Energy

Environmental Science环 境 学 双 语Prof. Ge YingNanjing Agri. Univ.

Review of last class• Population growth• 4 phases (transition); J curve (exponential growth)• Demography• Census, birth rate, fertility rate, death rate, etc.• Population and Environment• Impact on water, land, forest, energy, climate, etc.• Ageing of Population• Decline of fertility rate and death rate• How to control the population growth

Major contents of the courseChapter 1 IntroductionChapter 2 Population and environmentChapter 3 Energy and environmentChapter 4 Air pollution and its controlChapter 5 Sustainable developmentChapter 6 Water pollution and its controlChapter 7 Soil pollution and its controlChapter 8 Noise and solid waste

Energy and environmentWHATTypes of energy; energy crisisWHYHistory and current status of energyconsumption ( 能 源 消 费 的 历 史 和 现 状 )HOWSolutions to energy shortage and pollution( 能 源 短 缺 和 污 染 问 题 的 对 策 )

Important conceptsEnergy ( 能 量 ): The capacity to do work.Work ( 功 ): The application of force througha distance.Power ( 功 率 ): The rate of flow of energy, orthe rate at which the work is done.

Types of energy ( 能 源 的 类 型 )能 源Energy一 次 能 源Primaryenergy二 次 能 源Secondaryenergy常 规 能 源Conventionalenergy新 能 源Newenergy可 再 生 能 源renewable不 可 再 生 能 源nonrenewable可 再 生 能 源renewable不 可 再 生 能 源nonrenewable

Types of Energy• Primary Energy ( 一 次 能 源 )自 然 界 中 能 提 供 现 成 形 式 能 量 的 能 源• Secondary Energy ( 二 次 能 源 )需 要 依 靠 其 他 能 源 来 制 取 的 能 源

Primary EnergyConventional EnergyRenewable — hydropowerNon-Renewable — coal ( 煤 ), petroleum ( 石 油 ),natural gas ( 天 然 气 )New EnergyRenewable — solar, biomass, wind, geothermal,oceanNon-Renewable —nuclear

Secondary EnergyNon-Renewable — electricity ( 电 能 ), gasoline( 汽 油 ), coal gas ( 煤 气 ), etc.Primary to Secondary Energy: conversionefficiency is very low.

We need energy to:

History of energy consumption1 卡 : 使 1 克 水 的 温 度 升 高 1℃ 所 需 要 的 能 量

History of energy consumption• 原 始 时 期 :food is the No. 1 energy• 狩 猎 时 期 :wood is the first consumable energy forliving because human learned how to use fire• 原 始 农 业 时 期 :human use animals in farmingactivities• 先 进 农 业 时 期 :human learned to use coal, producedmachines to obtain wind energy and hydropower• 工 业 时 期 :invention of steam engine; wood wasreplaced by coal and oil• 现 代 技 术 时 期 :development of gas energy ( 内 燃 机 )and use of electricity

Energy Demand IncreasesAs World Population GrowsPopulation,Billion Persons10864219702005202500 200 400 600 800Energy Consumed, Quadrillion BTU1 BTU =1055joules( 焦 耳 )Quadrillion: 千 的 五 次 方1970 to 2025Source: U.S. Department of Labor 2001 Occupational EmploymentStatistics; EIA, International Energy Outlook, 2004

Energy ConsumptionHow much energy do we use every year?700History Projections60055550450045440340036634430930028424320720061210001970 1975 1980 1985 1990 1995 2000 2005 2010 2015 2020

Energy consumption and living quality( 能 源 消 耗 与 生 活 质 量 )• How much energy a person should consume?• Living quality can be measured by humandevelopment index (HDI).• HDI uses 3 types of index: life expectancy,education and GDP. It varies from 0 to 1.

Energy consumption and living quality( 能 源 消 耗 与 生 活 质 量 )人 口 不 少 于 100 万 的 国 家人 均

Energy consumption and living quality( 能 源 消 耗 与 生 活 质 量 )• What do you see from the figure?• Living quality increases with the increase ofelectricity consumption per capita.• However, this increase is not linear ( 线 性 ).

Energy consumption and living quality( 能 源 消 耗 与 生 活 质 量 )人 口 不 少 于 100 万 的 国 家人 均

Energy consumption and living quality( 能 源 消 耗 与 生 活 质 量 )人 口 不 少 于 100 万 的 国 家人 均

Energy consumption and living quality( 能 源 消 耗 与 生 活 质 量 )• What do you see from the figure?• Living quality increases with the increase of energyconsumption per capita.• However, this increase is not linear ( 线 性 ).• Interestingly, there are several countries with highlevel of energy consumption but low HDI (~ 0.8).

