Final Exam Review.pdf

25 Pages
268 Views
Unlock Document

Department
Environmental Studies
Course
ES102
Professor
Edmund Okoree
Semester
Summer

Description
Lesson 7: Nonrenewable Energy Resources 17-1: Evaluating Energy Resources What Types of Energy Do We Use? Supplementing Free Solar Capital • 99% of the energy that heats the Earth and our homes comes from the sun ◦ The remaining 1% comes mostly form burning fossil fuels • Solar energy (solar capital) comes from the nuclear fusion of hydrogen atoms that make up the sun's mass • Indirect forms of renewable solar energy: wind, falling and flowing water (hydropower) and biomass (sola energy converted to chemical energy stored in chemical bonds of organic compounds in trees and other plants) • The remaining 1% of energy we use is commercial energy ◦ It comes from extracting and burning nonrenewable mineral resources form the Earth's crust ◦ Oil, natural gas, coal What Types of Commercial Energy Does the World Depend On? • 84% comes from nonrenewable energy resources ◦ e.g.) Fossil fuels • 14% comes from renewable energy resources ◦ e.g.) Biomass, hydropower, geothermal, wind, and solar energy ◦ Biomass energy is renewable as long as wood supplies are not harvested faster than they are replenished Why Is the Energy Future of the United States Important to Canada? • The future direction of U.S energy policy will have important environmental and economic consequences for Canada • The need to use cleaner and less climate-disrupting (noncarbon) energy resources – not the depletion of fossil fuels – is the driving force behind the projected transition to a solar-hydrogen energy age in NAand throughout the world before the end of this century • The reduction in U.S use of oil would have negative consequences for the production of oil from Alberta's oil sands ◦ However, lower U.S oil consumption would benefit Canada as a whole by reducing both cross-border air pollution and global political tensions stemming from U.S over-dependence on the oil resources of the Middle East How Can We Decide Which Energy Resources To Use (See questions on page 373) What Is Net Energy? • Net energy is the total amount of energy available from the resource minus the energy needed to find, extract, processes, and get it to consumers ◦ It is calculated by estimating the total energy available from the resource over its lifetime minus the amount of energy used (first law of thermodynamics), automatically wasted (second law of thermodynamics), and unnecessarily wasted in finding, processing, concentrating, and transporting the useful energy to users ◦ It can be expressed as a ratio of useful energy produced to the useful energy used to produce it ▪ e.g.) 10/ 8 or 1.25 17-2: Oil What Is Crude Oil, and How Is It Extracted and Processed? • Petroleum, or crude oil, is a thick and gooey liquid consisting of hundreds of combustable hydrocarbons along with small amounts of sulphur, oxygen, and nitrogen impurities • We have oil today because of three events: ◦ The first occurred when sediments buried dead organic material raining down onto seafloors faster than it could decay ◦ The next took place eons later when the seafloor sediments ended up with the right depth for pressure and heat to slowly “cook” or convert the buried organic material into oil ◦ The third came about because the oil was able to collect in porous limestone or sandstone rock covered by an impermeable cap of shale or silt to keep it form escaping and thus making it and other fossil fuels part of the carbon cycle ▪ Any change in this chain of events would have meant no oil • The oil and natural gas which provides energy to heat our homes and run our cars is called conventional oil • Deposits of crude oil and natural gas are trapped together under a dome deep within the Earth's crust on land or under the seafloor ◦ The crude oil is dispersed in pores and cracks in underground rock formations ◦ Awell is drilled into the deposit to extract the oil ◦ Then oil drawn by gravity out of the rock pores and into the bottom of the well is pumped to the surface ◦ After it is extracted, it is transported to a refinery by pipeline, truck, or ship ◦ Some products of oil distillation, petrochemicals are used as raw materials in manufacturing pesticides, medicines, plastics, synthetic fibres and paint Who Has The World's Oil Supplies? • The 12 countries that make up the Organization