EPSS 101 - Lectures 11 & 12
EPSS 101 - Lectures 11 & 12
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Date Created: 05/11/14
pig irucjh f9 U3 f n 397 on v l f ll39lDl t vi Lecture l l Hydropower U3939 tt E35 ii i Et1rilT Energy Dirninisliing fossil resotiiczes rzinct prospects for o sustainable future Professor Etontl Paige 4 orliJ eel Electrllrol Eli er PE r t lltEquotquotquot Hydroelectric Power Fundamentally hydropower involves the conversion of gravitational potential energy to ltinetic vrm energy to electrical energy 3 Gravitational potential energy we a PE rn g h where m is the mass g is the gravitational acceleration and h is the altitude above a referen I th dnsi volume o a er lust ilike 1E per unit area for ihydropower KE e A p iv where v is the water velocity celevelthydrostatic head 39 at case ofi i T t to H to kg mi p V where p is nd V is the urn nr The conversion of water gravitational potential 39 projects Hydroelectric power accounts tor almost half of the 3 of the current US energy supply that is not fossil I fuels or nuclear Hydroelectric power accounts for 1 0 of electrical power generation in some countries Virtually all hydroelectric power is derived from owing rivers tidal and wave energy are relatively minor players if to ilclnetic ener very el l 1cient greater than 90 l energy can be til or large scale on 5 0 in S an i l i K iiii l at lloriiasii39tl hJ l PlZJUl Er is iiclrorJUt quotW title a aeese xkat nqpi g rggpsunuaauuarm i it nuQ ea nariiIe o39a39 a llydropoweir History Controlling the ow of water and harnessing it39s power has been a constant theme of civilization Watemheelsw e probably invented by the Greeks 4000 BC to do mechanical work such as milling A There is also evidence for early water wheels in China and the Arab world Water wheels were widlespreadi in Europe from Midieval times and also powered the earl i ea c of the industrial revolution quot if Waterwheel Configurations Waterwheel powered factory in Ireland Uu P2 C1 T EICJP t U39 T Cl C quot73 CL oppos I it I cut CW The Hydrologic Cycle HIE l lydropower derives from the 23 oil solar energy incident on the earth that evaporates H quot water z The latent he y of evaporation of quotH water tsp This is much larger than the T pical useable thermal energy of water which is on the order of 413632107 J ltg l Tu mse K K 20 C 63x10quot J kg 39 4 M Water vapor is therefore a potentially powerful 39 quots quot my form of energy quot 1 i Most ol the energy contained in water vapor is r eturn ed lo the enviiroznmenl as heat when it 1a Gtlohal evaporation river llow in 1 ltm3 per year condeinses but a small fraction is tzoinverted to gravitationail potential energy t ulltirnately heoomes the ltinetic energy of llowing livers Water runoff is organized into drainage basins which feed increasingly larger rivers that r quot3 eventually flow into the oceans Rivers g represent very concentrated forms or energy quot a g Global river llow is 43x1l39lquot kmquot per year Approxirnately 10 of the kinetic energy of owing rivers is currently converted to 1 3 electricity which equals 17 or global electricity i 1 air 6 M NT lost chergtl in W ll l V lmr ifilit ilitLtl39l Wt at Cinril39 5 citll L15 liitlte i WhE 393939 utictlaekl ll3t U lC39I I quot39l 0 ll lEll5 C inquot t39l tilill E I lJ ltT39Uquotl39U l lUquotlr grddl 8 ll lr p 0 lJ t C1 FB B 4 ClUJ39l 3 1 ULIJ Ihl B I Ru noftheriver hyd roelectrlc plants a in locations where there is a substantial natural river gradient eg waterfalllst h39vers can be diverted into lurbiries to generate electn39cily V 1quot Rlunoilttlle riverinstallations are the rrtostcosl ieclive p 9 39 0 hydlrolpower systems to install arllcll deperldingl orl the fraction of river water diverted the