Chapter 5 Energy Resources and Consumption 第五章 能源和消耗

1 Energy Concepts 能量的概念

1.1 Energy and Power 能量和功率

能量可以有各种形式，机械能、电能、化学能、核能、太阳能、热能等。能量的各种形式可以相互转换，但是总量不变。能量在物理中的符号一般是E，其国际单位是焦耳（J），量纲M×L2×T-2。除焦耳外，常用的还有千瓦·时（kWh）和卡（cal）：

1J = 0.238,8 cal =（3.6×106）-1kWh

Energy can take many forms, including mechanical, electrical, chemical, nuclear, solar,thermal, and heat. Physicists refer to energy as the ability to do work, giving the idea that all energy can somehow be used to move objects or perform mechanical labor. Accordingly, work and energy are measured by the same units. In the metric system, the unit of energy is the joule (J).

1.1.1 Heat 热能

Heat is a special form of energy that initially was not recognized as such. The history of heat has left us with different names for its units of measure, namely calories and Btus (British thermal units), but heat is just another form of energy.

●One Calorie 1卡路里

1卡路里指能使1升水升高1摄氏度所需的热量，相当于4.184焦耳的热能。

One calorie is the heat required to raise the temperature of one gram of water by one Celsius degree.

1 cal = 4.184 J

●One Btu 1 Btu

1 Btu is the heat required to raise the temperature of one pound of water by one Fahrenheit degree. It may be helpful to know that 1 Btu is approximately the amount of heat released by the burning of one large kitchen match.

1 Btu = 252 cal = 1,055 J

1.1.2 Power 功率

功率是指物体做功的快慢，在物理学里功率P =功（W）/时间（t），单位是瓦（W）。

Power is the rate at which energy is used, so it is related to but not the same quantity as energy. The international unit of power is the watt, which is equivalent to an energy flow rate of one joule per second.

如何利用功率计算功，相信大家的物理知识已经足够应付所有的计算，在这里我们就不详细讲述了。简单列出一个公式，帮大家唤醒物理知识。

Calculating energy from power: multiply power by the time of use.

●For example: 1 joule = 1 watt×1 sec. For electrical energy, the commonly accepted unit is the kilowatt-hour (kWh).

1 kWh = 1 kW×1 hr

●The First Law of Thermodynamics 热力学第一定律

热力学第一定律阐述了能量守恒和转换的定律，其具体内容为：自然界一切物体都具有能量，能量有各种不同形式，它能从一种形式转化为另一种形式，从一个物体传递给另一个物体，在转化和传递过程中能量的总和不变。

It also known as the law of the conservation of energy, establishes that energy cannot be created or destroyed, only converted from one form to another.

ΔU = Q+W

●The Second Law of Thermodynamics 热力学第二定律

热力学第二定律的主要内容为：不可能把热从低温物体传到高温物体而不产生其他影响；不可能从单一热源取热使之完全转换为有用的功而不产生其他影响；不可逆热力过程中熵的微增量总是大于零。

It states that in all energy conversions, some low-quality heat (waste heat) must always be produced.

●Converting units 换算单位

Converting one unit to another requires the correct use of conversion factors. Any conversion factors required on the AP Environmental Science exam will be provided. Common metric prefixes (micro-, milli-, centi-, kilo-, mega-, and giga-) are deemed common knowledge and typically are not provided on the AP Environmental Science exam.

2 Energy Consumption 能量的消耗

2.1 History 历史

2.1.1 The Industrial Revolution工业革命

工业革命起源于18世纪英格兰中部，是指资本主义生产完成了从手工业向机器大工业过渡的阶段。瓦特对蒸汽机的改良等一系列技术革命引发了手工劳动向动力机器生产的转变。

Beginning in England in the last part of the 18th century, it changed societies from agriculturally-based to an industrialized. During this time there were many technological advancements, including steam power. New fuels such as coal and petroleum, were used in the new steam engines. The growth of cities was one of the outcomes of the Industrial Revolution. From the time of its start the amount of carbon dioxide in the atmosphere has increased by about 40%.

