Since the legendary Prometheus first stole the fire of heaven, virtually all energy consumed by human beings has been fathered by the Sun. Coal, oil, and gas are residues of plants and animals once fired to life by the warm rays of our nearest star. Solar heat also drives the Earth’s rain cycle, powering modern hydroelectric generators. Windmills that pump water or produce electricity turn because of solar-heated currents of air. But the Earth is fast running out of these precious reserves of stored sunshine. At our current pace, we will consume in the next 25 years alone an amount equal to all the energy used by human beings in recorded history. If such consumption continues, obviously alternative sources must be found. And the majority of experts agree that mankind must look to the Sun to help solve our energy needs. Already the Sun’s energy is being put to limited use in homes and buildings around the world. The most common examples are rooftop solar heaters that provide cheap hot water for washing and bathing. Today the Sun’s roaring hydrogen-fueled furnace powers educational-television sets in Africa and navigation lights on Gulf of Mexico oil rigs. And nearly every spacecraft that has ever rocketed skyward has depended on purple-blue panels of solar cells. Farfetched? Perhaps not, if we learn to switch on more of the sunshine that warms us all. 【題組】19 Hydroelectric power uses to generate electricity.
(A) water (B) wind (C) gas (D) sunshine
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