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Transport and the Urban Environment Topic 2 – Urban Transportation and Energy A – Transportation and Energy Consumption B – Energy, Transportation and Urban Form C – Alternative Sources of Energy for Urban Transportation A Transportation and Energy Consumption 1. Energy in a Mobile World 2. Utility Factors 3. Petroleum Dependency 4. Combustion of Hydrocarbons 5. Energy Consumption A-1 Energy in a Mobile World Nature Energy is movement or the possibility of creating movement. Exists as potential (stored) and kinetic (used) forms. Conversion of potential to kinetic. Movement can be ordered (mechanical energy) or disordered (thermal energy). Major tendency is to move from order to disorder. Importance Human activities are closely dependant to the usage of several forms and sources of energy. Development processes have increased demand and reliance on energy. Human activities are strongly supported by the usage of energy. Overcoming territories in a global economy requires a substantial amount of work. Work related to transfers of goods, people and information has increased significantly. Growing share of transportation in the total energy spent. A-1 Sources of Energy Non-Renewable Chemical • Fossil fuels (Combustion) Nuclear • Uranium (Fission of atoms) Renewable Chemical • Muscular (Oxidization) Nuclear • Geothermal (Conversion) • Fusion (Fusion of hydrogen) Gravity Energy • Tidal, hydraulic (Kinetic) Indirect Solar • Biomass (Photosynthesis) • Wind (Pressure differences) Direct Solar • Photovoltaic cell (Conversion) A-1 Energy Content of some Fossil Fuels (in MJ/kg) Wood Coal Crude Oil Kerosene Ethanol Methanol Methane Natural Gas Gasoline Hydrogen 0 20 40 60 80 100 120 140 9,000 8,000 7,000 6,000 5,000 4,000 3,000 2,000 1,000 19 62 19 65 19 68 19 71 19 74 19 77 19 80 19 83 19 86 19 89 19 92 19 95 19 98 9 19 5 6 19 5 3 19 5 0 0 19 5 A-1 World Fossil Fuel Consumption, 1950-1998 (in million of tons of equivalent oil) A-1 Energy in a Mobile World Energy exists in various forms Mechanical, thermal, chemical, electrical, radiant, and atomic and are all interconvertible. Forms of energy come from sources qualified as renewable and non-renewable. Renewability Based upon the scale of human events and if the source can be replaced during that period. Wood is a renewable biomass energy source as long as adequate conditions are kept for reserves to be replenished. Rates of exploitation / deforestation in a number of areas are so high that biomass may be considered as a non-renewable source in those circumstances. A-1 Energy in a Mobile World Choice of an energy source Energy and work Depend on a number of utility factors. Factors that favors a specific source. Currently favoring the usage of fossil fuels, notably petroleum. Many efforts have been done to alleviate work. Creating more work performed by extra-human agents like motors and the usage of even more energy. Modification of the environment Rendering space suitable for human activities. Clearing land for agriculture. Modifying the hydrography (irrigation). Establishing distribution infrastructure. Constructing and conditioning (temperature and light) enclosed structures. A-1 Energy in a Mobile World Appropriation and processing resources Extraction of agricultural products from the biomass and raw materials (minerals, oil, lumber, etc.) for human needs. Disposal of wastes, which are in an advanced industrial society very work intensive to safely dispose. Modifies products from the biomass, raw materials and goods to manufacture according to economic needs. Over the last 200 years, work related to processing was considerably mechanized (e.g. robotized assembly lines). A-1 Energy in a Mobile World Transfer Movements of freight, people and information from one place to another. Attenuate the spatial inequities in the location of resources by overcoming distance. The less energy costs per ton or passenger - kilometer, the less importance has transfers. Overcoming territories in a global economy requires a substantial amount of work. Work related to transfers of goods, people and information has increased significantly. Growing share of transportation in the total energy spent. The United States is an economy using massive amounts of energy in the transport sector. A-1 Energy in a Mobile World United States Huge consumer of energy. Pattern of consumption is strongly linked to the attributes of the American economy and territory. Accounts