Lecture Topic # 5 Energy Sources - Bridgewater State University

Lecture Topic # 5Energy SourcesPart 1: Fossil fuels(Chapters 7 & 8)A coal-fired power plant: Photo by Steev Hise (CC). Image available athttp://www.allamericanpatriots.com/news topics/greenhouse gases?page 31Fuels Used to Generate Electricity* Coal and oil - contain hydrocarbons; emit greenhouse gaseslike CO2 when burnedCombustion:CxHy O2Hydrocarbons in coal, oilCO2 H2O HeatGreenhouse gas* Natural gas, CH4 (methane) – also releases CO2Combustion:CH4 O2CO2 H2O HeatNuclear fuel, such as uranium and plutonium Radioactive decay produces heat* Coal, oil (petroleum) and natural gas are collectively called fossil fuels.They are nonrenewable energy sources.21

Energy Use and PollutionFrom Chapters 3-5:CombustionFossil fuelsAir pollutants, smog, acidrain, global warming, etc.Nonrenewableenergy sourcesSolution: Switch to renewable energy (e.g. solar, wind) andalternative fuel (e.g. H2) – will be discussed in thenext chapterGoal: To reduce air pollution3Nonrenewable EnergyDefinition: Nonrenewable energy sources are those thatcannot be replaced after we have used them upExample: Fossil fuels (coal, oil and natural gas) Created hundreds of millions of years ago whenancient plants and animals died and were buried inswamps, lakes and seabed42

Supply of Fossil Fuels Supplies of fossil fuels are limited. There is probably enough crude oil (petroleum) and gas to lastus until the mid-century - See graph Coal reserves may last for several centuries5Background: Generation of ElectricityImage available at day-5/63

Generation of Electricity – Cont.Most power plants are big boilers that burn a fuel to makeheat. In most boilers, wood, coal (hence the term coal-firedpower plant), oil or natural gas is burned to make heat. Thatheat energy is used to boil water to make steam. The steam isfed under high pressure to a turbine. The steam turbine hasmany blades that look like the blades of a fan. When thesteam hits the blades they spin a shaft that is attached to thebottom of the blades. The shaft is connected to a generatorthat changes the mechanical spinning energy into electricity.7Sources of electricity in the USA 2009. Data able1 1.html. Image available athttp://en.wikipedia.org/wiki/File:2008 US electricity generation by source v2.png84

National CO2 Emissions from Fossil Fuel-Burning PowerPlants as Measured by Acid Rain Program Continuous EmissionsMonitoring Systems (CEMS) ; http://www.epa.gov/captrade/maps/co2.html9Total U.S. Greenhouse Gas Emissionsby Economic Sector in 2010Electricity Transportation IndustryTotal Emissions in 2010 6,822 Million Metric Tons of CO2 equivalent* Land Use, Land-Use Change, and Forestry in the U.S. is a net sink and offsets approximately15% of these greenhouse gas emissionsImage available at ces.html105

11Total emissions of CO2 by country in 2007Percent of global CO2 emissions25%20%15%10%5%0%Source of data:http://en.wikipedia.org/wiki/List of countries by carbon dioxide emissions#cite note-7126

Fossil fuels: Coal Most abundant and cheapest of the fossil fuels 75 % of the world’s coal reserves comes from: U.S. Russia China India Australia Dirtiest; produces the most CO2 per joule of (electrical)energy produced13What else is in coal?CarbonSulfur(Impurity in coal, 1-6% S)The structure of coal Nitrogen HydrogenThus, burning of coal also releases sulfur dioxide (SO2), somenitrogen oxides (NOx) and naturally occurring elements likeHg, U and Pb as by-products.147

Fossil fuels: Petroleum (Crude Oil) Petroleum is a mixture of hydrocarbonsSource: fossil remains of microscopic marine animalsPetroleum (crude oil) flowing into temporary tanks. Image available page/news/2615Products of petroleum refining Oil refineries utilize the process of fractional distillation –to separate petroleum into its constituent hydrocarbons.(Image available at http://www.qedoc.org)Notes:168

Petroleum – Cont. Gasoline is a major fraction of petroleum refiningImage available at Petroleum – Cont. Right: A distillation column at the Richmond Refinery Photo of a petroleum refinery (below)Images available athttp://www1.eere.energy.gov/industry/petroleum refining/printable versions/profile.htmland n-renewable/refinery.html 189

Fossil Fuels: Natural GasNatural gas consists of short-chain alkanes Methane (CH4) is the principal componentof natural gas. Methane is transported through pipelines toconsumers Used for cooking, heating homes & buildings Combustion of methane:CH4 2 O2 CO2 2H2O heat19Where We Find Natural GasThe U.S. has a lot of natural gas,enough to last for at least another60 years.Canada, also has a lot of gas, andsome gas pipelines that begin inCanada run into the U.S.Image available sons/gas/2010

