FarmersintheUnitedStatessometimesplantswitchgrassasabor...
问题详情:
Farmers in the United States sometimes plant switch grass as a border crop. But could this tall grass lower the nation’s dependence on foreign oil?
The Department of Energy plans to invest hundreds of millions of dollars to help produce fuels from materials that are not part of the food supply. Growing corn, or maize, for fuel has raised concerns about the supply and cost of corn available for food and animal feed.
Fuel made from switch grass or forestry waste like sawdust(锯屑) is known as cellulosic(有纤维质的) ethanol(酒精). Department officials say it contains more energy and produces fewer greenhouse gases than ethanol made from corn. Switch grass is also easier to grow.
Last month, the Proceedings of the National Academy of Sciences published a study of switch grass grown on low-quality land. Government scientist Ken Vogel was the lead author. The study says the switch grass produced five times more energy than was needed to grow it. Also, it says switch grass, over its lifetime from crop to fuel, produces much less carbon compared to gasoline.
Fossil fuels like oil take carbon from the ground and release it as waste gas when the fuel is burned. Biofuels(生物燃料) like corn and cellulosic ethanol also produce greenhouse gases, through growing crops and making the fuel. The difference is that biofuels remove carbon from the atmosphere through the growth of the feedstock, the material for the fuel.
Science magazine just published two studies of biofuels and the heat-trapping gases that scientists link to climate change. One of the reports notes that most studies have found that substituting biofuels for gasoline will reduce greenhouse gases.
But it says the earlier studies failed to count the carbon released into the atmosphere as farmers worldwide react to higher prices. They are clearing forests and grasslands to make way for new cropland to replace the grain used for biofuels. Doing so can release much of the carbon stored in the plants and soil, and sacrifice future storage.
The study found that corn-based ethanol could increase greenhouse gases for years from land use change. And it found that biofuels from switch grass, if grown on American corn land, could also increase emissions, though by less.
The study team, led by Timothy Searchinger at Princeton University, says the result shows the value of using waste products for fuel. The other report says carbon savings depend on how biofuels are produced.
1.Switch grass is a better fuel than corn in all the following aspects except .
A.switch grass grows on low – quality land
B.switch grass produces more energy than corn
C.switch grass produces fewer greenhouse gases than corn
D.switchgears is easier to grow
2.It is implied in the underlined sentence that .
A.an increasing number of people worry about the use of corn as fuel
B.there will be an increase in price of corn for food if it is used as fuel
C.there will be an decrease in quantity of corn for food if it is used as fuel
D.all the above choices are right
3.Biofuels produces much less carbon compared to Fossil fuels in that .
A.biofuels produce less greenhouse gases than fossil fuels
B.fossil fuels release carbon while biofuels not when burning
C.biofuels take in carbon from the air when they are growing
D.biofuels produce greenhouse gases only when they are burning
4.The passage indicates that .
A.we’d better make full use of biofuels to protect the environment
B.the value of using biofuels remains to be further studied
C.it’s costless to grow biofeuls
D.biofuels are just switchgrass and corn
【回答】
ADCB
知识点:阅读理解
题型:未分类
-
下列各组词语中,没有错别字的一组是A.闲情逸致 声名鹊起 意气相投 金碧辉煌B.情随事迁 隐约...
问题详情:下列各组词语中,没有错别字的一组是A.闲情逸致 声名鹊起 意气相投 金碧辉煌B.情随事迁 隐约其辞 夸夸奇谈 前赴后继C.梦寐以求 百折不挠 闻过饰非 惨淡经营D.言简意赅 言近指远 伸张正义 良辰...
-
以下各组国家中,人口增长模式不同的是A.阿曼和孟加拉国 B...
问题详情:以下各组国家中,人口增长模式不同的是A.阿曼和孟加拉国 B.巴西和匈牙利C.澳大利亚和美国 D.韩国和新加坡【回答】B知识点:人口与地理环境...
-
_______youeatthecorrectfoods_____beabletokeepfitandstay...
问题详情:_______youeatthecorrectfoods_____beabletokeepfitandstayhealthy.A.Unless;willyou B.Unless;youwillC.Onlyif;youwill D.Onlyif;willyou【回答】D知识点:倒装与省略题型:选择题...
-
阅读下面的文字,完成14―17题。凄与悲的距离白水河听《二泉映月》,在优美的乐曲中,你能感受到一种感伤,一种凄...
问题详情:阅读下面的文字,完成14―17题。凄与悲的距离白水河听《二泉映月》,在优美的乐曲中,你能感受到一种感伤,一种凄凉。它这样的美,美得让人陶醉,它这样的凄怨,凄怨得让人落泪。深入它,才知道它凝聚了一位贫苦艺术家一生的感慨、叹伤,它又凝聚了他一生的流浪。阿炳,这...
相关文章
- ---Thestudentslookverytiredafterthesportsmeeting.---We...
- 阅读理解Itseemstobestrangetomostofyouthatthereisablindspot(...
- It'sinterestingtoseehowpeoplemakeuseofthetimetheyspendo...
- NewYorkStatehaspassedtheUSA’sfirststatelawbanning(禁止)mo...
- Answerthequestions(根据短文内容回答下列问题)Christmasisanimportantf...
- 阅读与回答问题SixteenisaspecialageintheUnitedStates.There’soft...
- Astheymigrate(迁移),butterfliesandmoths(飞蛾)choosethewinds...
- 完形填空ThetelephoneringsandSueanswersit.“1 IspeaktoMrsPott...
- BeijingOperaisthequintessence(精髓)ofChina.It'sthemostwel...
- Mrs.Whitelikessports.Sheseemsshortandthin,butsheisstron...