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SUMMARY ENGRCAP. 1- Engineering and the EnvironmentRole of engineering: Solve problems related to technology development and deployment  Design and build all the manufacturing processes, industrial technology and transportation infrastructure needed to extract, transport and refine raw materials, ...

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SUMMARY ENGR202 CAP. 1- Engineering and the Environment Role of engineering:  

Solve problems related to technology development and deployment Design and build all the manufacturing processes, industrial technology and transportation infrastructure needed to extract, transport and refine raw materials, fabricate products and distribute the goods and services

Green Engineering: Concepts of green design, industrial ecology and sustainable development differ from past approaches to engineering design in many ways Three major sources of environmental impacts that relate to what engineers design and build: Materials selection: The materials selection will affect the environment directly since everything that is designed has to be made out of something. So what has changed from past approaches to engineering is that now the engineers think about the choices of materials as well as the quantities needed for their design. For example, since the laws have changed due to environmental concerns, IBM was required to take back all their discarded computers that had toxic materials and therefore, after this, they decided that it was it was more economical to rethink the design and the materials used so that the manufacturing process didn’t include any toxic metals. Manufacturing processes: The manufacturing processes includes extracting the material, refining it, transporting it and transforming it into the final product. Each of these steps produces waste. Engineers and other workers from Dell, that was a computer technology company, committed to reduce the corporations total manufacturing emissions by 40% by the end of 2015, which is an example of a company that made changes in its manufacturing processes to reduce waste, in this case, air pollutants. Also, another example is Nike, which now has 60% less waste compared to traditional cut and sew shoe manufacturing, reducing its solid wastes. Energy use: The types and quantities of energy used for designs also contributes greatly to environmental quality. There are a lot of examples of companies that have changed their energy to a renewable energy source or that simply reduced the energy required for a particular service. For example, IKEA is investing in solar and wind energy and plans to hit 100% clean energy by 2020. Life cycle perspective: Past approaches from engineers led to focusing in small pieces of this overall system, which is made of the material extraction, processing, manufacturing, use and waste management. However, “Green” engineering knows that all parts of product’s life cycle have to be considered to reduce damages to the environment. Therefore, life cycle assessment is an important tool for

pollution prevention and waste management. It is composed of three steps: Goal and scope definition (define goal of assessment and boundaries of life cycles), analysis (identification and quantification of impacts) and assessment (assess environmental consequences of impacts determined in the analysis) Industrial ecology and sustainable development: Industrial ecology is the means with what humans can maintain a desirable carrying capacity, without hurting the environment. Industrial ecology should be reflected in engineering design and requires the industrial system to be viewed not in isolation from its surrounding systems. Sustainable development is a development that does not impair future generations. Basic engineering principles: Conservation of mass: Rate of creation of mass=0 (Total mass flow in) = (Total mass flow out) + (Change in mass stored) Conservation of energy: Rate of creation of energy=0 (Total energy flow in) = (Total energy flow out) + (Change in energy stored) (Fuel energy in) = (Electrical energy out) + (Heat to the environment) Industrial ecology approach: improve power plant design to reduce or utilize the waste heat released to the environment. Pure Science vs. Engineering: The difference is in the tools used. Pure science uses experiments and observation, while engineering uses mathematical models, to make predictions about the environmental impacts and to find solutions to environmental problems. Cap. 2: Overview of environmental issues Environmental impact: Affects humans and the environment (Death, severe illness, annoyance). Human welfare (effects of pollutants on plants, animals and materials) Human health effects: Acute: Exposure to pollutant causes an immediate response in the human body (shortness of breath) Chronic: Long term exposure to certain pollutants (chronic respiratory ailments) Carcinogenic: Pollutants initiate changes in cells that can lead to uncontrolled cell growth and division, know as cancer.