How Does Natural Gas Get To Our Homesand Businesses? A liquefied natural gas (LNG) tanker on its way to the Distrigasterminal in Everett, headed into Boston Harbor under the flight pathof Logan International Airport. (David L. Ryan/ Globe Staff)Image available rticles/2006/09/10/despitemillions spent boston is vulnerable/21How Does Natural Gas Get To Our Homesand Businesses?19 interstate natural gaspipeline systemsoperate within theNortheast RegionImage available athttp://www.eia.doe.gov/pub/oil gas/natural gas/analysis publications/ngpip22eline/northeast.html11

Natural Gas – Cont. Propane, C3H8, is obtained from naturalgas or from petroleum refining. Propane and/or butane are soldindividually or as a liquid mixturecalled liquefied petroleum gas(LPG) in small tanks.Propane tanks. Image available /pnupro PropaneAirTank.html23Amount of CO2 that is emitted into the atmosphere per unit ofelectrical energy produced is plotted for three fossil fuels. Burningcoal emits more CO2 per unit energy than any other fuel. Illustrationby Ian WorpoleNotes:Image available at http://www.naturalhistorymagazine.com/0506/0506 feature.html2412

Global Coal Production (1981-2007)25Image available at s/articles/000042/004262.htmTotal Global Coal Consumption (1965-2007)26Image available at s/articles/000042/004262.htm13

Historical and Projected Oil Production (1930-2050)Image available at s/articles/000000/000085.htm27Global Gas Production (1970 to present -projected 2015)28Image available at s/articles/000000/000061.htm14

Global Gas Consumption (1965 projected to 2015)29Image available at s/articles/000000/000017.htmEfforts to reduce pollution from fossil fuelsSO2 and NOx Acid Rain Program Scrubbers, electrostatic precipitator Clean coal technology 3-way catalytic convertersOther pollutants Reformulated gasoline Use of additives to boost the octane rating ofgasoline --- increase burning efficiency3015

31Efforts to reduce pollution CO2 emissions? CO2 will be produced as long as we continue burningfossil fuels3216

CO2 sequestration Process of depositing recovered CO2 (from burning offossil fuels) in an underground or ocean location Goal is to prevent its release into the air33FIGURE 7- 9 Potential sequestration sites for carbon dioxide.[ Source: Redrawn from Scientific American ( Feb. 2000): 72 79.]3417

Carbon dioxide destined for ocean storage could be transportedby a pipeline that extends to the depth required (Figure 7- 9).(1) Shallow injection (200-400 m depth) in the ocean- Works if the seafloor there is slanted sufficiently to allow thedense, CO2-rich water to be transported by gravity to greaterdepths.- Most of the gas would return to the surface and enter theatmosphere within a few decades if the CO2- rich water wassimply diluted by mixing with surrounding water, rather thansinking.(2) Deep sea injection (3000-5000 m depth)- Produces a pool of liquified CO2 (due to high pressure andlow temp.) which is denser than ocean water- Could take centuries to dissolve in surrounding water- Earthquakes could destabilize the pool, releasing massiveamounts of CO235CO2 sequestration (Figure 7- 9) – Cont.(3) Deep underground storage(a) Pumping into saline reservoirs, large formations ofporous rocks saturated with salty water (brine)- Lie well below freshwater supply- Caprock overlying the formation must be secure to preventupward migration of CO2(b) Pumping into depleted oil and gas reservoirs- These underground caverns are known to be stable- Good for storing CO23618

Removing CO2 from the atmosphere Process of extracting CO2 that is already dispersed intothe atmosphere(1) Iron fertilization proposal Involves adding iron to Fe-deficient oceans Fe induces plankton bloom CO2 is used by plankton during photosynthesis Potential problem: When planktons die, theirdecomposition will use up dissolved O2 and releasemethane and nitrous oxide (i.e. greenhouse gases)37Removing CO2 Cont.(2) Growing plants Would absorb and temporarily sequester CO2 during thegrowing process Potential problem: Clearing of ground to plant treesalso release CO2 into the air amount of CO2 absorbedduring growth3819

Reducing CO2 emissions by improvingenergy efficiency(1) Use of low wattage fluorescent light bulbs Replacement for incandescent light bulbs Payback period is a few years(2) Use of automobiles that burn gasoline more efficiently(higher mpg)3920

Fuels Used to Generate Electricity * Natural gas , CH 4 (methane ) - also releases CO 2 Combustion: CH 4 O 2 CO 2 H 2O Heat Nuclear fuel, such as uranium and plutonium Radioactive decay produces heat * Coal and oil - contain hydrocarbons; emit greenhouse gases like CO 2 when burned Combustion: CxHy O 2 CO 2 H 2O Heat