least egg 39lgi gr rlentally grfnaging ii i 6 Because of their high costbene t ratio most the best large and small scale runoftheriver lhydroelectric sites are already utilized v in l Typical smallscale runaolsthenver installation 75 or the nlonnlal flow over txliagara quot3934 Falls is diverted to generate 4 SW ol 391 1 electrical power l39ll ll lhl 3 umleur l39l ltv lf r1Et739t39 lT3Q9d lml lrlrr39f ZlltCl fllo uettfr lgtUt lO Jt Pumped Hydroelectric Storage 6 No river No problem i Energy cant be efticielrltly stored by purnpinlg water into elevated reservoirs and then retrieved by quot E lll l R EV letting the water flow back down quot quotkt H Beauty of the system is that the quot H same turbines that draw electrical power to purrlp the water can be run in reverse to generate electrical power when the waiter runs in the opposite direction The overall et ciency of the system is close to 75 There are 140 pumped storage systerns operating in the US with a combined generating capacity of 18 GW Purnped energy storage facility tg 39 quot aural W 1 North eld Mountain Pumped Storage Facility 39U 1l 39 U tnlfl it if U i quot l ilrli ll llncl tililrrl li LlU CY llllhl negfllpd lquotrllll ll0 lI E3939 P L7U3 QV r lltrl tor l tJ39lFrfl9lE Q l l 39tl9 Lil Lullr l ltlCl39ti rtquot 3t39o 1 l C quotlll lrquot lrli rquotolJ gyll Cl Cl CW1quot Hyd roelectrlc Da ms Hydroelectric dams impound a reservoir of water that can flow through turbine electric geinelrators orl rderrlagd W 5 T The power produced is P s p g h r is where p 39 39 3 is the density of water g is the glralviltational r w T acceleration h is the hydrostatic head r is the 1 vg new i rate of water ow mivsec and k is the 2 5 39 x ef oiency typically 09 The largest hydroelectric plants provide 10 times the power of tlhe largest fossil fuel or nlucllealr plants T r39 quot39 l2 Storing water behind dams potentiallly enables the utilization of the total ow of a river which E Ai may experience signi cant seasonal variations 39 E j E j39 39 The ability to instantaneously control the flow of water to turbines makes hydropower T j quot effective for handling quotpealting power loads l due to temporal variations in demand tirrle of p 7 y day hot weallter etc 1 Water storage behind darns can also provide additional benefits such as fllood control irrigation and recreation u o Hlltltxdl M Di lQlLL title wcller IlHquot HJ V H lCL JlJlt tal lril39 liorrtecl 7tJ39tJllL395 l lo iquotl l quotnll ll J V N W Dam Construction Dams require signi cant quantities of materials and detailed engineering to withstand the pressure force of R the lrrlpounded water and its effects over time PI The simplest dams are gravity darns that rrlay be constructed of rock till to provide males and soil for seepage control Gravity dams are most often built in wide canyons Arch and cupola dams are built of reinforced concrete and are most often built in steep canyons j39 K iquot quot4F rrle goal or the dam builder is to find a site that will l l l T provide the most water storage for the least cost 0 IT 3 3 Large darns represent major public works projlects T can oltert costing tens of billliorls of dolllars The energy costs of most successful hydroelectric projects are more than offset by their energy prodluction The average EPR tor hydroelectric systerns is 225 the highest of all energy systems Hoover Darn Site Hoover Darn Construction llolquotr pB Lt tW15 lllquot39t7 1 l 3tllJl 3 of lltfP Ct I l ill L fFquotr frl l tj lll e5 5 lli39C li JlquotC 5 Dam Ownership and Operation 39 Dam construction in the US peaked in the 197039s as the number of good sites becarne rnore scarce There are approximately 75000 dams in the US alone of which only 2400 are used for hydropower They are owned