Air Pollution: 6 PRIMARY AIR POLLUTANTS: 

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Particular Matter (PM): small solid or liquid particles suspended in air, given off by fuel combustion, and most industrial and manufacturing processes and transportation sources. It causes respiratory and cardiovascular disease and potentially carcinogenesis and premature death. There was a dramatic reduction of particle emissions since the passage of the CLEAN AIR ACT (CAA). The predominant source is from dust from unpaved roads. Canada has standard PM10 (diameter 10 micros), wants to get to PM2.5. Sulfur Dioxide (SO2): Comes from combustion of coal and oil or metal smelting. Leads to respiratory illness, aggravation of cardiovascular disease. SO2 can also undergo chemical reactions that form gaseous sulfates that fall as acidic precipitation. Carbon Monoxide (CO): Colorless and odorless gas, that is produced when fossil fuels are not completely combusted. Causes shortness of breath and dizziness, as the body’s oxygen delivery system is choked off. Transportation technologies, mainly automobiles, are the dominant source of CO emissions. Nitrogen Dioxide (NO2): reddish-brown gas, that’s affects children, and in lower concentrations can irritate the respiratory system and produce respiratory illness and in high concentrations is toxic. It is a result from fuel combustion. Ozone: ground level ozone (bad ozone)- different from protective layer of the good ozone found in the stratosphere- is formed by chemical reactions (NOx (nitrogen oxides) with VOCs (Volatile organic compounds or ROGs reactive organic gases). It causes health problems related to the lungs, difficulty breathing and inflammation of airways and causes statues, fabrics to deteriorate and damages plants and trees. Lead: heavy metal that can cause neurological damage and adverse effects on organs (liver and kidney). Once ingested, it can bio accumulate in our organism. Can come from old lead pipes or lead paint that transport water or from gasoline that had lead in it (to make it last longer) or lead smelting and manufacturing processes.

Air toxics (Hazardous air pollutants HAPs): EPA (Environmental Protection Agency) releases an annual Toxics Release Inventory (TRI) that reports the emissions of toxic substances. Problems: 

Acid deposition (Acid rain): Any type of precipitation that is more acidic than normal (less than PH=7). The main chemicals in air pollution that create acid rain are sulfur dioxide (SO2) and nitrogen oxides (NOx). Acid rain usually forms high in the clouds where sulfur dioxide and nitrogen oxides react with water, oxygen, and oxidants. This mixture forms a mild solution of sulfuric acid and nitric acid. The SO2 can come from power plants hundreds of miles away- long distance transport of air pollutants. Acidification of lakes and streams affects the viability of fish and other aquatic organisms; contributes to the decline of some species of trees; disrupts the complex soil chemistry; and deteriorates buildings and monuments.

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Stratospheric Ozone Depletion: The good ozone layer in the stratosphere that prevents increased penetration of ultraviolet radiation is being depleted by human made chemicals, chlorofluorocarbons (CFCs). CFCs can enter the atmosphere and can reach the higher levels of the atmosphere. The UV radiation in the ozone layer can break CFC molecules and release chloride atoms, that destroys the ozone layer. Bromine is also an ozone-depleting-chemical introduced in the atmosphere by human beings. The Montreal Protocol phased out the use of CFCs. The numbers decreased, but it is necessary to find substitutes for the ozone-depleting-chemicals now in wide use. Greenhouse gases (GHGs): Compounds emitted to the atmosphere due to human activity that trap heat in the atmosphere (the same way that glass helps to trap solar energy in a greenhouse). CO2 contributes to 85% of global warming, Methane (CH4) (6-7%), and other secondary gases (many different gases, with different propertiesmakes the problem harder to solve). Global Warming Potential (GWP) turns Methane in CO2, NO2 in CO2, etc. to have an equivalent amount of CO2 to help with the calculations of the global warming potential. Effects and impacts: (1) Rising of sea level (2) Increased spread of tropical diseases (3) Increased precipitation and severity of storm events (frequency of modern tsunamis) (4) Climate change (5) Ecological effects as plants and animals attempt to cope with rapid changes

Water Pollution Sources and uses of water: 70% of the water comes from Surface waters (lakes, rivers and oceans) and 30% from groundwater (aquifers and springs). Biggest problem is that most of the surface water is salt water, not fresh water. Water is used for transportation, power production, recreation, drinking, cooking, manufacturing processes, construction and agricultural activities. Major water contaminants: 

