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Passage Three Scraps of food could soon be helping power your home, thanks to an ultra-cheap bacteria-driven battery. Its developers hope that instead of feeding the dog or making garden compost(混合肥料) ,organic household waste could top up your home’s electricity. Although such "microbial fuel cells" (MFCs)have been developed in the past, they have always proved extremely inefficient and expensive. Now Chris Melhuish and technologists at the University of the West of England(UWE)in Bristol have come up with a simplified MFC that costs as little as ￡10 to make. Right now, their fuel cell runs only on sugar cubes, since these produce almost no waste when broken down, but they aim to move on to carrot power. "It has to be able to use raw materials, rather than giving it a refined fuel," says Melhuish. Inside the Walkman-sized battery, a colony of E. coil bacteria produce enzymes that break down carbohydrates, releasing hydrogen atoms. The cell also contains chemicals that drive a series of redox, or reduction and oxidation reactions, stripping electrons from the hydrogen atoms and delivering them steadily to the fuel cell’s anode(正极). This creates a voltage that can be used to power a circuit. To prove the MFC works, the researchers are using it to power a small light-sensitive robot. And when a number of the cells are connected in series, they could power domestic appliances, running a 40-watt bulb for eight hours on about 50 grams of sugar. Earlier MFCs were inefficient because they relied on energy-hungry filters and pumps. By experimenting with different anode materials, the UWE team have figured out how to make their system work: they dump the bacteria and redox chemicals directly into the cell. In its current form, the UWE team says its organic battery can produce eight times as much power as any previous MFC. But Melhuish wants to improve this, both by scaling it up and finding a better mix of redox chemicals. Earlier MFCs were inefficient because they ______.
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Why did man have to track his target at a close range when using a short bow
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Passage Four Is there enough oil beneath the Arctic National Wildlife Refuge (ANWR)to help secure America’s energy future President Bush certainly thinks so. He has argued that tapping ANWR’s oil would help ease California’s electricity crisis and provide a major boost to the country’s energy independence. But no one knows for sure how much crude oil lies buried beneath the frozen earth, with the last government survey, conducted in 1998, projecting output anywhere from 3 billion to 16 billion barrels. The oil industry goes with the high end of the range, which could equal as much as 10% of U.S. consumption for as long as six years. By pumping more than 1 million barrels a day from the reserve for the next two to three decades, lobbyists claim, the nation could cut back on imports equivalent to all shipments to the U.S. from Saudi Arabia. Sounds good. An oil boom would also mean a multibillion-dollar windfall(意外之才) in tax revenues, royalties (开采权使用费)and leasing fees for Alaska and the Federal Government. Best of all, advocates of drilling say, damage to the environment would be insignificant. "We’ve never had a documented case of an oil rig chasing deer out onto the pack ice," says Alaska State Representative Scott Ogan. Not so fast, say environmentalists. Sticking to the low end of government estimates, the National Resources Defense Council says there may be no more than 3.2 billion barrels of economically recoverable oil in the coastal plain of ANWR, a drop in the bucket that would do virtually nothing to ease America’s energy problems. And consumers would wait up to a decade to gain any benefits, because drilling could begin only after much bargaining over leases, environmental permits and regulatory review. As for ANWR’s impact on the California power crisis, environmentalists point out that oil is responsible for only 1% of the Golden State’s electricity output—and just 3% of the nation’s. Which of the following is NOT TURE according to the passage
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