and operated by a variety of organizations most of them private companies rueE Hug t mta 1 d I M l I Dam Construction in Canada Us Dam Ow ership Aswan Dam Mill Rrver Egypt Glen Canwn Balm F39ll i R Gritgee mm Yargtgg Coiorada Rreer USA Raver Cher onewe Coulee P Golambaa River USA Human and Environmental Costs of Dams Dam construction has resulted in a wide range of intended and unintended environmental costs Some of the most important of these include Loss of land due to permanent ooding 1 Displacement of indigenous human populations 80 million worldwide Permanent loss of wild river canyons wildlife scenic value recreation more than half Effects on inter ecosystems Redutced downstream annual floods sediment loads interfere with river ecosysterns nutrients and farming l li5le N E I Vamjeyj Barriers to upstream and downstream jrsh T mi lradionfpr awnin sh like salmon T Permanent disruption ofzriver ecology due to alterations of river temperatusre lower for high dams higher for shallow dams Greenhouse gas emissions due to the decomposition of submerged vegetation Ghosttown in Chin before ooding by Three Gorges Dam Darn Economic issues 39 Much of the present declllne in new darn construction can be traced to economic issues Analogous to mi itary spending one of the most important dnvers for new clam projects are large dam construction conliractors who have an obvious pro t stake in developing new projects and use their political in uence to initiate new projects New dam projects are often sold on the basis of net costlbene t analyses Historically Ute actual costs of most large public works are rarely underestimated The average nal costs of dam construction projects are gt15 times their basis for approval estimates which in many cases results in costibenelit ratios of greater than unity Historically the bene ts of dam projects have been systematically overestimated River flow predictions have often fallen short of predictions while water leakage rates into porous reservoir bed formations and evaporation rates from the surfaces of reservoirs have been grossly underestimated Reduced river ows and increased evaporation rates are increasing over time due to global wanning resulting in many reservoirs being permanently underlilled The useful iliiotimes of dams and reservoirs have also been overestiimated as welt Rivers carry suspended silt loads that are deposited in the still waters behind dams resulting in resenrolir llite tin39ies of only 50 years for some darn projects La a Powell Record Low Water Levels tlrtclarei ti ti39Tlrt39t cl 4 UH titre a r toi are it if cl wtl tel low ti r w i h rn rlti E ll be til fit 9 5 Dam Failures Due to the enormous potential energy they hold back dam failure is a constant threat Dam failures have resulted in 10039s of thousands of fatalities during the last 100 years Notable dam failures 1928 Saint Francis Dam near Valencia fails 3 minutes before midnight 125 ft wall ofwater kills 385 1963 ValJont Italy 250 meter high tsunami 2000 deaths 1975 Banqioa Reservoir Dam in China fails causing 36000 fatalities downstream t are Teton River ildaho 100M earth dam fails killing til people and t3lDdl head or cattle 28 in darnages claimed t3tJttJM in damages paid 5 3q 7 t ti or every total dam failtulrei there are dozens f A o i i of dam incidents caused by floods 390 i etc Stone Canyon Reservoir Dam Relm Va As dams build in the 20 oentury reach their design Iiifetimes or become zunsatey there is growing pressure to remove t t to their natural state More than Sm dlarns have been removed during the past 50 years Integrated over the life of the restored river system dam removal is very cost effective arid provides some of the same shortterm stimuli to local eoonornies that dam