[1] HOW DOES SOLAR POWER WORK?
[2] The sun – that power plant ∈ the sky – bathes Earth ∈
[3] ample energy to fulfill all the world’s power needs many
[4] times over. It doesn’t give off carbon dioxide emissions.
[5] It won’t run out. And it’s free.
[6] So how on Earth can people turn this bounty of
[7] sunbeams into useful electricity?
[8] The sun’s light (and all light) contains energy. Usually,
[9] when light hits an object the energy turns into heat,
[10] like the warmth you feel while sitting ∈ the sun. But
[11] when light hits certain materials the energy turns into
[12] an electrical current instead, which we can then harness
[13] for power.
[14] Old-school solar technology uses large crystals made
[15] out of silicon, which produces an electrical current
[16] when struck by light. Silicon can do this because the electrons ∈ the crystal get up and move when exposed to light
[17] instead of just jiggling ∈ place to make heat. The silicon turns a good portion of light energy into electricity, but it is
[18] expensive because big crystals are hard to grow.
[20] Newer materials use smaller, cheaper crystals, such as copper-indium-gallium-selenide, that can be shaped into
[21] flexible films. This “thin-film” solar technology, however, is not as good as silicon at turning light into electricity.
[22] Right now, solar energy only accounts for a tiny portion of the U.S.’s total electricity generation, because it is more
[23] expensive than alternatives like cheap but highly polluting coal. Solar power is about five times as expensive as what
[24] people pay for the current that comes out of the outlets.
[25] In order to have a hope of replacing fossil fuels, scientists need to develop materials that can be easily mass-
[26] produced and convert enough sunlight to electricity to be worth the investment.
[27] By Susannah Locke - Scientific American - October 20, 2008
Na expressão “thin-film” solar technology (linha 21), o oposto de “thin” seria