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Pathogens: Bacteria, viruses, protozoa and parasitic worms that cause diseases. They can enter waterways from inadequately treated sewage discharges and drains, causing cholera, diarrhea, respiratory diseases, etc. Organic wastes: They are oxygen-depleting substances in surface waters and dissolved oxygen is the basic requirement for a healthy aquatic ecosystem. Biodegradable wastes are decomposed by bacteria that use dissolved oxygen to break down waste materials. When there is more organic waste than normal sustainable levels, there is bacteria growth and oxygen is depleted faster than it can be replenished by natural processes. The demand for oxygen by bacteria is called biological oxygen demand (BOD) and the demand by oxygendepleting substances is called chemical oxygen demand (COD), and high levels of BOD and COD indicate undesirable water quality. Nutrients: Nitrogen and phosphorus used widely in fertilizers and detergents are responsible for over enrichment of nutrients in lakes, rivers and streams, causing eutrophication, which means that the body of water supports an abundant growth of

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algae, that can eventually crowd out other forms of aquatic life. It also contributes to the depletion of oxygen, since bacteria feed on dead and decaying algae. Toxic organic chemicals: They can cause cancer (carcinogens), genetic mutations (mutagens) or impair bodily functions and damage vital organs. Oil spills are an example. Pesticides, such as DDT, is another example of toxic organic chemicals that are highly persistent in the environment: they tend to accumulate in the food chain. Also, VOCs can be found in industrial and household solvents and are suspected carcinogens that come from discharge of industries. Toxic metals: Mercury, lead and arsenic can damage vital organs or even kill, due to excessive levels from alteration due to human activity. Comes from smelting, industrial processes, runoff from mining and construction or from pipes, and enter surface waters. Also via atmospheric deposition, when volatized mercury can condense and settle on water and bio accumulate on fish high in the food chain. Mercury affects the nervous system. Sediments and suspended solids: Soil particles that settle at the bottom of the water body. A high level of total suspended solids (TSS) produces turbid water that blocks sunlight needed by aquatic vegetation. It comes from mining, construction, logging and farming (land erosion) and can be facilitated by removal of shoreline vegetation. Acidity: biological processes can be impaired in waters that are too acidic (PH

T e=[

S 0 ( 1−a ) 14 ] . σ

The flaw of this equation is that is does not account for the presence of certain gases in the earth’s atmosphere. Temperature and Radiative Spectrum: Equivalent wavelength earth (Infrared- IR) > wavelength from the sun (Ultraviolet (UV)) Above 3

μ m > below 3um

Black body of sun (T)>Black body from the earth Radiative properties of the atmosphere: H2O and CO2 capture most of the outgoing surface radiation, but there is a small region, called atmospheric window, where relatively little absorption occurs. It’s the region between 8um and 12um, where radiation passes directly through the atmosphere to space. Although ozone has a strong absorption band in the middle of this interval, because of its low concentration the overall effect is less pronounced. Earth Energy Balance Revisited: Actual Radiative Balance: A more accurate accounting of the global energy balance is shown by Intergovernmental Panel on Climate Change (IPCC), a group of scientists convened by the World Meteorological Organization

WMO) and the United Nations Environmental Program (UNEP) to access the problem of global climate change. Radiative forcing on climate change: More greenhouse gases result in more outgoing radiation to space being absorbed by those gases, resulting in a net decrease of outgoing radiation (DELTAQout). Any change in the average net radiation at the tropopause is referred to as radiative forcing (DELTAF). The term ‘forcing’ is used because any change in the net radiative balance will force the climate system to re-adjust itself to reach equilibrium, hence a change in climate due to greenhouse gas! This means that radiative forcing is a key factor determining how much the climate will change in response to disturbances of the earth’s energy balance induced by changes in greenhouse gas concentrations, aerosols, the earth’s albedo, and solar input. Models of radiative forcing: DELTAF=DELTAqout- If Qinnet cooling-green house gases decrease DELTAF-DELTAqin- If Qin>Qout-> net warming- green house gases increase Net forcing from atmospheric changes: DELTAF=DELTAqout - DELTAqin Radiative forcing versus Concentration: The initial concentration of a greenhouse gas strongly affects the magnitude of radiative forcing caused by increment in concentration.  

Low concentration regime: the radiative forcing increases in proportion to the number of molecules(C) DELTAF=A(C-Co)- linear- CFCs and halocarbons Moderate Concentration Regime: The molecules already absorbed much of the radiation where the wavelengths where absorption bands are strongest. The further absorption occurs at off-peak wave-lengths, where the absorption is lower, less energy absorbed, less radiative forcing from each new increment in concentration.