construction provides UCLA lies in the ood plain p 4 of Stone Canyon Reservoir e 39 t Hwy water storage reservoir in Bel Arriamlltwoitx N quotJUST Elzuilt in l9239l the reservoir 5DlMlN39l39 c s iv F has a capacity or 34 million galillons It had been scheduled for removal in 2004 Flwar restoratliori HIn D Hesemlw arr P scenam lllustm ion TDvIJ1Jl39lquotI39e Rtwe Norm ol ll r39 and hub by the CW OI San Fauna11l in 1923 rquott i ll ll53 tli io rnole l39lli I39ltr tj llluilFlllj tttJrttE r Cltt j l it Dfartltt lat lquot lVPUlalVljN tilt ttt The Fulture of Hydropower Hydropower remains one of the most l u 39f quotquotquot quotquotquot 399 l proven reliable and oost elquotfective renewable sources of energy Global hydroipower is expendinlg at a rate or 15 per year The rate of expansion is more than 8 per year in China The expansion of hydropower is limited by the Earth39s water cycle the T A unavailability of suitablle development 1 1 R 1 T sites regulatory hurdles environmental e W T u W 5139 quot llradeofls and uncertainties in climate predlictions Hydropower is likely to Continue to be an important part of humanity39s sustainable energy iportl39olio for some time to come in 3aw t it iwi Biofuel Origins y 4 Biofuets are created through photos powered by sunlight 39 O lithe chlorophyll pigment absorbs photons at blue and T red wavelen 0 O O 9 The photosynthesis reaction roduces glucose nthesis which is Lecture 1 2 er ii quotii tii p ECO EH20 V CsH12Oe 39 502 2 The reverse reaction is res iratiogo btirnin Burning biofuel results iri no net Cgzernissions j e The photosynthetic process is regulated by t 3lant39s H f 4 P T r 0 T stomatal pores which can open and close UCLA EPEJ 1399 J Emm Emmaquot Plants can t take in CO2 for Photosynthesis without lfrir39riinishing tossiil resources cincl loosing water vapor which saturates their pores when i1rrJ35eris for o tJ5C1ilgtFi it3li iUiUt39Ze 0395 T T 1 Plants in dry climates can39t afford to loose water so they let in very little CO2 an 39 Pmressm EQWJ page i The net photosynthetic ef ciency of most ecosystems t l the ratio of the net chemical enerquot i irodlucecli relative l to the incident solar energy istroughly i T T lioweyery it s not this simple since bioiuels are not H quot 39 quot quot continuously accumulating on the Earth s surface quot39 ijT quotr39 CEFE 1iL39 eii 39li l t ilquotl T ii1 Wt it Q irlt llli2D il l Tiiiilii l Ul cyg F R N Glucose quotDryquot Biomass Composition 39 To rst order the creation of organic T y T T Cellulose C3H10O5 carbon by photosynthesis is balanced by TH E CAR 30 me 0 39i Linear chain of thousands of Cellulose destruction by respiration and decay CYC L E quot linked QIUCOSE Units The residence time for surface organic carbon is 20 years A small fraction of organic carbon and carbonates are buried in marine sediments where they reside for 1D0 million years Sediments are ultimately heated during sulbductioln and release 002 back to the atmosphere Structural parts of plants Fiber constituent of piaper T T textiles etc rm quotii ij i tquotquot 4 Only digestible by bacterial in mminants termites Hemi Cellutose Non starch component of plants Only digestible by bacteria Lignin Fills the spaces between cell walls to make them stiff and waterproof common in wood iT wew was Only digestible by bacteria P quot quot39 39 Other 39 i X 39l39El39 quotE quotJ 3939 Oils sugars minerals etc l 39i3939 39r 39 3939 3939 39quotquotquot39 quot many oil which are digestible II by humans if not poison Raw biomass is 2030 water by mass Inrwars1 um M3 1T39ttlCjf39 O 392 C gtquoti D p y J5 p L31 E k i i tj vr d3 h7 be t 1391quot Dtghin lu3 IEM l r Iwgtl39 g role xii aqfggi I l i l l i iii39 J 9 l I l I ri39amp U quot1 it 011 1 1quot rne39v