AP Environmental cheat sheet, Study notes of Environmental science

Download AP Environmental cheat sheet and more Study notes Environmental science in PDF only on Docsity! Page 1 of 58 Return to Table of Contents AP Environmental Science “Cheat” Sheet Table of Contents Unit 1—Pages 2-7 Unit 2—Pages 8-17 Unit 3—Pages 18-20 Unit 4—Pages 21-24 Unit 5—Pages 25-31 Unit 6—Pages 32-51 Unit 7—Pages 52-54 Page 2 of 58 Return to Table of Contents Unit 1 Ecosystems Big Ideas 1.1 Introduction to Ecosystems 1. Predator-prey relationship Predator: organism that eats another organism Prey: organism eaten by prey 2. Symbiotic Relationships Symbiosis: relationship between two species in an ecosystem Types (1) Mutualism - both benefit (2) Commensalism - one benefits/other isn’t affected (3) Parasitism - one benefits (parasite)/other is harmed (host) 3. Competition -occurs when resources are limited -reduced by Resource Partitioning Page 3 of 58 Return to Table of Contents 1.2 Terrestrial Biomes 1. Biome -area with characteristic plants & animals -defined by climate (temperature & precipitation) -is a Limiting Factor in ecosystems (because it is scarce) 1.7 Hydrologic (Water) Cycle Reservoirs: oceans, ice caps, groundwater Page 6 of 58 Return to Table of Contents 1.8 Primary Productivity -rate at which solar energy (sunlight) is converted into organic compounds through Photosynthesis GPP (Gross Primary Productivity) -TOTAL rate of photosynthesis in an area NPP (Net Primary Productivity) NPP = GPP - Respiration 1.9 Trophic Levels 1.10 Energy Flow & 10% Rule 1st Law of Thermodynamics - total amount of energy stays the same 2nd Law of Thermodynamics - as energy changes from one form to another, some is lost as heat Page 7 of 58 Return to Table of Contents 1.11 Food Chains & Food Webs Food Chain Food Web Feedback loops compared Page 8 of 58 Return to Table of Contents Unit (# 2)--The Living World: Biodiversity Biodiversity Outline I. Levels of Diversity A. species diversity (biodiversity) B. Ecosystem diversity C. Genetic diversity II. Benefits of Biodiversity A. species are connected to ecosystems B. for species and population survival C. medical, industrial, and agricultural uses D. ethics, aesthetics, and recreation III. Species at risk A. small populations in limited areas B. those that migrate C. those that need large or special habitats D. exploited by humans IV. How humans affect biodiversity A. H – Habitat Destruction/Alteration/Fragmentation B. I – Invasive/exotic/alien species C. P – Pollution D. P – Human population growth E. C – Climate Change F. O – Overexploitation – harvesting, hunting, poaching G. Disease - can sometimes be caused/spread by us V. Areas of critical biodiversity A. Tropical Rain Forests B. Coral Reefs & Coastal Ecosystems C. Islands VI. Ways to protect biodiversity A. Captive-breeding programs B. Preserving genetic material (germ-plasm banks) C. Zoos, Aquariums, Parks, Botanical Gardens D. Education E. Preserving habitats and ecosystems (BEST METHOD) • Page 10 of 58 Return to Table of Contents • The more genetically diverse a population is, the better it can respond to environmental stressors. Additionally, a population bottleneck can lead to a loss of genetic diversity. • Ecosystems that have a larger number of species are more likely to recover from disruptions. • Loss of habitat leads to a loss of specialist species, followed by a loss of generalist species. It also leads to reduced numbers of species that have large territorial requirements. • Species richness refers to the number of different species found in an ecosystem. • • Page 11 of 58 Return to Table of Contents • • Regionally extinct - In areas a species is normally found Functionally extinct - To the point at which species can no longer play a functional role in the ecosystem Page 12 of 58 Return to Table of Contents • •Many island species have evolved to be specialists versus generalists because of the limited resources, such as food and territory, on most islands. The long-term survival of specialists may be jeopardized if and when invasive species, typically generalists, are introduced and outcompete the specialists. 