for 5% of the global population, but for 25% of the produced energy. Transportation accounts for about 24% of all the energy used in the United States. A-1 Demand for Refined Petroleum Products by Sector in the United States, 1970-1998 (in Quadrillion BTUs) 25 20 Transportation Residential & Commercial Industrial Electric Utilities 15 10 5 0 1970 1975 1980 1985 1990 1991 1992 1993 1994 1995 1996 1997 1998 A-1 Evolution of Energy Sources Mid 21st Century Animal Biomass Coal Oil Natural Gas Nuclear Hydrogen Late 20th Century Early 20th Century Mid 19th Century 15th Century 0% 20% 40% 60% 80% 100% A-1 Energy in a Mobile World 15th Century Mid 19th Century Traditional societies. Rely only on muscular and biomass sources to answer their energy needs. Mainly the characteristics of the Middle Ages and other previous historical periods. Beginning of the Industrial revolution. Considerably modified energy sources. Greater reliance on coal. Early 20th Century Middle of the industrial revolution. Coal is dominant source of energy. Gradual shift towards higher energy content sources like oil. A-1 Energy in a Mobile World End of 20th Century Modern energy intensive society. Contemporary technological developments allowed: Higher occurrence, a better transferability, reliability, storability, flexibility, safety and cleanliness of high energy content sources for a low price. Emphasis on petroleum products as the main provider of energy. Reached the point where the world economy highly depends on the internal combustion engine and supporting industries. A-1 Global Energy Systems Transition, (% of market) 100 Wood Solids Coal 80 Gases 60 Hydrogen 40 Liquids Oil 20 Natural Gas 0 1850 1900 1950 2000 2050 2100 2150 A-2 Utility Factors Nature Favor the usage of petroleum as the main source of energy for transport activities. The utility factors were so convenient that a dependency on petroleum was created. Occurrence Location of energy sources considering the demand. Several energy sources are only available when a transportation system exists Can support transfers between the supply and the demand. Exploitation of oil fields in several regions of the World (Middle East, Siberia, etc.). Only possible when an efficient transportation system based upon pipelines and tankers was established. A-2 Utility Factors Transferability Distance over which an energy source can be transported. Depends on its physical form (solid, liquid or gas), its energy content, and on the available transport technology. Most petroleum products are in a liquid, more or less viscous, form. Offer an efficient form to be transferred. Economies of scale in transportation enhance transferability. A-2 Economies of Scale in Oil Transportation Modern VLCC (305 m) T2 Tanker (153 m) 1942 1975 A-2 Utility Factors Energy content Available energy per weight or volume unit of a source. A low energy content is inadequate when demand is high and concentrated in space. Gasoline and other petroleum products have a high energy content compared to other fossil fuels like coal. Even more when compared to gravity and solar energy. Reliability Continuous availability is an advantage over intermittent sources. Many sources and continuous supply through maritime and land routes have given a relative reliability for petroleum products. A-2 Utility Factors Storability Some contemporary military interventions were performed to insure the reliability of oil sources and their transport. An energy source has an advantage when it can be stored to answer variations in demands and interruptions of supplies. In liquid form, petroleum products are easily stored. Flexibility Capacity of an energy source to answer multiple usage. Petroleum by-products are the basis of whole industrial sectors (petrochemical). Synthesize goods like plastics, pharmaceutical products, and synthetic rubber. A-2 Utility Factors Safety Sources that can be provided and used at low risks (human and environmental) are an advantage. The petrochemical industry presents some risks (accidents during extraction, refining, transport and usage). Oil is considered a safe source of energy for its production and usage. Cleanliness Sources that produce few waste and are cleanly used have an advantage. In regards of other conventional energy sources like coal and wood and of the available technology, oil is cleaner to use and produces a limited amount of waste. A-2 Utility Factors Price Sources at low cost are generally more used. A function