of the Petroleum Exporting Countries (OPEC) have at least 60% of the world's estimated crude oil reserves • Members: ◦ Algeria,Angola, Ecuador, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, SaudiArabia, UnitedArab Emirates, and Venezuela • SaudiArabia has the largest proportion of the world's proven oil reserves (22%) followed by Canada (14%) Case Study: How Much Oil Do Canada and the US Have? • Canada's oil reserves are concentrated inAlberta • Another area of high potential is the East Coast Hibernia oil field and the nearby White Rose and Terra Nova oilfields • Canada ships 30% of its production to the US, keeping 70% for domestic use • Canada has a surplus of natural gas How Long Will Conventional Oil Supplies Last? • Known and projected global oil reserves should last 42 – 93 years depending on how rapidly we use oil • M. King Hubbert: “Hubbert's Peak” looked like a bell curve, predicting that oil production in the US would peak in the 1970s Case Study: Why Has the Arctic Suddenly Gained World Attention? • In recent years, theArctic sea ice has melted to unprecedented levels, opening one of the world's least explored regions to oil and gas discovery What Are the Major Advantages and Disadvantages of Conventional Oil? • Conventional oil is versatile fuel and reserves can last up to 50 years, but burning it produces air pollution and releases the GHG carbon dioxide • Advantages: ◦ Ample supply for 42 – 93 years ◦ Low cost (with huge subsidies) ◦ High net energy yield ◦ Easily transported ◦ Low land use ◦ Technology is well developed ◦ Efficient distribution system • Disadvantages: ◦ Need to find substitute within 50 years ◦ Artificially low prices encourages waste and discourages search for alternatives ◦ Air pollution when burned ◦ Releases CO2 when burned ◦ Moderate water pollution How Useful Are Heavy Oils from Oil Sand and Oil Shale? • Oil sand or tar sand is a mixture of clay, sand, water, and bitumen (a combustable organic material – thick and sticky heavy oil with a high sulphur content) • Oil sands near the surface are dug up and mixed with hot water and steam to extract the bitumen, which is heated in huge cookers to convert it into a low-sulphur synthetic crude oil suitable for refining ◦ Heating the cookers requires vast amounts of natural gas that reduces the net energy yield for the oil • When the oil sands are too deep for open-pit mining: ◦ Cyclic steam stimulation involves softening the bitumen with steam and then extracting it ▪ This method uses a vertical well to inject steam and extract bitumen ◦ Steam-assisted gravity drainage involves two horizontal wells: ▪ The upper well injects steam while the lower well extracts the condensed steam and softened bitumen ◦ Vapour extraction uses solvents such as butane to dilute and extract the bitumen without the need for energy-expensive steam ◦ Toe-to-heel air injection involves igniting bitumen underground in order to soften the surrounding bitumen enough to pump • To date, the largest oil sands projects are operated by Syncrude and Suncor (surface mines) • Oil shales are fine-grained sedimentary rocks containing a solid combustible mixture of hydrocarbons called kerogen ◦ It can be distilled from crushed oil shale rock by heating it in a large container to yield shale oil ◦ See advantages and disadvantages page 384 17-3: Natural Gas What Is Natural Gas? • In its underground gaseous state, natural gas is a mixture of methane, ethane, propane, butane and small amounts of hydrogen sulphide • Conventional natural gas lies above most reservoirs of crude oil ◦ Natural gas was formed from fossil deposits of phytoplankton and animals buried on the seafloor for millions of years and subjected to high temperatures and pressures ◦ Deposits of natural gas found above oil deposits cannot be used • Unconventional natural gas is found in other underground surfaces ◦ One is methane hydrate, in which small bubbles of natural gas are trapped in ice crystals deep under theArctic permafrost and beneath deep-ocean sediments • When a natural gas field is tapped, propane and butane gases are liquefied and removed as liquefied petroleum gas (LPG) • At a very low temperature natural gas can be converted to liquefied natural gas (LNG) ◦ This highly flammable liquid can then be shipped in refrigerator tanks How Is Natural Gas Used? • Natural gas can be burned to heat space and water, generate electricity, and