Solar rock: the music world heats up as musicians plug into the sun.
The album's producers-Hollywood Records and the environmental group Greenpeace--trucked Cyrus across the U.S. to power and record concerts, and mix all the songs on the CD. The gol was to demonstrate that "nonpolluting, efficient solar energy is not some 25th-century pipe dream," says Kate Karam, president of Greenpeace Records.
Right now, she points out, "four fifths of the world's electricity is provided by coal, oil and gas [fossil fuels], and by nuclear power [see graph, p. 16]. All cause serious environmental problems. We wanted to show that there are practical alternatives for generating electricity."
Karam strums up solar energy's main advantages: no pollution, and no end in sight to the power source--the sun, which astronomers expect to shine for another 5 billion years. The U.S. alone receives more energy in the form of sunlight in less than three hours, than from all the fossil fuels we burn every year.
Cyrus plugs into a small share of that power via 40 panels of solar cells on its roof. These waferlike layers of the element silicon soak up the solar rays and convert them to electrical power. Here's how:
Small bundles of pure sunlight, called photons, penetrate the solar cells and knock electrons off some of the silicon atoms. Other silicon atoms in the next layer give up electrons to fill the vacated "holes" (see diagram, above).
"Eventually, you get a stream of electrons moving in one direction [an electric current]," says Dave Wallerstein of Siemens Solar Industries, the company that made Cyrus's solar panels. The current gets stored in Cyrus's two batteries, inside the van.
When the batteries are all charged up, Cyrus can power a recording studio for 15 hours. That's all the electricity your home might need for several days!
There are a few slight hitches, though. For one thing, Cyrus's solar panels, like all solar cells, produce only direct current (DC) electricity--a single, steady voltage (level of electrical force) flowing in one direction, says Paul Basore, a solar-energy specialist at Sandia National Laboratories in New Mexico.
That's a problem because different electrical devices--e.g., microphones and amplifiers--require different voltages. Each device has a built-in transformer, that changes the incoming voltage to the power that's needed. But transformers can only be used with alternating current (AC), the kind of power you get from a wall socket (where the flow of electrons reverses direction many times a second). With AC power, an amplifier (which requires lots of power) can "step up" the voltage to rock the house, while a microphone (which needs much less energy) can step it down so it won't blow out.
To provide this kind of variable voltage from the sun, Cyrus's engineers built in two inverters, electrical devices that convert DC power to AC. With Cyrus pumping out AC current, the bands were ready to play some solar rock.
How did the recording go? For the most part, just fine, says Greenpeace's Karam. There was only one "seare."
"Cyrus almost ran out of its stored power halfway through U2's show in San Diego," she recalls. Like regular batteries, Cyrus's can only store a limited amount of energy. And because the band had had "a really long sound check and it took a long time to get everything up and running [before the show]," Karam says, the batteries were running low. Fortunately, it wasn't until 10 minutes after the concert that the power ran out.
Such limitations are one reason solar energy isn't used more widely today, says solar-energy expert Basore. Another drawback: To capture a larger share of the solar energy that shines on us every day, we'd need lots of solar cells, Basore says. And right now, solar cells are expensive to manufacture.
Solar-energy engineers are making progress, says David Meakin of the Solar Energy Research and Education Foundation. As little as five years ago, solar electricity cost more than 50 cents a kilowatt-hour (a measure of the energy needed to run a 1,000-watt appliance--say, a blowdryer--for one hour). Today, thanks to advances in solar-cell manufacturing and cheaper DC to AC inverters, the cost has come down--to about 30 cents per kilowatt-hour.
But generating electricity by burning fossil fuels still costs less-about 8 cents per kilowatt-hour. So solar-energy programs--including projects like Cyrus--still have a ways to go.
Solar supporters, like those who sponsored Cyrus's recording of Alternative NRG, won't give up easily, though. Since its trans-American rock tour, Cyrus has powered more than 80 events in 17 states, including the multimedia exhibits at the 1994 Woodstock music festival. And the musicians remain committed to the "alternative energy" cause. As the band R.E.M. told a music publication: "We hope this album will help turn the tide in favor of nonpolluting energy sources."
Meanwhile, maybe you can find ways to take advantage of the sun's awesome power--even if you don't have solar cells. Start by trying t hands-on activity at right.
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|Title Annotation:||using solar panels for energy|
|Date:||May 5, 1995|
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