Biomass Combustion Direct combustion same as respiration is the sirrtpiest approach to harnessing biornass energy The homo species has been utilizing biomass buming as an energy sou 1rniion years Biomass burning iplrod uoe 1B20 MJFK of olry biomass compared to 28 MJi39lltg for bituminous piziel srid3cL39quotL kQIoLJignitecbalt 1 B quote nn7tJdynamitcl efticiency of wet or damp biomass is considerable lower due to the high a ehTlt39W6l V TElzatlor1 oFTArTh r1 Burning biomass in open res produces incomplete combustion paitisullates and toxic vapors Wood Burinirig Wood Pellets Wood Pellet Diesel fuel can be produced from rapeseed and soybean oils waste vegetable oils animal fats and some types of algae v The production process involves removing water and contaminants and then treating with a solution of methanol and lltOi l and then puri ed to produce biodiesel Jaipdiesel is superior to conventional diesel fuel due to its veg low stiltg lr content and pleasant aroma Except for the utilization of waste oil biodiesel does not produce net energy Biodiesel Biodiesel PFOdlJClZlQn It is alga possible to Burning ef ciency can be substantially increased 5t0V quotquotquotquotquot quot quot quotquotquot burn pure vegetable by improved stove design and piretprocessed fuel wan mm gill in same diesel Wood buming accounts for 35 oft f fsil quotquot39 quot engines with fuel non nuclear energy pro uction in the US amm m modi cations to the Paper and woooi product cornpanies use wood i 1 H I t t combustion for electrical power generation i Wood Fired quotquotquot quot quot quot39 39 we W3 em 0 as B account for the Power Plant mm U 6 higher viscosity y quot39quot quot M39 Biodiesel l quoti i39I l ft 3931 iii R trill bR r i1l i 75 V1 lquot J ON t 39 m l s sin 1 all I H I M VF 1 4Q P J W ity iii latl at P 4 lU l ii tr l 39 r 7 K WL y t 393 3 t if iii 3939eaquot f C O I U I 1 E in E iii Ll it r 393lt L l i Eti lT l397 E LN Q 397 5 h quotm ll w i p l l A l i ii in no t rl LC K i Fir J i l CC H W at s i n i 0 39 l st 1 tit til iiF i B iltl H I ftzndigg Biogas W Anaerobic decomposition of organic matter can be a source of methane gas Reaction CEHHOG gt 3C0 3CH p G Fermentation is the incomplete oxidation oforganic compounds in which Fermentation cEii2o 5 zicgnsohi 2002 239 2 39 The 03 M99195 3 V Sanita o District the electron acceptor is another organic 2305 KJm0l 2X 1370 RJITi0 operated a ianolliiis in the Septiilv39edai Pass iunltill moywecme rather than mqmecmayr mcygen 1980 when it was converted intoa G i 39 d l d f t i H H championship golf course and the Montaingate aseous an 39qLquot ermenta 390 l 5 Cmnm Cm products may have considerable energy H Vi 039H P P 08 6 Gas is drawn from 125 wells at depth of 60 120 ft below the surface 4 million standard cubic feet of gas are produced every day and piped directly to a 40 Megawatt co generalion plant at UCLA providing 8 of UCLA39s power The oxy en content of the gas is closely monitored If it rises to gt1 the flow is immediately shut down Bmgag mmm5min matter by loacterla to produce Products mm mg 5 methane and hydrogen gas um OH so 395 happens in cows and people Carbon dlcnldltl 0 1391ii Hluugon lit g it39Cl Hyilicgirn tel 91 if i Mmmmm M H produce theirown heat Mauntaingate Biogas Plant Om p Mk l 39 lnllvl 7 3 3937 i at 9 r39u t l z 0 PQ S ir 1 HLNEil39t lLlll 39ll lquotlll li fL llH lite ll l ilifi ij ftilf i il till it ii in Lt tr re 3 Examples of fermentation Fermentation reactions are generally anaerobic and exothermic and thus Ethanol C2H5OH Eermentation of sugar by yeast or bacteria to make ethanol beer wine etc Creation of animal muscles when oxygen supply is low Anaerobic digestion of organic Fermentation t iwquotitquot39lHI tfu 39Wt i i39lI l39rL inn ii i x