propel vehicles • Increasingly, natural gas is used to run medium-sized turbines that produce electricity Who Has the World's Natural Gas Supplies and How Long Will the Supplies Last? • Russia and Iran have almost half of the world's reserves of conventional natural gas • Global reserves should last 62 – 125 years • They project that conventional and unconventional supplies of natural gas should last at least 200 years at the current consumption rate, and 80 years if the consumption rate rises 2% per year What Is the Future of Natural Gas in Canada and the US? • Natural gas production in the US is expected to continue declining, whereas Canadian production is expected to peak between 2020 and 2030 ◦ Then, Canada, the US and the rest of the world will have to rely on Russia and the Middle East for supplies of natural gas 17-4: Coal What Is Coal, and How Is It Extracted? • Coal is a solid fossil fuel formed in several stages as buried remains of land plants ◦ It mostly contains carbon and small amounts of sulphur ◦ Anthracite is the most desirable type of coal because of its high heat content and low sulphur content ▪ However, it takes longer to form, is less common, and therefore more expensive ◦ Coal is mostly used by power plants and industrial plants How is Coal Used, and How Long Will Supplies Last? • Coal is burned mostly to produce electricity and steel • Reserves in US, Russia and China could last for hundreds of years • Coal is the world's most abundant fossil fuels, but mining and burning it has a severe environmental impact on air, water, and land and accounts for a third of the world's CO2 emissions • See advantages and disadvantages on page 387 What Are the Advantages and Disadvantages of Converting Solid Coal into Gaseous and Liquid Fuels? • Solid coal can be converted into synthetic natural gas (SNG) by coal gasification or into a liquid fuel such as methanol or synthetic gasoline by coal liquefaction • Without huge government subsidies, synthetic fuels play a minor role in energy resources • To reduce CO2 emissions during the coal gasification process, researchers hope to develop metal-ceramic membranes that trap carbon dioxide gas ◦ The CO2 could then be compressed and piped off to underground repositories or other permanent storage sites 17-5: Nuclear Energy How Does Nuclear Fission Reactor Work? • In a nuclear fission chain reaction, neutrons split the nuclei of atoms (uranium and plutonium) and release energy mostly as high temperature heat as a result of the chair reactions ◦ The rate of fission is controlled and the heat generated is used to produce high- pressure steam, which spins turbines that generate electricity ◦ Some reactors use water or graphite for a moderator to slow down the neutrons emitted during fission so the chain reaction can be sustained ◦ Other reactors use water or carbon dioxide as a coolant to keep the reactor parts from melting and to produce steam to make electricity What Went Wrong in Chernobyl? • Operators made adjustments to disable the automatic shut-down mechanisms, which would have interfered with their experiment • As the flow of coolant water decreased, there was a surge of power ◦ The fuel elements ruptured and an explosion of steam blew the plate off the reactor ◦ Asecond explosion threw burning fuel and graphite into the air ▪ It burned for 9 – 10 days releasing large amounts of radioactivity into the environment • Chernobyl is known as the largest nuclear power plant disaster See Advantages/ Disadvantages of Conventional Nuclear Fuel Cycle and Coal vs. Nuclear on page 393 How Safe is High-Level Radioactive Waste Stored at Nuclear Power Plants? • Spent fuel rods stored underwater in pools or in dry casks outside of the containment shells at nuclear plants are vulnerable to attack by terrorists • Aspent fuel rod holds 5 – 10 times more long-lived radioactivity than the radioactive core inside a plant's sector • If water drains out of a spent-fuel poor or a dry storage cask ruptures: ◦ Highly radioactive and thermally hot fuel would be exposed to air and steam ◦ This would cause the zirconium outer cover of the fuel assemblies to catch fire and burn fiercely for days ◦ This would release significant amounts of radioactive materials into the atmosphere and contaminate large areas for decades How Do We Dispose of Low-Level Radioactive Waste? • The nuclear fuel cycle and other nuclear