Energy101_Module_16.pdf

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Energy 101Energy Technology and PolicDr. Michael E. WebberThe University of Texas at Austin

Module 16: Renewable Energy VI: Bioene


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Bioenergy Has Several Forms

Biomass:Typically for heat

and power

Wood, straw, bagasse, cow

dung, waste

Lower energy density thancoal

Biogas:Similar to methane

or natural gas

Mostly CH4 (60-70%), with

a balance of CO2

Made from decompositionof organic wastes

(e.g. landfill gas)

Biofuels:Liquid fue

Ethanol, biod

biobutanol

Lower energ

gasoline or d


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There Are Several Pathways For Bioene

But They All Start With Biomass

Biomass to direct combustion: heating, cooking, power generaWood stoves, wood boilers, pellet stoves, waste-to-energy power plants, etc.

Biomass to biogas for combustion: heating, cooking, power ge

Landfill gas capture systems, anaerobic digesters, etc.

Biomass to liquid fuels: transportation

Biorefineries for alcohol production, etc.


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Bioenergy Resources Are Abundant Nati


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Bioenergy Is Attractive For Several Rea

CO2 is consumed during growthbecause of photosynthesis

CO2 from combustion would ha

released from decomposition a

Renewable

Domestic

Feels natural

Department of Energy


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Bioenergy Has Several Drawbacks

Land-intensive

Water-intensive

Concerns about indirect land use changes (such as

deforestation) in other parts of the world

Invites moral dilemma of food vs. fuel

Inecient use of photons


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Biomass


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1.3 Billion Tons of Biomass Are Availa

Renewably on An Annual Basis

Concluded in a landmark2005 USDA/DoE study

Known as the Billion Ton Study

Logging residues, wood waste,

manure, crop waste, tree

trimmings, yard clippings, etc.~10 MMBTU/ton

~13 Quads available (upper limit)

nationallyDoE


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Americans Generate 250 Million Tons

Municipal Solid Waste (MSW) Annua

0

60

120

180

240

300

1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

TotalMSWG

ene

ration[MillionTons]

Year

Michael E.

Total MSW GenerationPer Capita MSW Generation

19602010 U.S. Municipal Solid Waste GenerationSource: U.S. Environmental Protection Agency / 2010 MSW Characterization Fact Sheet Graphic: Michael E. Webber, The University of Texas at Au


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Much of the MSW Stream is

Energy-Dense Fibers and Plastics

Paper and Paperboard

Glass

Metal

Plastics

Rubber and Leather

Textiles

Wood

Yard Trimmings

Food Scraps

Other

0 20 40 60

Annual MSW Generation [Million Tons]

2010 U.S. Total Municipal Solid Waste Generation by MaterialSource: U.S. Environmental Protection Agency / 2010 MSW Characterization Fact Sheet Graphic: Michael E. Webber, The University of Texas at Au


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About Half of MSW Is Landfilled; the Re

Recycled, Composted or Incinerate

Total MSWGeneration

250.4

Total MaterialsRecovery

86.9

Discards AfterRecovery

163.5

Recovery ForRecycling

66.2

C2

Retur

R2

Total MaRecyc

58.

Discards ToLandfill134.2

2011 U.S. Annual Solid Waste Flow [Million Tons]Source: U.S. EPA/Alex Breckel Graphic: Michael E. Webber, The University of Texas at Austin

4.4 pounds of MSW

per person per day

1.5 pounds is composted

or recycled

0.5 pounds is incinerated

2.4 pounds is landfilled


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MSW Can Be Used Directly As a Fuel So

for Power Generation

Waste Incinerators: Direct generation of electricityKnown as Waste-to-Energy (WTE) or Energy Recovery

Unpopular in the U.S. (because of concerns about emissions)

As of 2010, the US only had 86 WTE plants with a total capacity of 2.6 GW

Popular in Europe (because of land constraints)

Total annual generation potential:

~29 million tons/year

~10 MMBTU/ton

~300 trillion BTU/year (small part of overall mix)


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Unrecycleable Plastics And Fiber Resi

Can Be Turned Into Fuel Pellets

John Fye

Mechanical dies extrude the fuel pelle

John Fye


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Solid Recovered Fuel (SRF) Pellets Ca

Used To Displace Fossil Fuels

John Fye

John Fye


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Why Cant We Just Use A Bunny As

Renewable Energy Source?

After all, it keeps going, and going, and going

Energizer Bunny design is a trademark of Energizer.


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Bunny Power is Another Source of Ene

Thousands of rabbits, some ofthem pets abandoned by theirowners, are being shot, deep-

frozen and burned in a heating

plant in Sweden.

The frozen bunnies are shippedto a heating plant in Karlskoga incentral Sweden which uses them

as biofuel and incinerates them

to heat homes.


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Biogas


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Organic Wastes Can Be Turned Into Bi

Via Anaerobic Decomposition

Organic wastes can decompose two ways

Aerobically (in the presence of oxygen): organic wasteCO2

Anaerobically (in the absence of oxygen): organic waste CH4

Biogas (or renewable natural gas, aka RNG) can be used julike natural gas


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There Are Several Organic Waste Stre

Landfill Gas: Mining for biogas from anaerobic digestion of M

WTE is direct use of MSW, landfill gas is indirect use of MSW (with time delay)

Landfill gas capture and use is already in place today

Municipal Wastewater: anaerobic digestion of sludge

Agricultural Operations: anaerobic digestion of manure


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Cow Power Is One Possible Solutio

Agricultural manure to biogas through

anaerobic digestion~100 million tons/year

Enough for ~2% of annual electricity

Creates a 2nd revenue stream for farmers

Turns an environmental liability (manure)into a valuable commodity (fuel)


