首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Natural gas Vehicles Kermit the Frog once said, "It’s not that easy bein’ green." Although he wasn’t referring to cars, his
Natural gas Vehicles Kermit the Frog once said, "It’s not that easy bein’ green." Although he wasn’t referring to cars, his
admin
2013-06-02
43
问题
Natural gas Vehicles
Kermit the Frog once said, "It’s not that easy bein’ green." Although he wasn’t referring to cars, his observation seems particularly appropriate for the auto industry today: Designing, developing and marketing "green" ears has not been an easy task, which is why gasoline powered vehicles still rule the road and fossil fuels still account for almost 75 percent of the world’s energy consumption. As gasoline prices soar and concern over harmful emission mounts, however, cars that run on alternate fuel sources will become increasingly important. A natural-gas vehicle, or NGV, is the perfect example of such a car--it’s fuel-efficient, environmentally friendly and offers a relatively low cost of ownership.
Natural Gas Basics
The word "gas" is a confusing term because it is used to describe many different substances that are similar but not exactly the same. For example, the "gas" you put in your car is gasoline, one component of crude oil, or petroleum. Petroleum is a dark, sticky liquid mixture of compounds formed underground by the decay of ancient marine animals.
Natural gas also comes from the decay of ancient organisms, but it naturally takes a gaseous form instead of a liquid form. Natural gas commonly occurs in association with crude oil. It is derived from both land plants and aquatic (水生的) organic matter and forms above or below oil deposits. It is often dissolved in crude oil at the high pressures existing in a reservoir. There are also reservoirs of natural gas, known as non-associated gas, that contain only gas and no oil.
Natural gas consists primarily of methane (沼气) and other hydrocarbon gases. Hydrocarbons are organic compounds composed only of the elements carbon and hydrogen. The hydrocarbons in natural gas are called saturated hydrocarbons because they contain hydrogen and carbon bound together by single bonds.
Like gasoline, natural gas is combustible (易燃的), which means it can be used in a combustion engine like gasoline. But cars that could burn natural gas didn’t appear on the scene until the 1930s.
From Field to Ford
We extract natural gas trapped in underground reservoirs by drilling wells into the earth. A modern well, equipped with diamond-studded drill bits, can drill to depths approaching 25,000 feet.
Throughout the 19th century, the use of natural gas remained localized because there was no way to transport large quantities of gas over long distances. In 1890, the invention of a leak proof pipeline coupling made it possible to transport gas miles from the source. Improvements in pipeline technology continued over the next two decades until long-distance gas transmission became practical. From 1927 to 1931, laborers constructed more than 10 major natural gas transmission systems in the United States, making natural gas a viable energy source for many applications. The oil shortages of the late 1960s and early 1970s brought renewed interest in natural gas as a fuel source, especially for automobiles.
Today, owners of natural-gas vehicles can fill up their cars at one of 1, 300 fueling stations located in the United States. Honda also offers a personal natural gas pump to people who purchase its natural-gas-powered Civic. The pump uses a home’s existing natural gas lines and can be installed for $500 to $1500.
Natural-gas Vehicle Design
Natural-gas vehicles use the same basic principles as gasoline-powered vehicles. In other words, the fuel (natural gas in this case) is mixed with air in the cylinder of a four-stroke engine and then ignited by a spark plug to move a piston (活塞) up and down. Although there are some differences between natural gas and gasoline in terms of flammability and ignition temperatures. NGVs themselves operate on the same fundamental concepts as gasoline-powered vehicles. Still, some modifications are required to make an NGV work efficiently. These changes are primarily in the fuel storage tank, the engine and the chassis (底盘).
Advantages
The biggest advantage of NGVs is that they reduce environmentally harmful emissions. Natural-gas vehicles can achieve up to a 93 percent reduction in carbon monoxide emissions, 33 percent reduction in emissions of various oxides of nitrogen and a 50 percent reduction in reactive hydrocarbons when compared to gasoline vehicles. NGVs also rate higher in particulate matter 10 (PM10) emissions. PM10 particles transport and deposit toxic materials through the air. NGVs that operate in diesel applications can reduce PM10 emissions by a factor of 10.
Natural-gas vehicles also offer these benefits:
NGVs are safer. The fuel storage tanks on an NGV are thicker and stronger than gasoline or diesel tanks. There has not been an NGV fuel-tank rupture in more than two years in the United States.
Natural gas costs are lower than gasoline. On average, natural gas costs one-third less than gasoline at the pump.