∆ F=B( √ C−√ Co) 

High concentrate Regime: further increases in concentration produce much smaller increases in radiative forcing- CO2

Co ln C−ln ¿ ∆ F=k ¿

Radiative forcing in the industrial age: Direct forcing from greenhouse gases: CO2 has the greatest contribution Indirect Forcing from greenhouse gases:

The direct emissions can produce changes in the atmosphere that also affect the earth’s radiative balance. Examples: VOCs and Nitrogen oxides (NOx) reacts in the troposphere to produce ozone and once formed the ozone adds to the radiative forcing. Also, the good layer of ozone is destroyed by direct emissions of CFCs, meaning more of outgoing radiation escapes to space, producing cooling, resulting in negative radiative forcing. Direct Forcing from aerosols: 

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Sulfate particles arise from the combustion of fossil fuels. These particles can reflect incoming solar radiation back out, resulting in higher albedo and negative radiative forcing and cooling. Aerosol particles from the combustion of biomass exhibit similar behaviour- negative radiative forcing Soot particles from fossil fuel combustion that absorb solar radiation that would otherwise be reflected, positive radiative forcing.

Indirect Forcing from aerosols: Aerosol particles can act in cloud formation, that reflect additional incoming radiation- cooling. Forcing due to solar radiation: Solar input is believed to have increased, producing net positive. Overall Radiative effect: Overall positive increase in radiative forcing= net warming effect Temperature changes from radiative forcing: Climate sensitivity factor:

γ =∆Te /∆ Frad

Ratio of the final temperature change to the change in radiative forcing Time lags and temperature commitment

∆ t lag =teq −t Where Tlag is the time it takes for a certain time in substance to reach the equilibrium temperature Teq. The difference between the equilibrium temperature and actual temperature = ΔT commitment Atmospheric Lifetime of Greenhouse Gases: −t

So we get m =m e τ 0

m 0 is the initial mass and τ is the atmospheric lifetime, the longer it is, the slower and more gradual the depletion. The average concentration of a substance in the atmosphere follows the same declining curve because the volume of any gas is proportional to its mass. For carbon there is a different equation:

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(

mc −t −t =0.375 exp +0.625 exp mc , o 10.43 291.5

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CO2 Emissions and Energy Use Most of the energy used throughout the world is in the form of fossil fuels consisting of oil, coal, and natural gas. Approx. 85% of US energy is supplied by fossil fuels, predominantly oil (petroleum products), for the world its 75% of the world’s energy consumption is by fossil fuels. In the US the energy consumption is divided like this: 38.5% Petroleum; 24.0% Natural Gas; 22.8% Coal; 7.6% Renewables; 7.1% Nuclear These energies are mainly used for the following: 34.6% electric utilities (including 1/3 goes to industry, 2/3 goes to residential & companies); 26.4% industry; 26.3% transportation; 12.6% residential and commercial Carbon content of Fuels To determine the total mass of CO2 emitted each year, we must know the amount of each fossil fuel consumed and the mass fraction of carbon content of fossil fuels. Mass of carbon emitted = (wt%C/ 100) *mass of fuel burned Energy Content of Fuels The energy delivered by a fossil fuel is determined mainly by its content of carbon and hydrogen, which release chemical energy when the fuel is burned. The quantity of energy per unit of fuel mass is known as the heating value and is typically expressed in units of kj/kg or kj/mol. Carbon Intensity of Fuels Basically its Carbon intensity = fuel carbon mass/ fuel energy Or carbon intensity = fraction of C in fuel / fuel heating value Reducing greenhouse affects: Factors affecting CO2 Emissions Growth: CO2 emissions= population X GDP (gross domestic product) X Energy use X Carbon intensity CO2 emissions/ per year = population/ per year * gdp / per capita *energy use/ per GDP * CO2 Emissions/per unit energy Population Growth: Increasing population generates greater demand for food, clothing, shelter, and other human needs. Meeting these increased demands results in additional greenhouse gas emissions from the use of energy and other activities.

GDP per Capita: As this grows, an individuals’ demand for goods and services such as improved education, improved health care, and more consumer products also grows. So if standard of living increases, then the potential of emitting greenhouse gases increases too. Energy Intensity: Basically it is the ratio of energy consumption to GDP, therefore it’s not surprising to see Russia and China up top and Japan at the bottom. You can say energy intensity is how much energy you use per dollar. Russia uses 11x more energy per dollar when compared to Japan. Carb...