2.1.2 Energy Crises 能源危机

1973: caused by an OPEC oil export embargo led to a dramatic increase in the price of gasoline, long lines at gas stations and rationing

1979: caused by the Iranian Revolution led to a dramatic increase in the price of gasoline, long lines at gas stations and rationing in some states

1990: caused by the first Gulf War led to a dramatic increase in the price of gasoline

2.2 Present Energy Use 当今能源利用

Over 80% of the energy consumed in the world is from nonrenewable sources including fossil fuels (76%) and nuclear fuel (6%).

在美国，各式各样的能源中有27%被用于运输和交通(transportation),38%的能源被用于工业（industry），35%的能源用于居民和商业(residence and commerce)。然而39%的能源产品消耗来源于石油(oil),23%来源于天然气(natural gas)，另外23%来源于煤矿(coal)（见表1—5—1）。

2.3 Future Energy Needs 未来能源需求

传统的能源主要是以下三种化石能源：石油、天然气和煤矿(petroleum, natural gas and coal)。在未来，一些新能源将会被更好地开采和利用，比如精煤(clean coal)、甲烷水化合物(methane hydrates)、油页岩(oil shale)和含油砂(tar sands)。

2.3.1 Clean Coal精煤

原煤经过洗煤，除去煤炭中的杂质，就得到了精煤。

Clean coal technology is considered as processes that reduce the negative environmental effects of burning coal, which wash the coal to remove minerals and impurities and capture the sulfur dioxide and carbon dioxide from the flue gas.

图1—5—1为精煤生产的流程图：

图1—5—1 精煤生产的流程图

2.3.2 Methane Hydrates 甲烷水合物

甲烷水合物又叫可燃冰。甲烷气体和水分子形成结晶，若二者分离可以得到天然气，是在高压低温的条件下形成的。甲烷水合物大多存在于地球两极的永久冻结带和大陆架海底地层。

Methane hydrates form at low temperature and high pressure. And they are found on land in permafrost regions and beneath the ocean floor. Some people believe that methane hydrate will provide energy for hundreds or thousands of years.

2.3.3 Oil Shales 油页岩

油页岩跟煤炭、石油、天然气等化石能源一样属于不可再生能源。油页岩是一种含有可燃有机质的沉积岩，由于其灰分超过40%而不同于煤炭。低温干馏油页岩可提取出页岩油，页岩油类似原油，可以制成汽油、柴油等燃油。目前只有少数国家开采油页岩，美国被认为是油页岩最丰富的国家之一。

Oil shales contain an organic material—kerogen, which may convert to oil after heating. Surface mining of oil shale impacts the environment negatively. Although the world has large oil shale reserves, the environmental pollution, acid rain and global warming are still big problems.

2.3.4 Tar Sands 含油砂

含油砂是一种地下沙层，含有天然沥青，可以被提炼成为石油等。目前含油砂分布广泛，资源丰富，已经成为全球备受关注的能源资源，受到投资者的青睐。

Tar sands contain bitumen which could be converted to oil. Most of the tar sand deposits are located in Canada and Venezuela.

3 Fossil Fuel Resources and Use 化石能源和利用

3.1 Coal 煤炭

煤炭是分布最广泛的化石能源。有地表采煤和地下采煤两种开采煤矿的主要形式。煤炭的燃烧对环境的污染巨大（图1—5—2）。

Coal is the most abundant fossil fuel, used to produce most of the world's electricity. Burning coal produces more carbon dioxide than other fossil fuels. Coal formation begins with peat, heat and pressure squeeze the water from the peat, and initiates a series of transformations from lignite to sub-bituminous coal to bituminous coal to anthracite coal. Anthracite coal has the highest energy density, and peat has the lowest.

3.2 Crude Oil or Petroleum 原油或石油

原油指由地下开采出来的天然石油，主要成分是烷烃。原油是一种混合液体，需要分离、提纯后燃烧产生大量的能量。石油的开采和提炼对环境影响巨大（图1—5—3）。

Crude oil is formed from the remains of ancient marine organisms that were buried beneath sediments and subjected to high temperatures and pressure. Oil is usually found trapped in a layer of porous sandstone or break in the layers of crust. Oil is a mixture of many different liquids and gases, whose components are used to provide energy for a variety of purposes. Its liquid components such as fuel oil and gasoline, are used for home heating and transportation. Because it is a mixture of liquids, crude oil requires a separation and purification step between extraction and use that is not required of the other fossil fuels. This step takes place at an oil refinery and it makes use of a process called fractional distillation, which separates liquids based on differences in their boiling points.