2.4 Ecological Tolerance • Ecological tolerance refers to the range of conditions, such as temperature, salinity, flow rate, and sunlight that an organism can endure before injury or death results. Ecological tolerance can apply to individuals and to species. • 2.5 Natural Disruptions to Ecosystems •Natural disruptions to ecosystems have environmental consequences that may, for a given occurrence, be as great as, or greater than, many human-made disruptions. Page 15 of 58 Return to Table of Contents • Earth system processes operate on a range of scales in terms of time. Processes can be periodic, episodic, or random. Page 16 of 58 Return to Table of Contents • Earth’s climate has changed over geological time for many reasons. • Sea level has varied significantly as a result of changes in the amount of glacial ice on Earth over geological time. •Major environmental change or upheaval commonly results in large swathes of habitat changes. •Wildlife engages in both short- and long-term migration for a variety of reasons, including natural disruptions. 2.6 Adaptations •Organisms adapt to their environment over time, both in short- and long-term scales, via incremental changes at the genetic level. • Environmental changes, either sudden or gradual, may threaten a species’ survival, requiring individuals to alter behaviors, move, or perish. Page 17 of 58 Return to Table of Contents 2.7 Ecological Succession • There are two main types of ecological succession: primary and secondary succession. • • Density-dependent factors have a greater effect on the population as its density increases. (ex. food availability, parasites, diseases) • A limiting resource is a resource that a population cannot live without and which occurs in quantities lower than the population would require to increase in size. • Density-independent factors affect a population’s size regardless of its density. (ex. natural disasters) 3.6 Age Structure Diagrams • Age structure diagrams are visual aids that show the distribution of males and females in each age group. • If a country has more young people than old people, its age structure diagram will be wider at the bottom, this is called a population pyramid. • Countries with little difference between the numbers of individuals in different age groups looks more like a column. • A country with more older than younger people has a diagram that resembles an inverted pyramid. Page 20 of 58 Return to Table of Contents 3.7 Total Fertility Rate • Total fertility rate (TFR) is an estimated of the average number of children that each woman in a population will bear throughout her reproductive years. (2.1 in the US) • Replacement-level fertility is the TFR required to offset the average number of deaths in a population so that the current population size remains stable. • Infant mortality rate is the number of babies out of every 1,000 born who die before their first birthday; availability of prenatal care is an important predictor of infant mortality. 3.8 Human Population Dynamics • In 1798 Thomas Malthus noticed that the human population was growing exponentially while the food supply was only growing linearly; he concluded that the human population would eventually exceed its food supply. • Doubling time is the number of years it takes for a population to double, assuming the growth rate is constant.; doubling time (in years) = 70/growth rate 3.9 Demographic Transition • The theory of demographic transition states that as a country moves from a subsistence economy to industrialization and increased affluence, it undergoesa predictable shift in population. • Phase One: preindustrial; early steady state (high birth & death rates); short life expectancy, high infant mortality rate; subsistence economy • Phase Two: transitional; death rates decline while birth rates remain high (large TFR); better sanitation, clean drinking water, increased access to food, goods & health care (vaccines) • Phase Three: industrial; birth rate & death rates decrease (return to steady state); economy & educational system improve, income increases • Phase Four: postindustrial; declining population, higher proportion of elderly people; pension programs and social security strained; people need to immigrate in to care for elderly Page 21 of 58 Return to Table of Contents Unit 4: Earth Systems and Resources 4.1 Plate Tectonics • Earth’s structure o Lithosphere o Mantle o Core • 3 Plate Boundary Types o Convergent