1.2　Sustainable Transportation

Text（课文）

The current model of the personal transportation system is not sustainable in the long run because the Earth has limited reserves of fossil fuel，which provide 97% of all transportation energy needs at the present time.To understand how sustainable transportation can be achieved，let us look at the ways energy can be derived and the ways vehicles are powered.

The energy available to us can be divided into three categories:renewable energy，fossil fuelbased non-renewable energy and nuclear energy.Renewable energy includes hydropower，solar，wind，ocean，geothermal，biomass and so on.Non-renewable energy includes coal，oil，and natural gas.Nuclear energy，though abundant，is not renewable since there are limited resources of uranium and other radioactive elements on Earth.In addition，there is concern on nuclear safety（such as the recent accident in Japan due to earthquake and tsunami）and nuclear waste processing in the long term.Biomass energy is renewable because it can be derived from wood，crops，cellulose，garbage，and landfill.Electricity and hydrogen are secondary forms of energy.They can be generated by using a variety of sources of original energy，including renewable and non-renewable energy.Gasoline，diesel，and syngas are energy carriers derived from fossil fuel.

Figure 1.4 shows the different types of sources of energy，energy carriers and vehicles.Conventional gasoline/diesel-powered vehicles rely on liquid fuel which can only be derived from fossil fuel.HEVs，though more efficient and consuming less fuel than conventional vehicles，still rely on fossil fuel as the primary energy.Therefore，both conventional cars and HEVs are not sustainable.EVs and fuel cell vehicles rely on electricity and hydrogen，respectively.Both electricity and hydrogen can be generated from renewable energy sources，therefore they are sustainable as long as only renewable energy sources are used for the purpose.PHEVs，though not totally sustainable，offer the advantages of both conventional vehicles and EVs at the same time.PHEVs can displace fossil fuel usages by using grid electricity.They are not the ultimate solution for sustainability but they build a pathway to future sustainability.

Figure 1.4　A sustainable transportation model

New words and expressions（单词和短语）

1.New words（单词）

2. Expressions（短语）

Notes to the text（难点解析）

★1.The energy available to us can be divided into three categories:renewable energy，fossil fuel-based non-renewable energy and nuclear energy.Renewable energy includes hydropower，solar，wind，ocean，geothermal，biomass and so on.Non-renewable energy includes coal，oil and natural gas.Nuclear energy，though abundant，is not renewable since there are limited resources of uranium and other radioactive elements on Earth.我们能够获取的能源形式可分为三类:可再生能源、基于化石燃料的不可再生能源以及核能。可再生能源包括水力、太阳能、风能、海洋能、地热能、生物能等。不可再生能源包括煤、石油和天然气。核能虽然很丰富，但也是不可再生的，这是因为地球上的铀和其他放射性元素是有限的。

★2.PHEVs，though not totally sustainable，offer the advantages of both conventional vehicles and EVs at the same time.PHEVs can displace fossil fuel usage by using grid electricity.PHEVs虽然不是可完全持续发展的，但是同时具备了传统汽车和纯电动汽车的优点。PHEVs能够通过使用电网的电能来代替化石燃料的使用。

Exercises（练习）

◆1.Translate the following passages（expressions）into Chinese（英译汉）

（1）Nuclear energy，though abundant，is not renewable.

（2）sustainable transportation

（3）natural gas

◆2.Translate the following passages（expressions）into English（汉译英）

（1）不可再生能源包括煤、石油和天然气。

（2）可再生能源

（3）太阳能

◆3.Fill in the blanks with the suitable words according to the text

Renewable energy includes______，______，______，______，______，______and so on.Non-renewable energy includes coal，oil and natural gas.Nuclear energy，though abundant，is______since there are limited resources of uranium and other radioactive elements on Earth.

◆4.Directions:Answer the following questions briefly according to the text

How many categories can the energy available to us be divided into？What are they？

Reading material（阅读材料）

Electrically-driven vehicles have many advantages and challenges.Electricity is more efficient than the combustion process in a car.Well-to-wheel studies show that，even if the electricity is generated from petroleum，the equivalent miles that can be driven by 1 gallon（3.8 L）of gasoline is 108 miles（173 km）in an electric car，compared to 33 miles（53 km）in an internal combustion engine（ICE）car.In a simpler comparison，it costs 2 cents per mile to use electricity（at US＄0.12 per kW·h）but 10 cents per mile to use gasoline（at＄3.30 per gallon）for a compact car.

Electricity can be generated through renewable sources，such as hydroelectric，wind，solar and biomass.On the other hand，the current electricity grid has extra capacity available at night when the usage of electricity is off-peak.It is ideal to charge electric vehicles（EVs）at night when the grid has extra energy capacity available.