Energy consumption and living quality( 能 源 消 耗 与 生 活 质 量 )人 口 不 少 于 100 万 的 国 家人 均

Energy consumption and living quality( 能 源 消 耗 与 生 活 质 量 )• Reasons for this phenomenon– Small population in these countries– A large amount of poor people in thepopulation, lowering HDI

Worldwide Commercial Energy Productionoil ( 石 油 ), coal ( 煤 ), gas ( 天 然 气 ), solar ( 太 阳 能 ), hydro ( 水 能 )wind ( 风 能 ), wood ( 木 材 ), peat ( 泥 煤 ), charcoal ( 木 炭 ), manure ( 堆 肥 )

Fossil fuels ( 化 石 燃 料 )• Solid: coal, world deposits 10 timesgreater than oil and gas resourcescombined• 可 燃 成 分 : carbon and hydrogen

Increasing heat and carbon contentIncreasing moisture contentPeat 泥 炭(not a coal)Lignite 褐 煤(brown coal)Bituminous Coal 烟 煤(soft coal)Anthracite 无 烟 煤(hard coal)HeatHeatHeatPressure Pressure PressurePartially decayedplant matter in swampsand bogs; low heatcontentLow heat content;low sulfur content;limited supplies inmost areasExtensively usedas a fuel becauseof its high heat contentand large supplies;normally has ahigh sulfur contentHighly desirable fuelbecause of its highheat content andlow sulfur content;supplies are limitedin most areas

Where are the coal reserves?

Surface Mine: 露 天 采 煤

Underground Mine: 地 下 采 煤

煤的优缺点AdvantagesAmple supplies(225–900 years)High net energyyieldLow cost withhuge subsidies( 补 助 )Mining andcombustiontechnologywell-developedAir pollution canbe reduced withimprovedtechnology (butadds to cost)DisadvantagesVery highenvironmentalimpactSevere landdisturbance, airpollution, andwater pollutionSevere threat tohuman healthHigh land useHigh CO 2emissionswhen burnedReleasesradioactiveparticles andmercury into air

SubsurfaceMine OpeningAcid drainage fromreaction of mineralor ore with waterRunoff ofsedimentSurface MinePercolation to groundwaterLeaching of toxic metalsand other compoundsfrom mine spoilpercolation: 下 渗leaching: 沥 滤runoff: 径 流sediment: 沉 积 物drainage: 排 水 ore: 矿 石spoil: 矸 石Leaching may carryacids into soil andgroundwatersupplies

Fossil fuels ( 化 石 燃 料 )• Liquid: petroleum, most used fossilfuel in developed countries

Where are the oil reserves?

Gases天 然 气石 油 的 分 馏Gasoline汽 油lightAviation fuel航 空 油Heating oil燃 料 油Heatedcrude oilDiesel oil柴 油Naphtha石 脑 油FurnaceGreaseand waxAsphalt油 脂 、 蜡沥 青heavy

AdvantagesDisadvantages石油的优缺点Ample supply for42–93 yearsLow cost (withhuge subsidies)High netenergy yieldEasily transportedwithin andbetween countriesLow land useEfficient distributionsystemNeed to findsubstitute within50 yearsArtificially lowprice encourageswaste anddiscouragessearch foralternativesAir pollutionwhen burnedReleases CO 2when burnedWater pollution

Fossil fuels ( 化 石 燃 料 )• Gas: natural gas, world’s 3rdlargest commercial fuel; produceless CO 2 compared to coal and oil• Main component: methane ( 甲 烷 )

Where are the natural gas reserves?

天然气的优缺点AdvantagesAmple supplies(125 years)High net energyyieldLow cost (withhuge subsidies)Less air pollutionthan other fossilfuelsLower CO 2emissions thanother fossil fuelsModerate environmentalimpactEasily transportedby pipelineLow land useDisadvantagesNonrenewableresourceReleases CO 2when burnedMethane(a greenhousegas) can leakfrom pipelinesDifficult to transferfrom one countryto anotherSometimesburned off andwasted at wellsbecause of lowpriceNeeds pipelines

可 燃 冰 (flammable ice)• CH 4·H 2 O( 水 合 天 然 气 ), new energy in 21 st century• Formation: similar to oil and natural gas, but lowtemperature and high pressure are necessary.• 1 m 3 = 164 m 3 natural gastotal energy = 2-323 times of the sum of coal, oil andnatural gas.

Precautions• Difficulty with extraction of flammableice.• May speed up global warming if CH 4 isreleased into the atmosphere.