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Biofuels


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Recent Policies Have Prioritized Biofu

Especially Corn Ethanol, To Displace Pet

Mandates to purchase biofuels

Ag subsidies to make the biofuels cos

Tax credits to make it cheaper for con

to purchase biofuels ($0.51/gallon)

Expired 1 January 2012 (after $20B of subsidies)

Taris on imported ethanol ($0.54/g

Expired 1 January 2012


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Energy Independence & Security Act of

(EISA 2007) Called for Aggressive Penet

of Renewable Fuels

0

10

20

30

40

2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2RenewableFuelsStandard(RFS)[Bgal/year]

Year

20062022 U.S. Applicable Volume of Renewable FuelSource: 202 of EISA 2007 Graphic: Michael E. Webber, The University of Texas at Austin


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The USA Essentially Has A Mandate fo

Todays consumption:140 Bgal/year gasoline

40 Bgal/year diesel

EISA Caps Corn-Ethanol at 15 Bgal/year by 2

~10% of annual consumption in 2022


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Biofuels Terminology

First letter indicates the fuel B for Biodiesel (regardless of source)

Not clear how to label biobutanol

E for Ethanol (regardless of source)

Second number indicates the peSome standard biofuel blends

B5 = Diesel blended with 5% biodiesel

B20 = Diesel blended with 20% biodiesel

E10 = Gasoline blended with 10% ethanol

E85 = Gasoline blended with 85% ethanol

Mariordo Mario Roberto Duran Ortiz


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Alcohols Are Just Hydrocarbons with an

Ethanol = Ethane + OHEtOH

C2H5OH

Methanol = Methane + OH

very poisonous

wood alcohol

CH3OH

Propanol = Propane + OH


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There are Several Dierent

Sources of Ethanol

Starches: Corn, etc. (ULeast amount of energy return

unit mass

Process into sugars, then ferm

to alcohol

Warren Gretz / NREL


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Sources of Ethanol

Sugars: Sugar cane, subeets, etc. (Brazil)

More energy output per unit m

than corn

Ferment directly to alcohol

Warren Gretz / NREL


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Sources of Ethanol

Cellulosic Materials: Cowood chips, switchgras

Grows without irrigation, tillag

topsoil erosion

Not everyone agrees with the

Requires enzymes to break doEnzymes is another word fo

Pat Corkery / NREL


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Ethanol Has Some Benefits

WTW CO2 reductionof 1952%

Oxygenate for CO

Higher octane (108

allows higher

compression ratio


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Alcohol Fuels Have Drawbacks

Ethanol has lower energy content than gasoline by ~30%

Sparse refueling and distribution infrastructure

Ethanol can corrode conventional pipelines

Build dedicated pipelines, or

Transport fuels by truck or rail (using diesel fuel)

Source: National Corn Growers Assoc. & Andrews & Jelley


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Corn-Based Ethanol is Problematic

Requires about as much energy tomake as it yieldsConsumes vast amounts of fossil

fuels at the farm

natural gas-based fertilizers

petroleum-based herbicides and pesticides

heat for fermentation from natural gas or coal

diesel-powered trucks and farm equipment

Limited land capacity

Corn cannot be piped, sousually trucked (using diConsumes vast amounts6 gallons H2O/gallon ethanol for p

6001,500 gallons H2O/gallon et

growing

Expedited topsoil erosionNegatively impacts the nitrogen c

growing dead zone in the Gulf of


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Biorefineries Are Smaller Than

Petroleum Refineries

Biorefineries for Ethanol Production209 biorefineries as of January 2012 with capacity for 14.9 Bgy

Source: RFA, Feb 2013

Petroleum Refineries for Gasoline Production

149 refineries as of January 2011 with capacity for 140 Bgy

25% fewer refineries with 10x higher overall output


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Brazils Ethanol Miracle Has Severa

Key Dierences

Proalcool Program Started inthe 1970s

Dierent air quality laws

Cars are all flex-fueled with on-board computers to adjust

between fuel mixes

Market system allows for easyprice comparison

Brazil uses sugar, not cornHigher energy content per unit ma

Does not require irrigation

Does not require fertilizers, herbici

pesticides

Grown for ~500 years without dep

topsoil (Brought to Brazil in 1532 bAfonso de Souza)

Sugar is semi-perennial, NOT annu

Three crops/year, replanting every

Source: Milton Maciel; EIA; ASME


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Biodiesel Looks Appealing

Uses waste and many non-food cRestaurant grease: tailpipes smell like tortill

Can help avoid food vs. fuel dilemma

Similar energy content as petrol

based diesel fuel

Rudolf Diesel demonstrated his

engine at the Paris World Fair in

using peanut oil

Alabama Inst. for Deaf and Blind


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Biodiesel can be Made From

a Variety of Feedstocks

Soybean Oil: Most common sourthe U.S.

Canola (Rapeseed) Oil: Most com

source in EU

Palm Oil: World production exceesoybean oil and concentrated in F

Main producers: Malaysia and Indonesia

Warren Gretz / NREL


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Biodiesel can be Made From

a Variety of Feedstocks

Coconut Oil: High concentratsaturated fatty acids

Beef Lard: Fat obtained from

restaurant grease, etc.

Algae: High potential product

but experimental

Pat Corkery / NREL


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Biodiesel Is a Leading Cause of

Deforestation in Malaysia

Source: National Geographic, November 2008


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Its going to be hard to grow

way out of this problem


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Dr. Michael E. Webber

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Energy101_Module_16.pdf