3.3 Natural Gas 天然气

天然气是一种混合气体，主要成分也是烷烃。天然气相对煤炭、石油等能源来说使用安全，对环境污染较小（图1—5—4），因为燃烧后无废渣、废水产生。但是运输起来比较困难，成本较高。天然气可以转化成为液化气，以便于运输。

Mostly methane (CH4), natural gas is formed and found alongside crude oil and coal. Like coal, it is used in power plants to produce electricity, additionally it is commonly used for cooking, and space heating. Burning natural gas produces less carbon dioxide per unit of energy than either of the other fossil fuels. Because it is a gas, natural gas is difficult to transport great distances. Pipelines are used to transport natural gas over hundreds or thousands of miles, but they are expensive, unaffordable in many developing nations, and subject to sabotage. Natural gas can be converted to liquefied natural gas (LNG) when placed under pressure at low temperatures. This makes it more convenient to transport large distances, but requires energy to compress, refrigerate, and transport the gas.

3.4 Other Nonrenewable Fossil Fuels 其他化石燃料

Synfuels 合成燃料：Synfuels are liquids and gases that are produced from coal by processes called coal liquefaction and coal gasification. Like oil shale and tar sands, synfuels take a large quantity of energy to produce and result in a correspondingly low net energy yield.

3.5 Advantages of Coal and Disadvantages of Gas煤炭的优点和天然气的缺点（表1—5—2）

4 Nuclear Energy 核能

4.1 Nuclear Energy 核能

核能也叫原子能，是原子核内部结构发生变化而释放出的巨大能量。核能是不可再生资源，核能的使用对环境的影响巨大，引起各国的关注。

A nonrenewable resource with significant environmental and social costs associated the extraction, processing, use, and disposal of radioactive nuclear fuel.

4.2 Nuclear Fission 核裂变

核裂变是重核分裂的过程。

It is used to produce steam to drive a turbine that turns a generator that produces electricity.

●Nuclear fuel 核燃料

当铀-235的原子核受到外来中子轰击时，一个原子核会吸收一个中子，分裂成两个质量较小的原子核，同时放出2～3个中子。裂变产生的中子又去轰击另外的铀-235原子核，引起新的裂变。

Uranium is mined from the earth and enriched to increase the concentration of the fissionable U-235 isotope. This enriched uranium is used in fuel rods that are placed into the reactor core.

●Moderator 减速剂

It is used to slow down neutrons that are released during the fission reactions.

●Control rods 控制棒

They are often graphite, absorb neutrons and regulate the rate reaction and energy produced.

4.3 High-level Radioactive Waste 放射性废物

It includes the used fuel rods are removed from the reactor core. There is no long-term disposal site presently available, and high-level radioactive waste is stored on-site.

4.4 Advanced Light-water Reactors and Pebble-bed Modular Reactors 先进轻水反应堆和卵石床反应堆

Advanced light-water reactors and pebble-bed modular reactors are less susceptible to accidents and meltdowns. They eliminate many of the safety concerns associated with the operation of the plant, however not the environmental and social costs associated with the production and disposal of nuclear fuel.

4.5 Nuclear Fusion 核聚变

Nuclear fusion is the type of reaction that generates the sun's energy. It has yet to yield a viable solution to solve the world's energy needs and is not expected to do so before fossil fuel resources are exhausted.

5 Hydroelectric Power 水力发电

5.1 Hydroelectric Power 水力发电

水力发电指利用水势的高低落差，配合水轮发电机，从而得到电力。

Hydroelectric power makes use of the potential energy of water stored in an elevated reservoir. Water released from the reservoir is made to flow through turbines that are connected to generators that produce electricity. Hydropower produces more energy than any other renewable energy source in the world—about 25% of the world's electricity.