o Divergent o Transform • Subduction Zones • Earthquakes (Richter scale) • Volcanoes 4.2 Soil Formation & Erosion • Weathering (biological, chemical, physical) • Transportation • Erosion • Deposition • Soil Horizons o O o A o E o B o C o R Page 22 of 58 Return to Table of Contents 4.3 Soil Composition & Properties • Water Holding Capacity • Porosity (pore space) • Permeability (rate of water flow) • Soil Testing o Nutrients (N, P, K) o pH moderating effect of large bodies of water • Land heats/cools faster than oceans • Rainshadow Effect 4.9 El Nino & La Nina • Pacific Ocean • Normal/Neutral o Winds blow E-W o Upwelling in S. America o Warm & wet in Asia • El Nino o Winds weaken or stop o Upwelling stops o Warm & wet in S. America • La Nina o “extreme” normal Page 25 of 58 Return to Table of Contents Unit 5--Land & Water Use 5.1 The Tragedy of the Commons -individuals use shared resources selfishly resulting in depleted resources 5.2 Clearcutting -removal of all trees from an area Advantage: more land for crops/animals leading to economic benefit Disadvantages: increases soil erosion, soil & stream temps., flooding, atmospheric CO2 5.3 The Green Revolution -use of mechanization, GMOs, fertilization, irrigation, pesticides to INCREASE food production Advantage: increases profits & efficiency Disadvantage: increased use of fossil fuels 5.4 Impact of Agricultural Practices -practices include tilling, slash-and-burn farming, use of fertilizers -causes eutrophication, soil degradation, habitat destruction, erosion Page 26 of 58 Return to Table of Contents 5.5 Irrigation Methods -70% of freshwater used for irrigation -excess irrigation leads to Waterlogging - excess water in soil, raises water table, inhibits plant root absorption of O2 Types 1) Furrow irrigation: furrows flooded between crop rows -inexpensive -low efficiency (approx. 50% water loss) 2) Flood irrigation: flooding field -low efficiency (approx. 20% water loss) -leads to waterlogging 3) Spray irrigation: spray water across field from sprinkler system -low efficiency (approx. 25% water loss) -expensive -requires energy to run (fossil fuels) 4) Drip irrigation: water released through perforated hoses at plant roots -higher efficiency (approx. 5% water loss) -expensive Salinization: salts in groundwater remain in soil after water evaporates causing soil to become toxic to plants Aquifers: underground freshwater reservoirs -depleted due to overuse for agricultural irrigation EX: Ogallala Aquifer 5.6 .6 Pest Control Methods Common methods include: pesticides, herbicides, fungicides, rodenticides, insecticides -leads to Resistance -decreases crop damage -increases crop yields Page 27 of 58 Return to Table of Contents 5.12 Introduction to Sustainability Sustainability: using resources in ways that don’t deplete amounts available for future use Sustainable yield: amount of a renewable resource that can be taken without reducing available supply Page 30 of 58 Return to Table of Contents 5.13 5.14 Methods to Reduce Urban Runoff Increase water infiltration by: 1) use permeable pavement 2) plant trees 3) use public transportation 4) build vertically Integrated Pest Management -pest control methods that minimize environmental damage -reduces pesticide use -complex and expensive Include: 1) biocontrol 2) intercropping 3) crop rotation 4) natural predators 5.1 Sustainable Agriculture Soil conservation methods 1) contour plowing 2) windbreaks 3) perennial crops 4) terracing 5) no-till 6) strip cropping 7) crop rotation Page 31 of 58 Return to Table of Contents 8) rotational grazing 5.16 Aquaculture -fish and aquatic plants farming Advantages: efficient, uses small areas of water & amounts of fuel Disadvantages: contamination from wastes, escapees competing/breeding with wild fish (decreases biodiversity, introduces diseases into wild population 5.17 Sustainable Forestry Ways to decrease Deforestation 1) reforestation 2) use ecologically sustainable wood 3) reuse wood Reduction of Pests 1) Integrated Pest Management 2) removal of infected trees Prescribed burns: controlled fires in forests to reduce occurrence of natural fires Page 32 of 58 Return to Table of Contents Unit 6--Energy Resources & Consumption ● Important Concepts to Know: Fossil Fuels, Nuclear Fuel, Nonrenewable vs. Renewable Resources, Turbine, Electrical Grid, Energy Carrier, Cogeneration, Capacity, Combined Cycle, Commercial vs. Subsistence Energy Source, Energy Efficiency 6.1 Renewable and Nonrenewable Energy Sources ● Nonrenewable energy sources are those that exist in a fixed amount and involve energy transformation that cannot be easily replaced. ● Renewable energy sources are those that can be replenished naturally, at or near the rate of consumption, and reused. 