that comes in spurts. Because a flywheel can build up a good bit of inertia, it can keep a mechanism moving during lulls in energy input.

Now people are turning flywheels into batteries. Conceptually, a flywheel battery is very simple. Hook up a motor to a flywheel to spin it when electricity is supplied (storing the energy as kinetic energy). When you want to retrieve energy from the flywheel, hook it up to a generator. (In fact, the motor and the generator can be one and the same.) So you put electricity in and get electricity out, and in the meantime it’s “stored” as the motion of a spinning wheel.

Two problems that have not yet been solved are cost and scalability. Although it’s possible to purchase a flywheel battery to act as a backup power supply for your home or business, it will set you back many thousands of dollars — enough to pay for quite a few years’ worth of batteries. In an era that values devices with no moving parts as a design triumph, it’s fascinating to watch a good old-fashioned spinning wheel emerge as the battery of the future.