Natural gas is convenient and abundant. A well-established pipeline infrastructure exists in the United States to deliver natural gas to almost every urban area and most suburban areas. There are more than 1,300 NGV fueling stations in the United States, and more are being added every day.
Natural gas prices have exhibited significant stability compared to oil prices. Historically, natural gas prices have exhibited significant price stability compared to the prices of petroleum-based fuels. This stability makes it easier to plan accurately for long-term costs.
NGVs have lower maintenance costs. Because natural gas burns so cleanly, it results in less wear and tear on the engine and extends the time between tune-ups and oil changes.
Disadvantages
One of the biggest complaints about NGVs is that they aren’t as roomy as gasoline cars. This is because NGVs have to give up precious cargo and trunk space to accommodate the fuel storage cylinders. Not only that, these cylinders can be expensive to design and build--a contributing factor to. the higher overall costs of a Natural-gas vehicle compared to a gasoline-powered car.
Another drawback is the limited driving range of NGVs, which is typically about half that of a gasoline-powered vehicle. For example, Honda’s natural gas Civic, the Civic GX, can go up to 220 miles without refueling. A typical gasoline-powered Civic can go approximately 350.miles without refueling. If a dedicated NGV ran out of fuel on the road, it would have to he towed to the owner’s home or to a local natural gas refueling station, which might be harder to find than a "regular" gas station.
Finally, it should be noted that natural gas, like gasoline, is a fossil fuel and cannot be considered a renewable resource. While natural gas reserves in the United States are still considerable, they are not inexhaustible. Some predict that there are enough natural gas reserves remaining to last another 67.1 years, assuming that the 9,003 level of production continues.
The basic principles applied to natural-gas vehicles are quite different from those applied to gasoline-powered vehicles.
选项
A、Y
B、N
C、NG
答案
B
解析
本题涉及天然气交通工具的工作原理。小标题Natural Gas Vehicle Design下首段第一句指出天然气交通工具和汽油交通工具使用the same basic principles,题干中的quite different与此相悖。
转载请注明原文地址:https://kaotiyun.com/show/Cj67777K
0
大学英语六级
相关试题推荐
A、Heshouldbringhiscousintothepicnic.B、Thepicnicisgoingtobeverycrowded.C、She’ssorrythemancan’tcome’tothep
A、TherootofJim’shealthproblems.B、Thewoman’sproblemswithherworkaholicprofessor.C、Jim’srelationshipwithhisprofess
AlthoughBeethovencouldsitdownandcomposeeasily,hisreallygreatcompositionsdidnotcomeeasilyatall.Theycosthima
A、Writingbooksthatkeeptheminterested.B、Theendingofsomestories.C、Thefairytalesthewomanhasjustcovered.D、Thesci
Thepurposeofwritingthearticleisto______.Manyswimmingpoolsofferlessonsto______.
Thepurposeofwritingthearticleisto______.Peopledislikerunningbecausethey______.
Self-helpTraveling1.越来越多大学生选择“自助游”,原因是…2.也会带来一些问题3.你的看法
A、TeacherslikeProfessorJohnsonarerare.B、ProfessorJohnsonhaswonamilliondollars.C、Therearemanyteachersasgoodas
Allourdreamshavesomethingtodowithourfeelings,fears,longings,wishes,needsandmemories.Ifapersonishungry,orti
随机试题
2014年3月4日,A股上市公司“ST超日”(股票)(股票代码:002506)公告称“11超日债”本期利息将无法于原定付息日(即2014年3月7日)按期全额支付,付息比例仅为4.5%,并正式宣告违约,成为国内首例违约债券。这种风险属于债券的(
如何检修线束?
前列腺肿瘤患者
血清氯化物正常参考值是
下列有关国家赔偿的说法哪一项是正确的:()
2014年8月1日,某企业开始研究开发一项新技术,当月共发生研发支出200万元,其中,费用化的金额60万元,符合资本化条件的金额140万元。8月末,研发活动尚未完成。该企业2014年8月应计入当期利润总额的研发支出为()万元。
导游语言的运用四原则是()。
由实验者选择用来引起被试心理或行为变化的刺激变量叫()。
根据下列统计资料回答问题。抽样调查数据显示,2014年1—5月A区农村居民人均现金收入9053元,同比增长10.3%,增速较去年同期提高0.4个百分点;其中人均工资性收人为5421元,同比增长8.5%;人均家庭经营收入为760元,同比下降0.6%
DadCan’tHandleTheseToysAnyparentwithachild【C1】______theagesof3and11cantellyou【C2】______technologyhascrept
最新回复
(
0
)