6.2 Global Energy Consumption ● The use of energy resources is not evenly distributed between developed and developing countries. ● The most widely used sources of energy globally are fossil fuels. ● As developing countries become more developed, their reliance on fossil fuels for energy increases. ● As the world becomes more industrialized, the demand for energy increases. ● Availability, price, and governmental regulations influence which energy sources people use and how they use them. 6.3 Fuel Types and Uses ● Wood is commonly used as fuel in the forms of firewood and charcoal. It is often used in developing countries because it is easily accessible. ● Peat is partially decomposed organic material that can be burned for fuel. ● Three types of coal used for fuel are lignite, bituminous, and anthracite. Heat, pressure, and depth of burial contribute to the development of various coal types and their qualities. ● Natural gas, the cleanest of the fossil fuels, is mostly methane. ● Crude oil can be recovered from tar sands, which are a combination of clay, sand, water, and bitumen. ● Fossil fuels can be made into specific fuel types for specialized uses (e.g., in motor vehicles). ● Cogeneration occurs when a fuel source is used to generate both useful heat and electricity. 6.4 Distribution of Natural Energy Resources ● The global distribution of natural energy resources, such as ores, coal, crude oil, and gas, is not uniform and depends on regions’ geologic history. Page 33 of 58 Return to Table of Contents 6.13 Energy Conservation ● Some of the methods for conserving energy around a home include adjusting the ● Crude oil can be recovered from tar sands, which are a combination of clay, sand, water, and bitumen. ● Fossil fuels can be made into specific fuel types for specialized uses (e.g., in motor vehicles). ● Cogeneration occurs when a fuel source is used to generate both useful heat and electricity. 6.5 Fossil Fuels ● The combustion of fossil fuels is a chemical reaction between the fuel and oxygen that yields carbon dioxide and water and releases energy. ● Energy from fossil fuels is produced by burning those fuels to generate heat, which then turns water into steam. That steam turns a turbine, which generates electricity.● Humans use a variety of methods to extract fossil fuels from the earth for energy generation. ● Hydrologic fracturing (fracking) can cause groundwater contamination and the release of volatile organic compounds. 7.1 Introduction to Air Pollution Coal combustion releases air pollutants including carbon dioxide, sulfur dioxide, toxic metals, and particulates. ● The combustion of fossil fuels releases nitrogen oxides into the atmosphere. They lead to the production of ozone, formation of photochemical smog, and convert to nitric acid in the atmosphere, causing acid rain. Other pollutants produced by fossil fuel combustion include carbon monoxide, hydrocarbons, and particulate matter. ● Air quality can be affected through the release of sulfur dioxide during the burning of fossil fuels, mainly diesel fuels. ● Through the Clean Air Act, the Environmental Protection Agency (EPA) regulated the use of lead, particularly in fuels, which dramatically decreased the amount of lead in the atmosphere. ● Air pollutants can be primary or secondary pollutants. 