●Dams 大坝

利用河流资源建立水利枢纽。

The environmental and societal costs of the large dams are needed to store water for reliable hydroelectric energy production.

●Flooding 洪水

Flooding refers to the damage of habitat upstream from the dam. (Catastrophic flooding could result from collapse of the dam)

●Habitat fragmentation 生境破碎

生境破碎指由于在河流上建立水利枢纽，改变了生物生境的形状、类型及在景观中空间排列的现象。

The river ecosystem will be damaged. Fragmentation prevents large ranging or migratory species, such as salmon and river dolphins, from accessing part of their habitat. (The human communities will be displaced when... homes are flooded to create the water storage reservoir.)

●Water-borne infectious diseases 由水传播的传染病

Water-borne infectious diseases are spread in slow-moving and stagnant water behind a dam.

●Sedimentation 沉淀

Sediments are normally carried downstream by a river, accumulate behind dams, resulting in silting. Silt can be removed by dredging; if the sediments are not removed, they will accumulate until the dam is no longer functional.

5.2 Advantages and Disadvantages of Hydroelectric Power水力发电的利弊（表1—5—3）

6 Energy Conservation 能源节约

6.1 Energy Conservation 能源节约

Some strategies can reduce the amount of energy that is used.

●Decrease energy for transportation 减少交通消耗的能源

a. Reduce driving by using mass transit, walking, or riding a bike.

b. Join a carpool. Walk up and down stairs instead of using an elevator.

c. Buy locally grown food and locally made products to reduce the energy required to transport goods to market.

d. Replace a gas-guzzling car with a hybrid-electric or electric vehicle.

●Decrease energy for heating 减少供暖

a. Decrease the thermostat setting when it is cold and wear warmer clothing while indoors.

b. Use less hot water and take cooler, shorter showers.

c. Increase the amount of insulation in a home to reduce heat loss.

d. Replace single-paned with multi-paned windows.

e. Reduce heat loss by improving the seals around windows and doors. Replace a hot water heater that stores hot water in a tank with a tankless hot water heater.

f. Install an active solar energy system to replace a furnace and hot water heater.

●Decrease electricity use 减少电力使用

a. Turn off lights when leaving a room. Increase the thermostat setting when it is hot to reduce the use of an air conditioner.

b. Replace incandescent light bulbs with fluorescent bulbs.

c. Unplug electronics that have a standby mode when they are not in use, or plug them into a power strip and turn off the power strip when appliances are not in use.

d. Install photovoltaic solar panels to provide electricity.

6.2 Energy Efficiency 能量效率

Efficiency is the ratio of the quantity of work or energy that is produced to the quantity of energy that was used. Several of the conservation measures listed above are effective because they increase the energy efficiency of an action.

6.3 Corporate Average Fuel Economy (CAFE) Standards 公司平均燃料经济标准

Enacted by the US Congress in 1975, it requires automobile manufacturers to produce cars that meet a minimum fuel efficiency standard. CAFE standards raised the average mileage for US cars from 13 miles per gallon (mpg) in 1973 to 22 mpg in 1985. But a relaxation of standards in the mid-80s coupled with loopholes in the law and a changed mix of vehicles in the national fleet kept the average at 22 mpg until 2008 when new legislation was passed that will raise the standard to 35 mpg by 2020.

6.4 Hybrid-electric Vehicles 混合动力汽车

Hybrid-electric vehicles use a relatively small amount of gasoline by combining an electric motor with a small gasoline engine for vehicle propulsion. Some of the kinetic energy of the car is used to drive an alternator that charges the batteries needed to power the electric motor. Hybrid-electric vehicles can have efficiencies several times that of a typical automobile getting up to 40～50 mpg.

6.5 Electric Vehicles and Plug-in Hybrid Vehicles 电动汽车和插电式混合动力汽车

These vehicles use electricity to charge batteries in the car. Ideally, this electricity would be generated using an alternative energy source like solar or wind; however, if the electricity was produced by a coal or natural gas fired power plant, fossil fuels are still consumed indirectly. By diverting the energy generation from the internal combustion engine of the car to a power plant, the consumer is trading off some of the environmental costs of operating a gasoline vehicle with those of operating the power plant.