of the occurrence, the transferability and the energy content of the source. Massive investments on large scale extraction, refining and transport of petroleum products. Constant supply. Intensive competition from several oil producing countries (although with some monopolistic control - OPEC). Oil price is cheaper than many other sources. A-3 Petroleum Dependency The reliance on petroleum Petroleum products account for more than 97% of the energy consumption by transportation modes. Transportation accounts for a growing share of the oil used. The share of transportation has increased in the and now accounts for more the 55% of the oil used. Since 1973 the price of petroleum has increased significantly. The transport sector consumed 42% of the oil in OECD countries in 1973. This share climbed to 55.1% in 1995. The sprawl of economic activities, notably in urban areas, is strongly linked to this trend. A-3 Oil Energy Consumption by Sector for OECD countries, 1973-1995 55.1 1995 20 6.3 18.6 Transportation Industry Non-Energy Use Other Sectors 1973 42 0% 20% 26.3 40% 60% 6.3 25.3 80% 100% A-3 Petroleum Dependency Impacts of increasing prices Increasing the fuel efficiency of vehicles. Use of alternative sources of energy. A-3 World Oil Production and Demand, 1996 (in m tons) 1000 800 600 400 200 0 North America Latin America Middle East Asia/Oceania Africa -200 -400 -600 Production Demand Balance Western Europe Eastern Europe 30 25 Actual Predicted 20 15 10 5 0 19 00 19 10 19 20 19 30 19 40 19 50 19 60 19 70 19 80 19 90 20 00 20 10 20 20 20 30 20 40 20 50 20 60 20 70 20 80 20 90 21 00 A-3 World Oil Production and Estimated Resources, 19002100 (in billions of barrels) A-3 Cost of Gasoline, United States, 1999 14% Crude Oil 37% 13% Federal and State Taxes Refining costs and profits 36% Distribution, retail & marketing costs and profits A-3 Gasoline Prices, 1978-1999 Selected Countries (current 1998 dollars per gallon) 5 4.5 4 3.5 Japan France United Kingdom Germany Canada United Statesd 3 2.5 2 1.5 1 0.5 0 1978 1982 1986 1990 1994 1996 1997 1998 1999 A-4 Combustion of Hydrocarbons Internal combustion engine Almost all transportation modes depend on the internal combustion engine. For the majority of internal combustion engines, gasoline (C8H18; four strokes Otto-cycle engines) serves as fuel. Other sources like methane (CH4; gas turbines), diesel (mostly trucks) and kerosene (turbofans) are used. Perfect combustion If all internal combustion engines had perfect combustion, emissions and thus environmental impacts of transportation would be negligible (except for carbon dioxide emissions). Combustion in internal combustion engines is imperfect and incomplete. A-4 Combustion of Hydrocarbons Chemical reaction Gasoline Oxygen Carbon Dioxide Water Energy Combustion Complete and perfect combustion of gasoline: (2) C8H18 + (25) O2 = (16) CO2 + (18) H2O + energy Gasoline produces around 46,000 Btu per kilogram combusted. Requires from 16 to 24 kg of air. A-4 Combustion of Hydrocarbons Control or the process Energy released by combustion causes a rise in temperature of the products of combustion. Temperature attained depends on the rate of release and dissipation of the energy and the quantity of combustion products. Air is the most available source of oxygen. Air also contains vast quantities of nitrogen. Nitrogen becomes the major constituent of the products of combustion. Rate of combustion may be increased by finely dividing the fuel to increase its surface area and hence its rate of reaction. Mixing it with the air to provide the necessary amount of oxygen to the fuel. A-4 Combustion of Hydrocarbons Imperfect combustion Gasoline Sulfur Benzene Air Nitrogen Oxygen Combustion Carbon Dioxide Carbon monoxide Nitrogen Water Oxides Energy VOC + HC The fuel and the oxider are not pure. Gasoline is known to have impurities Sulfur (0.1 to 5%). Sometimes lead (anti-knock agent). Other hydrocarbons (like benzene and butadiene). Air is composed of 78% nitrogen and 21% oxygen. A-4 Combustion of Hydrocarbons Consequences of incomplete combustion Incomplete combustion emits other residuals. Because of the technology of the engine. Besides carbon dioxide and water, a typical internal combustion engine will produce: Carbon monoxide (CO). Hydrocarbons (HC; benzene, formaldehyde, butadiene and acetaldehyde). Volatile organic compounds (VOC). Sulfur dioxide (SO2), particulates, and nitrogen oxides (NOx). These combustion products are the main pollutants