9.4 Increases in Greenhouse Gases (Modules 2, 7, 12, 35, 38, 46, 62, 63) ● Global climate change, caused by excess greenhouse gases in the atmosphere, can lead to a variety of environmental problems including rising sea levels resulting from melting ice sheets and ocean water expansion, and disease vectors spreading from the tropics toward the poles. These problems can lead to changes in population dynamics and population movements in response. Page 36 of 58 Return to Table of Contents Fossil Fuel Formation The formation of fossil fuels requires the burial and compression of organic materials under anaerobic conditions → prevents decomposition. Three Types of Fossil Fuels: • Coal (solid), Oil/Petroleum (liquid), Natural gas (gas), Terrestrial life → coal Aquatic life → oil/natural gas Fossil Fuel Formation: ● Coal vs. Oil and Natural Gas Three primary types of coal: • Lignite (lowest energy and lowest %carbon) • Bituminous (US has the most, but high sulfur content) • Anthracite (highest energy and most %carbon) • More carbon = fewer impurities, cleaner Page 37 of 58 Return to Table of Contents Peat is a precursor to coal and is composed of partially decomposed organic matter, Coal requires mining, usually strip mining Coal Formation When vegetation is rapidly buried and compressed it forms peat → lignite → coal Peat: soil-like material consisting of partly decomposed vegetable matter. Lignite: a soft brownish coal showing traces of plant structure, intermediate between bituminous coal and peat. Coal: a combustible rock consisting mainly of carbonized plant matter, found mainly in underground deposits and widely used as fuel. ● Coal Reserves Top 5: US, Russia, China, India, Australia Coal Advantages and Disadvantages Advantages: Cheap, plentiful, easily mined Disadvantages: Combustion of coal produces CO2,Very dirty- lots of impurities like sulfur → acid rain and other ecological effects, Produces lots of ash as waste Natural gas is recovered through wells. These are generally drilled into shale rock. In what kind of rock is natural gas found? Defend your answer. ● Natural Gas Advantages and Disadvantages Advantages: Great for heating (cogeneration), Cleaner than oil or coal (fewer impurities), Less CO2 released than other fossil fuels Disadvantages: Methane (primary component of natural gas) is a terrible greenhouse gas, Exploration is disruptive (thumper trucks), Extraction is damaging (fracking) Nuclear Energy Resources Important Concepts to Know: Nuclear Fission, Fuel Rods, Control Rods, Radioactive Waste, Nuclear Accidents, Nuclear Fusion, Advantages and Disadvantages to Nuclear Power 6.4 Distribution of Natural Energy Resources ● The global distribution of natural energy resources, such as ores, coal, crude oil, and gas, is not uniform and depends on regions’ geologic history. 6.5 Fossil Fuels ● The combustion of fossil fuels is a chemical reaction between the fuel and oxygen that yields carbon dioxide and water and releases energy. ● Energy from fossil fuels is produced by burning those fuels to generate heat, which then turns water into steam. That steam turns a turbine, which generates electricity. ● Humans use a variety of methods to extract fossil fuels from the earth for energy generation. ● Hydrologic fracturing (fracking) can cause groundwater contamination and the release of volatile organic compounds. 6.6 Nuclear Power ● Nuclear power is generated through fission, where atoms of Uranium-235, which are stored in fuel rods, are split into smaller parts after being struck by a neutron. Nuclear fission releases a large amount of heat, which is used to generate steam, which powers a turbine and generates electricity. Page 41 of 58 Return to Table of Contents ● Radioactivity occurs when the nucleus of a radioactive isotope loses energy by emitting radiation. ● Uranium-235 remains radioactive for a long time, which leads to the problems associated with the disposal of nuclear waste. ● Nuclear power generation is a nonrenewable energy source. Nuclear power is considered a cleaner energy source because it does not produce air pollutants, but it does release thermal pollution and hazardous solid waste. ● Three Mile Island, Chernobyl, and Fukushima are three cases where accidents or natural disasters led to the release of radiation. These releases have had short- and long-term impacts on the environment. ● A radioactive element’s half-life can be used to calculate a variety of things, including the rate of decay and the radioactivity level at specific points in time. Nuclear Power Developed from nuclear weapons technology Originally deemed risky/expensive compared to fossil fuels. But interested peaked in 1970s with the gas crisis, Accidents limited public interest ● Light Water Nuclear Reactors Cheaper than other types of reactors though not as effective (1% efficiency) Fuel source = U-235 Neutrons bombard the Uranium causing fission and the release of energy which is used to heat up the water. This produces steam which can be used by a turbine to produce electricity. Water moderates the reaction, keeping it controlled. Failure to do so results in a meltdown (not unlike a nuclear bomb) Not the safest, most efficient or most advanced type of nuclear reactor ● Disadvantages to Nuclear Energy 1. Nuclear Weapons Proliferation • Nuclear reactor technology is intimately tied to nuclear weapons technology. 