Lt ti E 1 quot5quot l 9 C L it i Pr iquot39i i jie lgwj TlquotC V I O lrl l quotquot1 F H 17 1 rife t1ll E llquot Annual Fuel Ethanol Production by Country 20020 1 1 Top 10 countrieslregional blocks Millions of US liquid gallons per year 0 9 Ethanol Liquid ethanol is a power pacled fuel containing 311 MJkg compared to octane which contains 444 Mlcg It can be produced easily from the fEl39mE39l39ltall0l39l of World CountrylRegion 20111 2010 2009 2008 2007 sugar from corn or cane T rank F 1 i is 18900 13231 10638 9236 6485 u39 4oi I 05an 7 F i 7 0 mm 3 2 0 557324 092154 657789 64722 50192 mL 5 L quot j 639 3 iE39 1 39 71 39 391 119931 117688 103952 73300 57030 gr 4 55476 54155 54155 50190 48600 39 I 5 43520 6860 7620 I quot M6 4623 35663 29059 23770 21130 M quot39 39 mm W 39 8 9167 6600 5280 3 no 6 1 8 P 8321 17930 7490 Ethanol can be used In distilled form or blended with gasoline cleaner buming but hardelstarling 9 0 q 2 PR 872 6604 5680 2640 2640 For ethanolgasoline mixtures the percentage of ethanol by volume gives quotEquot numbers 539 7393 E10 or less Gasohol 10 other 24727 E35 6 Hlglhlasl ellnalngl mjxmlre sold in UIJSA Applroximately 65 of Iowa39s corn production currently goes to making ethanol fuel pure i5med1 emanm ggmginls 5 h drated water 190 proof can also be used as a fuel 9 in Brazil ethalnoll plroductionl flrom sugar cane alcoourlls for 18 of the country s total energy Only100 pure alcohol 1200 proof fan be blended with gasoline to exclude water utilization and 40 of its energy utilization for tranrsponationl 39 Lll ri l l ll I E39quot 9 H l l5 1 l 1quot 11 in 0 l l1lE l 11 I quot1 394 1 E 03951 E39lZ W1 0 l llJ f7 llquotlI39 t till lhfl Tl 1 u i ll F H Q ll jl glf ll Ell in lZ39i39ll1 r39 ll Lil ll lJ1l1l1l rt 15 J H Q 7 Home 3014 mrmmd wwoodlst 1 ll 395quotlht 1quot J 39t39l T 11123911 l 1 1 l lquotil l l 1mf d l l 1i39t1u fJh Cll5l U or quot39 l U 39 1quot J 4 I F If it I ll 1111187 6 1 4 w 1 Pn T 3939391l 39 1 L 1 5 39 1 T1 1IquotLquotL 139 l L j r quot1 quot1 ll 1 r39l1quot1l 391 lF395lU l 9 r Idfl39quot 393 Til1l rs Kl h olnosoltlu rljrl 131 H U Mllfllmall to l39l1e1gatiue lnet1en1ergy produlcti1on 39 39 P Displaoesfood reduction and wate resources Unsustalnable agricultural practices Soil erosion Nutrient depletion llll39lClf8lSeS1 corn prices 1 The US government provides 9 billion in ethanol subsidies to make1 ethanol competitive with gasoline 051 per gallon federal blenders credit 39 Com sulvfsldles quot g Oils and sugars produced by algae can be 39 TEX ClfBl3lltS B110 4 f39 gU I Land Baquirerdtntlispllacs lllll laaalline 1 1 1 I 1 F 3 I 1r nsalim 3939 Pl quot i llhIlUl39Ii139lII1 S1llB3 High tarllquotfs on lmportecll corn and ethanol 7 1 Ngae pmdU3ww per unit area can be 9 ll la2l4 much higher than conventional crops 9 4 t The future may lie in cellulosic ethanol in s I f y a infrastructure costs mallt6 algae 3 quot 39 which enzymes are used to convert cellulose 393 1 39 farming experlsive r K B to SLlgar and the sugar is fermented to make P quot 0 s 39 Genetic engineering m393 eVEquotlUElly malt 1 s amend s c M M 1 H I ll 1 0 algae an e1con1oln1llcally ulasble bloluel quot 6 7 Camplu ampd from w 5 2 5 l lLhl 1 13 9 ln a postfossil fuel ecorlomy blofuels may quot ii 9 1 be the best option to provide liguid fuels quot grass and other wlld biomass that requires no MM u Jquot mLigm l mich are necessary for long nge fr Mm 1 cultivation or lrrlgatlon transpona on 1 r i 1 I il 8 7 0 7 quotquotquotquotquot 139r1ll1rrquotr lr lquotl fr it I i v 1 H E 73 W i F c I J I f ft 1 l39jL1ii H lt ll 1 1l 39r ll ll U 1JU quotlj EIHr 0 ll l iji swr 7 U F quot 39 C1ll quotquotl l L7 R ill 395 p3 lquot39U y l1 51 1quot1l1v9 l ll ll ll
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