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
Naturalgas Vehicles Kermit the Frog once said, "It’s not that easy being green." Although he wasn’t referring to cars, his o
Naturalgas Vehicles Kermit the Frog once said, "It’s not that easy being green." Although he wasn’t referring to cars, his o
admin
2012-10-30
62
问题
Naturalgas Vehicles
Kermit the Frog once said, "It’s not that easy being green." Although he wasn’t referring to cars, his observation seems particularly appropriate for the auto industry today: Designing, developing and marketing "green" cars has not been an easy task, which is why gasolinepowered vehicles still rule the road and fossil fuels still ac count for almost 75 percent of the world’s energy consumption. As gasoline prices soar and concern over harmful emission mounts, how ever, cars that run on alternate fuel sources will become increasingly important. A naturalgas vehicle, or NGV, is the perfect example of such a carit’s fuelefficient, 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 de scribe many different substances that are similar hut 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 tile decay of ancient marine animals.
Natural gas also cranes 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(水中的) 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 nonassociated gas, that contain only gas and no oil.
Natural gas consists primarily of methane(甲烷) 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, 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 modem well, equipped with diamondstudded 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 leakproof pipeline coupling made it possible to transport gas miles from the source, Improvements in pipeline technology continued over the next two decades 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 naturalgas vehicles can fill up their cars at one of 1,300 fueling stations located in the United States. Honda al so offers a personal natural gas pump to people who purchase its naturalgaspowered Civic. The pump uses a home’s existing natural gas lines and can be installed for $500 to $1500.
Naturalgas Vehicle Design
Naturalgas 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 fourstroke engine and then ignited by a spark plug to move a piston 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 gasolinepowered 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.
Advantages
The biggest advantage of NGVs is that they reduce environ mentally harmful emissions. Naturalgas 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 e missions by a factor of 10.
Naturalgas vehicles also offer these benefits:
NGVs are safer. The fuel storage tanks on an NGV are thicker and stronger than gasoline or diesel (内燃机车) tanks. There has not been an NGV fueltank rupture in more than two years in the United States.
Natural gas costs are lower than gasoline. On average, natural gas costs onethird less than gasoline at the pump.
Natural gas is convenient and abundant. A weltestablished 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 petroleumbased fuels. This stability makes it easier to plan accurately for longterm 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 tuneups 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 builda contributing factor to the higher overall costs of a naturalgas vehicle compared to a gasolinepowered car.
Another drawback is the limited driving range of NGVs, which is typically about half that of a gasolinepowered vehicle. For example, Honda’s natural gas Civic, the Civic GX, can go up to 220 miles without refueling. A typical gasolinepowered Civic can go approximately 350 miles without refueling. If a dedicated NGV ran out of fuel on the road, it would have to be 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 re serves remaining to last another 67.1 years, assuming that the 2003 level of production continues.
Not until the ______ were the cars that could burn natural gas invented.
选项
答案
1930s
解析
从第一个小标题下最后一段可找到答案。
转载请注明原文地址:https://kaotiyun.com/show/rp57777K
0
大学英语四级
相关试题推荐
It’sofficialthatmarriedpeoplearehealthier,oratleasttheythinktheyare.AnAmerican【B1】______ofover100,000peoples
LienChan’ssuccessfulvisittotheMainlandofChinaencouragedmoreandmoreChinesepeople_____________(为祖国的未来作贡献).
A、Somestudentsatthebackcannotheartheprofessor.B、Theprofessorhaschangedhisreadingassignment.C、Someofthestudent
ForAmericans,timeismoney.Theysay,"Youonlygetsomuchtimeinthislife;you’dbetteruseitwisely."The【B1】______will
Itisn’tworth______Bob,whoisalwaysunpunctual.
Althougharchitecturehasartisticqualities,itmustalsosatisfyanumberofimportantpractical
Therearequitesomepeople______(会什么事都以你为榜样)。
Althoughtheenjoymentofcolorisuniversalandcolortheoryhasallkindsofnamestoit,colorremainsaveryemotionalands
A、Privateschoolswereexpensive.B、Teacherswerenotgoodenough.C、Womencouldn’tlearnFrench.D、Womendidn’tlikeschooling.
A、Comfortable,attractiverooms.B、Uglyrooms.C、White-coloredrooms.D、Dark-browncoloredrooms.A细节题。浏览选项可知,选项中是四个不同特点的房间,听音时注
随机试题
“艾宾浩斯遗忘曲线”说明遗忘规律是()。
小刚现年10岁,某日逛商场时看到某牌号纯平25寸彩电正举行优惠展销,想起父母曾提起过要买彩电的事。就赶回家告诉父母,但家中没人,父母都没联系上。但优惠的彩电数量有限,他便拿出自己的积蓄,以3900元的价格买了一台,因购彩电还附赠奖券,小刚随便就抽了一张,其
某宗地(丘)有5个界址点,其坐标分别为J1(5,1)、J2(6,1)、J3(4,4)、J4(2,2)、J5(3,1),则该宗地的面积数值为()。
回答下列选择题商业物业所处的位置不同,租金会有较大的差异。在同一层商场内,对其租金起最终决定作用的因素是()。
施工索赔最重要的依据是( )。
应计入当期损益的费用是()。
下列选项中,属于客户隐私的有()。
A公司主要从事电子产品的生产与销售,不考虑所得税等影响。A公司2014年至2015年发生的业务如下。(1)A公司为了进军日用化工产品的生产与销售行业,于2014年1月1日以银行存款5600万元从B公司股东处购买了B公司100%的股权。A公司与B公司的原股
历史学家吕西阿斯在赞扬雅典人的祖先时,他声称他们是当时第一个,也是唯一从他们的国家中赶走统治阶级,建立民主攻治的民族,他们相信全国人民的自由将成为最强有力的联系。材料中提到的这种“自由”是()
ReadingPassage2hassixsectionsA-F.ChoosethemostsuitableheadingsforsectionsA-DandFfromthelistofheadingsbelow
最新回复
(
0
)