2. Nuclear Waste • Radioactive and long-lived (long half life) • Secure storage is difficult • Security for transportation of waste to storage 3. Nuclear Accidents • Three-Mile Island (1979) • Chernobyl (1986) • Fukushima (2011) ● Advantages to Nuclear Energy Page 42 of 58 Return to Table of Contents ● 1. Nuclear Energy Saves Lives • Produces fewer pollutants and the pollutants (radioactive waste) is more regulated and stored 2. Nuclear Energy reduces CO2 emissions • Nuclear reactions are not a combustion reaction → no CO2 produced 3. New Technologies (Fast Reactors) • Light Water Reactors are out of date • Breeder reactors can use Thorium which is not used in nuclear weapons● Types of Radioactive Waste Low-Level ● Low-level waste (LLW) is generated from hospitals and industry ● Low radioactivity level and short half life ● Makes up 90% of the bulk of radioactive waste, but only 1% of the radioactivity.● No shielding is required, ideal for shallow burial. High-Level ● High-level waste (HLW) is generated from the use of uranium in light water nuclear reactors. ● High radioactivity and long half life (tens of thousands of years compared to hundreds of years for LLW) ● Requires cooling and shielding. Dealing with nuclear wastes • Shallow burial • Deep geological burial • Yucca Mountain (2010) • Vitrification Page 43 of 58 Return to Table of Contents Energy Reduction Humans use 17.7 TW (terrawatts) of electricity Conservation and efficiency will help reduce our overall energy demands Reducing Energy Demands Peak Demand occurs during the day. To reduce energy consumption, electric companies charge higher rates as customers use more energy or charge more during peak demand. Conservation and Efficiency both feed into reducing energy needs. Sustainable Designs Sustainable design helps to, use passive heating heat and solar designs. The fact that the design is passive means that we do not need to input as much energy into the upkeep of the building; takes advantage of natural processes Green Roofs CAFE Standards Plants are grown on the roof of a building The high albedo of the plants absorbs sunlight, keeping the buildings cool The plants also take up water, reducing rainwater flow Page 46 of 58 Return to Table of Contents CAFE Standards Enacted in the US in 1975 in response to the OPEC oil crisis (73-74) Focused on efficiency of automobiles, raising standards → less dependence on oil and greater economic security. Hybrids and electric vehicles help bridge the gap Biomass and Water. Important Concepts to Know: Biofuel, Ethanol, Biodiesel, Modern vs. Fossil Carbon, Carbon Neutral, Net Removal, Flex-Fuel Vehicle, Hydroelectricity, Run-of-the River, Water Impoundment, Tidal Energy, Siltation 6.7 Energy from Biomass ● Burning of biomass produces heat for energy at a relatively low cost, but it also produces carbon dioxide, carbon monoxide, nitrogen oxides, particulates, and volatile organic compounds. The overharvesting of trees for fuel also causes deforestation. ● Ethanol can be used as a substitute for gasoline. Burning ethanol does not introduce additional carbon into the atmosphere via combustion, but the energy return on energy investment for ethanol is low. 6.9 Hydroelectric Power Hydroelectric power can be generated in several ways. Dams built across rivers collect water in reservoirs. The moving water can be used to spin a turbine. Turbines can also be placed in small rivers, where the flowing water spins the turbine. ● Tidal energy uses the energy produced by tidal flows to turn a turbine.