7 Renewable Energy 可再生能源

7.1 Solar Energy 太阳能

人类所需能量的绝大部分都直接或间接地来自太阳。风能、水能、化学能都是由太阳能转化而来的。

7.1.1 Types分类

●Passive solar energy 被动式太阳能

Passive solar energy technology makes direct use of sunlight to heat a building.

●Active solar energy 主动式太阳能

Active solar energy technology makes use of pumps to move water or a fluid-like antifreeze through solar collectors, where it is heated by the sun and then pumped throughout a building to provide heat.

7.1.2 Ways of Utilizing Solar Energy 利用太阳能的方式

●Photovoltaic cells 光电管

They convert sunlight directly into electricity. They are useful in remote locations far from an electrical grid but are less effective in northern latitudes where sunlight is less intense.

●Solar power plants 太阳能发电站

Mirrors are mounted and they use motors in such a way that they track the sun during daylight hours. They require large areas of land with arid climates and intense sunlight throughout the year, which limits ideal locales to deserts. There are habitat loss results in the area where the plant is built.

●Long parabolic mirrors 长柱状反光镜

There is a pipe running along the focus of the mirrors filled with a fluid that is heated by the concentrated sunlight. The heated fluid is used to heat water to produce the steam necessary to generate electricity.

●Solar power tower 塔式太阳能发电站

Solar power tower makes use of an array of mirrors to focus sunlight at a single point where it heats a fluid. The heated fluid is used to heat water to produce the steam necessary to generate electricity.

7.2 Wind Energy 风能

●The cause of wind energy风能的产生

由于地球表面受太阳辐射后温度变化不同，空气中的水蒸气含量也不同，使得各地气压不同，于是大量的空气由高压地区流向低压地区，产生动能。

Wind farms have been built on mountain ridges, passes, and other locations with concentrated reliable winds. Offshore wind farms may also increase the generation of electricity from wind.

表1—5—4列出了风能的优缺点。

7.3 Geothermal Energy 地热能

7.3.1 The Cause of Geothermal Energy地热能的产生

人们可以利用地球内部的天然热能来加热或者发电。

People make use of the earth's internal temperature by tapping into high-temperature, high-pressure steam below the earth's surface. The heat is used to heat buildings and to generate electricity.

7.3.2 Advantages and Disadvantages of Geothermal Energy地热能的优缺点（表1—5—5）

7.4 Biofuels生物燃料

7.4.1 The Cause of Biofuels生物燃料的产生

生物燃料来自一切有生命的动物、植物、微生物。生物燃料可以替代汽油、柴油等能源物质。

Different energy sources all involve obtaining fuel from plant matter and animal waste.

●Methane digesters 沼气池

Methane digesters are used to convert animal waste from feedlots and factory farms into methane. Landfills and wastewater treatment facilities can collect the methane that is produced during decomposition. The methane from either source can be used to produce electricity.

●Sugar cane, corn, and other crops 甘蔗、玉米等农作物

They can be fermented into ethanol and can be used in automobiles.

●Biodiesel fuel生物柴油

Made from vegetable oil, oil squeezed from algae, etc., it replaces traditional diesel fuel.

7.4.2 Advantages and Disadvantages of Biofuels生物燃料的优缺点（表1—5—6）

7.5 Hydrogen Fuel Cells 氢燃料电池

7.5.1 The Cause of Hydrogen Fuel Cells 氢燃料电池的产生

氢燃料电池利用化学反应产生所需的电流。

Hydrogen fuel cells use chemical reactions to produce electric current as it is needed. The most common fuel cells use hydrogen and oxygen as reactants and produce water as the only product.

7.5.2 Advantages and Disadvantages of Hydro Fuel Cells氢燃料电池的优缺点（表1—5—7）

7.6 Ocean Waves and Tidal Energy 海浪和潮汐能

7.6.1 The Cause of Ocean Waves and Tidal Energy海浪和潮汐能的产生

海水涨潮和落潮形成不同的水势差。

The currents that flow during changing tides can be used to turn turbines and generate electricity.

7.6.2 Advantages and Disadvantages of Tidal Energy潮汐能的优缺点（表1—5—8）