facility processes produce low-level radioactive wastes that must be stored safely for 100 – 500 years before they decay to safe levels • Such wastes include tools, building materials, clothing, glassware, and other items that have been contaminated by radioactivity • The nuclear and other industries have produced 2.3 million cubic meters of low-level wastes in Canada ◦ These waste materials are stored in specifically designed aboveground buildings while awaiting a more permanent disposal option ◦ There are plans to build a deep-disposal site at the Bruce Nuclear Plant for low- and medium-level wastes How do We Dispose of High-Level Radioactive Waste? • There is a disagreement among scientists over methods for the long0term storage of high-level radioactive waste • Some proposed methods: ◦ Shoot it into space or into the sun ▪ High cost and a launch accident could disperse high-level radioactive wastes over large areas of the Earth (like the Challenger) ◦ Bury it under theAntarctic ice sheet or the Greenland ice cap ▪ The long-term stability of the ice sheets is unknown ▪ Heat could destabilize it ▪ Prohibited by international law ◦ Dump it into descending subduction zones deep in the ocean ▪ Prohibited by international law ▪ Could be spewed out by volcanic activity ▪ Containers might leak and contaminate ocean before being carried downward ◦ Bury it in thick deposits of mud on the deep-ocean floor in areas that tests show have been geologically stable for 65 million years ▪ Containers would eventually corrode and release radioactive chemicals ▪ Prohibited by international law ◦ Change it into harmless, or less harmful, isotopes ▪ No way exists to do this ◦ Bury it deep underground ▪ Most favoured ▪ Issues: Where to locate site, how to transport, how to avoid long-term unforeseen problems, how to gain public acceptance What Can We Do with Worn-Out Nuclear Plants? • When a nuclear reactor reaches the end of its useful life we have to keep its highly radioactive materials form reaching the environment for thousands of years • When a nuclear plant comes to the end of its useful life, it must be decommissioned ◦ 3 proposals: ▪ Dismantle • How can a nuclear plant be safely dismantled when the plant itself will be radioactive and every took used – even water in the cleanup – will become radioactive waste? ▪ Mothball • Erecting a physical barrier and setting up full-time security for 30 to 100 years before the plant is dismantled • Allows time for radioactive material to decay ▪ Entombment • Enclosing the entire plant in a concrete tomb that must last and be monitored for several thousand years Lesson Eight: Renewable Energy How Can We Use Direct Solar Energy to Heat Houses and Water? • Apassive solar heating system absorbs and stores heat from the sun directly within a structure ◦ Energy efficient windows and attached greenhouses face the sun to collect solar energy by direct gain ◦ Walls and floors of concrete, adobe, brick, stone, salt-treated timber and water in metal or plastic containers store the collected solar energy as heat and release it slowly through the day and night • An active solar heating system absorbs energy from the sun by pumping a heat- absorbing fluid (water or anti-freeze) through special collectors usually mounted on a roof or on special racks to face the sun • Atypical active collector has a flat black surface, a coil through which a heat-absorbing medium such as water is pumped and a cover consisting of two or three layers of glass • Advantages of both: ◦ Energy is free ◦ Quick installation ◦ No CO2 emissions • Disadvantages of both: ◦ Need access to sun 60% of the time ◦ Need heat storage system ◦ Active collectors are unattractive How Can We Use Solar Energy to Generate High-Temperature Heat and Electricity? • Large arrays of solar collectors in sunny deserts can produce high-temperature heat to spin turbines and produce electricity, but costs are high • Australia is building a power tower that will consist of a concrete thermal chimney twice the high of the world's largest building surrounded by a gigantic sloped solar greenhouse • Advantages of solar energy for high-temperature heat and electricity: ◦ Moderate net energy ◦ No CO2 emissions ◦ Fast construction • Disadvantages ◦ Low efficiency ◦ High costs ◦ High land use How Can We Produce Electricity with Solar Cells? • Solar energy can be converted directly into electrical