● Hydroelectric power does not generate air pollution or waste, but construction of the power plants can be expensive, and there may be a loss of or change in habitats following the construction of dams. 9.4 Increases in Greenhouse Gases ● Global climate change, caused by excess greenhouse gases in the atmosphere, can lead to a variety of environmental problems including rising sea levels resulting from melting ice sheets and ocean water expansion, and disease vectors spreading from the tropics toward the poles. These problems can lead to changes in population dynamics and population movements in response. Biomass Biomass refers to energy derived from living organisms→ biomass fuel sources are derived from living tissues generally plants. Wood and charcoal are types of biomass energy as is biofuel Combustion is the primary way of extracting energy from biomass Biofuel Biofuels are liquid fuels similar to petroleum but derived from biomass Ethanol and biodiesel are examples. Ethanol can be used directly or as an additive to gas (gasohol), effectively increasing our petroleum supplies. Biodiesel can be used in a similar manner but with diesel. How are gas and diesel different? Ethanol Page 47 of 58 Return to Table of Contents Typically derived from corn Ethanol + gas → gasohol (90% gas and 10% ethanol) E85 is 85% ethanol and 15% gas and can be used in flex fuel vehicles along with traditional gas Because ethanol is renewable it extends of reserves of petroleum ● The downsides to ethanol Derived from cellulose and other plant tissues- that must be broken down into simpler sugars. Requires processing with enzymes Ethanol comes primarily from corn so we are using food to make fuel. Corn is the foundation of most of our food infrastructure, prices will go up universally Switchgrass may be an alternative to corn, but still requires land to grow again competing for space with our food. Plus growing these plant requires...fossil fuels. So are we actually conserving our resources? Hydroelectric Power Converts kinetic energy → electrical energy 7% of renewable energy comes from hydropower largest source of renewable energy Impoundment systems capture water and divert water flow Solar, Wind, Geothermal and Hydrogen. Important Concepts to Know: Active Solar Design, Photovoltaic Cell, Wind Energy, Wind Turbine, Geothermal Energy, Ground Source Heat Pump, Fuel Cell, Electrolysis 6.8 Solar Energy ● Photovoltaic solar cells capture light energy from the sun and transform it directly into electrical energy. Their use is limited by the availability of sunlight. ● Active solar energy systems use solar energy to heat a liquid through mechanical and electric equipment to collect and store the energy captured from the sun. ● Passive solar energy systems absorb heat directly from the sun without the use of mechanical and electric equipment, and energy cannot be collected or stored. Page 48 of 58 Return to Table of Contents ● Solar energy systems have low environmental impact and produce clean energy, but oxygen and hydrogen gas. Advantages: hydrogen gas contains lots of energy (3x compared to gas); no CO2 from combustion Disadvantages: requires lots of energy to produce, highly flammable Photosynthesis and Hydrogenase Genetic modification??? Planning Our Energy Future ● Important Concepts to Know: Smart Grid, Efficiency, Conservation and the Development of Renewable and Nonrenewable Energy Resources, Renewable Energy Present Challenges, Table 40.1: Comparison of Renewable Energy Resources 6.1 Renewable and Nonrenewable Energy Sources ● Nonrenewable energy sources are those that exist in a fixed amount and involve energy transformation that cannot be easily replaced. ● Renewable energy sources are those that can be replenished naturally, at or near the rate of consumption, and reused. 6.13 Energy Conservation Page 51 of 58 Return to Table of Contents Some of the methods for conserving energy around a home include adjusting the thermostat to reduce the use of heat and air conditioning, conserving water, use of energy-efficient appliances, and conservation landscaping. ● Methods for conserving energy on a large scale include improving fuel economy for vehicles, using BEVs (battery electric vehicles) and hybrid vehicles, using public transportation, and implementing green building design features. We Need a Smart Grid Our current electrical grid is out of date and wasteful. As we expand our energy economy to include renewable energy, electricity will need to be moved between