emitted in the environment by transportation. A-5 Transportation and Energy Consumption Issue Differences between speed, energy costs, mode and type of loads (freight and passengers). Economies of scale play a crucial role in freight transportation Transposed in its general levels of energy consumption. Transportation operators always ponder a compromise between speed (returns in overcoming distance) and energy (costs in overcoming distance). Lowest consumption levels are associated with bulk freight travelling at slow speed (like oil). Compromise of energy over speed. High levels correspond to passengers or merchandises being carried at high velocities. Compromise of speed over energy. Transportation and Energy Consumption 10 Helicopter Car Propeller Jet plane plane Bus Supersonic plane 1 Train .1 Cargo plane Truck Bicycle Gas pipeline Container ship Oil Pipeline Energy costs A-5 Freight Passengers Train .01 Tanker Speed (m/sec) .002 10 30 100 300 1000 A-5 Energy used by transportation 17% Vehicle operation Vehicle maintenance 5% Vehicle manufacture 7% 1% 4% 66% Infrastructure provision Raw material manufacture Energy generation A-5 Transportation and Energy Consumption Car Poor energetic performance. Road transportation consumes 85% of the total energy used by the transport sector in developed countries. Only 12% of the fuel used by a car actually performs work. Exhaust (33%). Cylinder cooling (29%). Engine friction (13%). Transmission and axles (5.5%). Braking (7.5%). A-5 Factors of Fuel Use by Transportation Technology Vehicle efficiency Type of fuel Economics Prices and incomes Fuel Use Infrastructure Provision and Levels of service Urban Form Density and distribution A-5 Typical Energy Use for a Car 8% 12% 6% 13% 32% 29% Momentum Exhaust Cylinder cooling Engine friction Transmission and axles Braking A-5 Average Gasoline Consumption for New Vehicles, United States, 1972-2001 (in miles per gallon) 30 28 26 24 22 20 18 16 Cars Light Trucks Average 14 12 00 20 98 19 96 19 94 19 92 19 90 19 88 19 86 19 84 19 82 19 80 19 78 19 76 19 74 19 19 72 10 A-5 Light-Duty Vehicles Sales in the United States, 19752001 (in 1,000s) 18000 Trucks Cars 16000 14000 12000 10000 8000 6000 4000 2000 0 75 9 1 77 9 1 79 9 1 81 9 1 83 9 1 85 9 1 87 9 1 89 9 1 91 9 1 93 9 1 95 9 1 97 9 1 99 9 1 01 0 2 A-5 Change in Average Vehicle Characteristics, 1981-2001 (in %) 90 80 70 60 50 40 30 20 10 0 -10 Fuel Economy Weight Horsepower Acceleration A-5 Average Miles per Gallon Traveled by Road Vehicle in the United States, 1996 Average Heavy trucks Light trucks Buses Motorcycles Passenger cars 0 10 20 30 40 50 A-5 Energy Consumption by Mode of Transportation in the United States (in Trillion BTU) 25,000 20,000 Pipeline Water Rail Transit Road Air 15,000 10,000 5,000 0 1970 1975 1980 1985 1990 1991 1992 1993 1994 1995 1996 20,000 18,000 16,000 Bus 14,000 12,000 10,000 8,000 6,000 4,000 2,000 0 19 70 19 75 19 80 19 85 19 90 19 91 19 92 19 93 19 94 19 95 19 96 A-5 Energy Consumption by Road Transportation in the United States (in Trillion BTU) Combination Truck Single-Unit 2-Axle 6-Tire or More Truck Other 2-Axle 4-Tire Vehicle Passenger Car & Motorcycle B Energy, Transportation and Urban Form 1. The Notion of Distance 2. Factors Affecting Distance Traveled A-1 Factors Affecting Distance Traveled Trends The distance traveled has increased over the last 20 years in developed countries. Predominantly in urban areas. VMT (VKT) Vehicle-Miles Traveled (or Vehicle-KM). Important measure of the usage of energy by transportation. Has increased 3% per year on average since 1970. Growth systematically higher than population growth and GDP growth. VMT growth has been linked to a set of factors. A-1 Factors Affecting VMT Growth Vehicle Ownership Population Vehicle Occupancy Age VMT Economic Activity Trip Length Spatial Structure Cost of Driving Alternatives available A-2 Factors Affecting Distance Traveled Population and economic activity Both a dominant factor. Population growth is accompanied by an increase in urban travel. Economic activity, often expressed by GDP, is linked with increasing urban travel. Wealthier population can afford to travel more often and over longer distances. Increased consumption requires added deliveries of goods and resources. Vehicle ownership Access to a personal vehicle promotes its use. Correlated with the wealth of the population. From 1969 to 1995, the number of vehicles per household has increased from 1.2 to 1.8 in the United States. A-2 Annual Growth Rates of VMT, Population and GDP, 1970-1995, United States GDP Population VMT 1990-95 1985-90 1980-85 1975-80 1970-75 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 A-2 Changes in Population, GDP and VMT, 1969-1995, United States (1969=100) 240 220 VMT Population GDP 200 180 160 140 120 100 1969 1977 1983 1990 1995 A-2 Factors Affecting Distance Traveled Location of population Age of the population Significant changes in the location of the population, notably in developed countries. New spatial structures, such as sub-urbanization. Lower average population densities. Strong correlation between age and mobility. People over 65 are on average 40% less mobile than people between 35 and 54. Aging of population will slow VMT growth. Trip length Correlated with locational changes in population. Longer distances between home and place of work. A-2 Annual VMT by Age Group and Gender, United States, 1995 20,000 18,000 16,000 14,000 12,000 Males Females 10,000 8,000 6,000 4,000 2,000 0 16-19 20-34 35-54 55-65 65+ A-2 Home-to-Work Commute Profile, United States, 19831995 40 35 33.6 32.3 30 28 25 20 18.2 15 10.6 10 20.7 19.7 11.6 8.5 5 0 1983 1990 1995 Average Length of Work Trips (miles) Average Work Trips Travel Time (minutes) Average Speed (Miles per Hour) A-2 Factors Affecting Distance Traveled Vehicle Occupancy Cost of driving Reflects the intensity of use of private and public urban transportation. Dropped significantly in most developed countries. The most significant drop was for work-related trips. Act as a deterrent. Involve several costs such as car ownership, insurance, maintenance, taxes and fuel. Have remained similar over the last 25 years. Alternatives available Involve public transit, walking, cycling, carpooling or working at home. A-2 Vehicle Occupancy by Purpose, 1977-1995, United States Average Work 1995 1977 Family / Personal Social / Recreation 0.0 0.5 1.0 1.5 2.0 2.5 3.0 C Alternative Sources of Energy for Urban Transportation 1. Context 2. Alternative Fuels A-1 Context Emergence Received increasing amounts of attention since the first oil crisis in 1973. Attention ebbs and flows with fluctuations in the price of oil. Several of alternate sources need further research before they can become truly viable alternatives. Moving from carbon-based sources to non-carbon based. Unsustainability of fossil fuels The resource itself is finite; its use contributes to the global warming problem. Some 35% of the carbon emissions in the USA is attributable to electric power generation. Employing substitutes for fossil fuels in that area alone would help alleviate our greenhouse gas problem. A-1 Context Fuel use efficiency Not an alternate energy source but can have a great impact on the conservation side of the ledger. After 1973, many industries were motivated to achieve greater efficiency of energy use. Many appliances (including home air conditioners) were made more energy efficient. The motivation to do this declined during the 1980s with declining energy costs. The USA continually ranks behind Europe and Japan in energy efficiency. Contributes to our lack of competitiveness with those economies. A-1 Context Besides electricity generation, another 32% of the carbon emissions in the USA is due to vehicular use. More fuel-efficient cars would help reduce this amount. Alternate energy sources, such as electricity, might make a greater difference. Require a great behavioral adjustment on the part of the carusing public, especially in the USA. A-2 Alternative Fuels Hydrogen Hydrogen Oxygen Fuel Fuel Cell Fuel cells Catalytic conversion Water Electricity Considered in itself the cleanest fuel. Compose 90% of the matter of the universe. Non polluting (emits only water and heat). Highest level of energy content. Convert fuel energy (such as hydrogen) to electric energy. No combustion is involved. Composed of an anode and a cathode. Fuel is supplied to the anode. Oxygen is supplied to the cathode. Electrons are stripped from a reaction at the anode and attracted to form another reaction at the cathode. A-2 Alternative Fuels Fuel cell cars Most likely replacement for the internal combustion engine. Efficiency levels are between 55% and 65%. Where to get the hydrogen from? Not naturally occurring. Electrolization of water. Electricity from fossil fuels not a environmentally sound alternative. Electricity from solar or wind energy is a better alternative. Extraction from fossil fuels. From natural gas.