energy by photovoltaic (PV) cells commonly called solar cells • The semiconductor material used in solar cells can be made into lightweight paper-thin rigid or flexible sheets and incorporated into traditional-looking roofing materials • British Petroleum (BP) began building the world's largest factory to produce windows and siding and roofing materials that will incorporate BP's power-producing solar cells • With financing from the World Bank, India is installing solar-cell systems in 38,000 villages • Zimbabwe is bringing solar electricity to 2 500 villages • Advantages of Solar Cells: ◦ High net energy ◦ Work on cloudy days ◦ Quick installation • Disadvantages ◦ Low efficiency ◦ High costs ◦ DC current must be converted toAC How Can We Produce Electricity from Flowing Water? • Solar energy evaporates water and deposits it as water and snow in other areas as part of the water cycle • Water flowing from high elevations to lower elevations in rivers and streams can be controlled by dams and reservoirs and used to produce electricity ◦ This is called hydropower • Hydropower is a major emitter of greenhouse gases ◦ This occurs because reservoirs that power dams can trap rotting vegetation, which can emit GHG such as carbon dioxide and methane ◦ Small-scale hydropower projects eliminate most of the harmful environmental effects of large-scale projects ▪ BUT electrical output varies with seasonal changes in stream flow • Advantages of Large-Scale Hydropower ◦ High efficiency ◦ Long life span ◦ Low-cost electricity • Disadvantages ◦ High construction costs ◦ Danger of collapse ◦ Uproots people Wind Energy • The greater heating of the Earth at the equator than at the poles and the Earth's rotation sets up flows of air called wing • Wind can be captured by wind turbines and converted into electricity • Wind power has increased more than tenfold and is the world's second fastest growing source of energy (after solar cells) • Europe is leading the world into the age of wind energy and out of the age of coal and other fossil fuels • Denmark has banned coal and gets 90% of its electricity from wing • Wind power is also being developed in India and to a lesser degree in China • In Canada, the most powerful and consistent winds are in the East and West coasts ◦ 13 windmill farms have been built in the Maritimes ◦ Agood deal of wind potential exists in the Great Lakes region ▪ Lake Huron • Wind power developers now make sophisticated studies of bird migration paths to help them locate onshore and offshore wind parks and are designing new turbines to reduce this problem • Advantages of wind power ◦ High efficiency ◦ Very low environmental impact ◦ No CO2 emissions • Disadvantages ◦ Visual pollution ◦ Steady winds needed ◦ High land for wind farm Producing Energy from Biomass • Biomass consists of plant materials and animal wastes that can be burned directly as a solid fuel or converted into gaseous or liquid biofuels • Burning wood and manure for heating and cooking supplies about 10% of the world's energy and about 30% used in developing countries (90% in the poorest countries such as Bangladesh, Ethiopia, Burundi, and Bhutan) • Ecologists argue that it makes more sense to use animal manure as fertilizer and crop residues to feed livestock, retard soil erosion, and fertilize the soil ◦ Not allowing these animal and crop wastes to return to the soil as a natural fertilizer can reduce food production and food supplies in poor countries • Produces CO2 (but there is no net increase) • Advantages of Solid Biomass ◦ Plantation can help restore degraded lands ◦ No net CO2 increase if harvested and burned sustainably ◦ Large potential supply in some areas • Disadvantages ◦ Nonrenewable if harvested unsustainably ◦ Plantations could compete with cropland ◦ Soil erosion, water pollution, and loss of wildlife habitat Geothermal Energy • Geothermal energy consists of heat stored in soil, underground rocks, and fluids in the Earth's mantle ◦ e.g.) Volcanic rock, geysers, and hot springs • Three nondepletable sources of geothermal energy: ◦ Hot dry-rock zones ◦ Molten rock ◦ Warm-rock reservoir deposits • The world's largest operating geothermal system, called The Geysers, extracts energy from a dry steam reservoir north of SF, California • Santa Monica, California, became the first city in the world to get all its electricity from geothermal energy • Advantages of Geothermal