locations more often. A self-regulating, more efficient smart grid will better regulate this exchange and prevent blackouts and burnouts. Smart Grid Switching to renewable energies means diversification. A smart grid will better coordinate our power consumption. Needs to be able to utilize all sources of electricity, renewable and nonrenewable● Energy Storage Wind, solar and tidal energy are renewable and have the smallest environmental impact, but they represent a “boom or bust” economy- energy is not always available. To make this more efficient and useful, we need to capitalize on opportunities when energy is available and store energy for later use. Improving our efficiency and storage will ultimately translate to cheaper electricity as supply increases. Page 52 of 58 Return to Table of Contents Unit 7: Atmospheric Pollution 7.1 Introduction to Air Pollution • Air pollution is the introduction of chemicals, particulate matter, or microorganisms into the atmosphere at concentrations high enough to harm plants, animals, and materials such as buildings, or to alter ecosystems • Ground-level pollution occurs in the troposphere (bottom layer of the atmosphere), which is what we generally mean when we refer to airpollution • The Clean Air Act (1970) identified the following as significant threats to human well-being, ecosystems, and structures (VOCs, CO2, and Hg are being considered for the list) • Sulfur Dioxide: SO2 is a corrosive gas that comes primarily from combustion of fuels like coal and oil • Nitrogen Oxides: Generically described as NOx; NO is a colorless, odorless gas, NO2 is a pungent, reddish-brown gas • Carbon Oxides: CO is a colorless, odorless gas that is formed during incomplete combustion, CO2 is a colorless, odorless gas that is formed during complete combustion (of fossil fuels & biomass) 7.2 Photochemical Smog • Photochemical oxidants are formed as a result of sunlight acting on compounds such as NOx and SO2; Ozone is the most abundant photochemical oxidant in the troposphere • Smog (smoke + fog) is a mixture of oxidants and particulate matter; Photochemical smog, Los Angeles-type smog, brown smog is mostly composed of oxidants like ozone, Sulfurous smog, London-type smog, gray smog is mostly SO2, and sulfate compounds (from burning coal) • Mercury is also found in coal and oil, causes CNS damage; released primarily from the combustion of fossil fuels (especially coal), coal-fired power plants are the largest uncontrolled source • Volatile organic compounds (VOCs) are organic compounds that become vapors at typical atmospheric temperatures; many are hydrocarbons—gasoline, lighter fluid, dry-cleaning fluid, oil-based paints, perfumes • Primary pollutants come directly out of the smoke-stack, exhaust pipe, or natural emission source; include CO, CO2, SO2, NOx, VOCs • Secondary pollutants are primary pollutants that have undergone transformation in the presence of sunlight, H2O, O2, or other compounds; includes O3, H2SO4, HNO3 • On-road vehicles (transportation) are the largest source of CO and NOx • Electricity production by coal is the largest producer of SO2 Page 53 of 58 Return to Table of Contents 7.3 Thermal Inversion • A thermal inversion occurs when a relatively warm layer of air at mid-altitude covers a layer of cold, dense air below 7.4 Atmospheric CO2 and Particulates • CO2 is a colorless, odorless gas that is formed during complete combustion (of fossil fuels & biomass) • Particulate matter (PM), particulates, particles can be solids or liquids suspended in the air; comes from the combustion of wood, animal manure, fossil fuels (especially coal and oil), biofuels 7.5 Indoor Air Pollutants • Asbestos is a long, thin, fibrous silicate mineral with insulating properties • People who mined asbestos have high rates of asbestosis (scarring of the lungs caused by inhaled fibers) and lung cancer • Radon-222 is a naturally occurring radioactive gas that is produced by the decay of uranium. It can seep into homes through cracks in the foundation, or soil, or drinking water. • Buildings that are more tightly sealed and insulated allow toxic compounds and pollutants to build up in the airtight space; indoor levels of VOCs, hydrocarbons, and other compounds can be quite high in these buildings 7.6 Reduction of Air Pollutants