Energy ◦ Very high efficiency ◦ Low land use ◦ Low land disturbance • Disadvantages ◦ Scarcity of suitable sites ◦ CO2 emissions ◦ Noise and odour Hydrogen • Some energy analysts view hydrogen gas as the best fuel to replace oil during the last half of this century • Three problems with turning hydrogen into fuel as a reality: ◦ First, hydrogen is chemically locked up in water and organic compounds (methane and gasoline) ◦ Second, it takes energy and money to produce hydrogen from water and organic compounds ◦ Third, fuel cells are the best way to use hydrogen to produce electricity, but current versions are expensive • Aproblem is that getting hydrogen from organic compounds such as methane produces carbon dioxide • Hydrogen is highly flammable and burns with an invisible flame • Advantages of Hydrogen ◦ Low environmental impact ◦ Easier to store than electricity ◦ Nontoxic • Disadvantages ◦ Not found in nature ◦ Negative net energy ◦ High costs Lesson Nine: Biodiversity and Forest Resources Concept of Biodiversity and Global Patterns • Increase Factors: ◦ Middle stages of succession ◦ Moderate environmental disturbance ◦ Small changes in environmental conditions ◦ Physically diverse habitat ◦ Evolution • Decrease Factors: ◦ Extreme environmental conditions ◦ Large environmental disturbance ◦ Intense environment disturbance ◦ Severe shortages of key resources ◦ Non-native species introduction ◦ Geographic isolation • Global patterns: ◦ The impact of the human ecological footprint on the Earth's land has disturbed at least half and probably about 83% of the Earth's land surface (excludingAntarctica and Greenland) ◦ 82% of temperate deciduous forests have been cleared, fragmented, and dominated because their soils and climate are favourable for growing food and urban development ◦ Tundra, tropical deserts, and land covered with ice are the least disturbed biomes because their harsh climates and poor soils make them unappealing to most human activities ◦ In Canada, most of the wetlands across the country were lost to agriculture and drainage before wetland programs began ◦ The Carolinian forest of southern Ontario has been reduced to remnants in few places like Pelee National Park ◦ Humans use, waste, or destroy about 10 – 55% of the net primary productivity of the planet's terrestrial ecosystems ◦ Biologists estimate that the current global extinction rate of species is at least 100 times and probably 1000 to 10000 times what it was before humans existed ◦ Threats to biodiversity projected to increase sharply by 2018 ◦ The overall pattern is that global diversity is decreasing ▪ Naturally, ecosystems are dynamic and there is constant genetic change with new species being created and also going extinct Main Causes for Extinction and Decline of Biodiversity Globally • Natural causes of extinction include: ◦ Ecological processes such as competition and predation as well as diseases and more extreme events such as meteorites that alter the climate • Human activity: ◦ The increasing reliance on human systems on very narrow or low diversity levels of resources in fisheries, forestry, and agriculture ▪ As humans rely more on single crops or monocultures for subsistence, more species will be eliminated from the ecosystem ▪ In fisheries, it is the combination of overfishing with new forms of fishing such as aquaculture that is leading to a collapse of marine systems ◦ Population growth increases the demand for land which means less area available for natural and traditional land uses such as forests and wildlife habitat as well as cropland ◦ The government chooses to support less sustainable systems ▪ This means more subsidies to the development of traditional resources (forestry and agriculture) than to parks and ecotourism Types of Forests Related to Management (plantation, secondary) • Three major types of forests based on age and structure: ◦ Old-growth forest: an uncut forest or regenerated forest that has not been seriously disturbed by human activities or natural disasters for several hundred years ▪ They are storehouses of biodiversity because they provide ecological niches for a multitude of wildlife species ◦ Second-growth forest: a stand of trees resulting from secondary ecological succession ▪ They develop after trees in an area have been removed from
More Less

Related notes for ES102

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit