Let’s envision an ideal biofuel process

Let’s envision an ideal biofuel process

FeedstockFeedstock

CO2

BiomassBiomass Biomass

Plants Animals (by way of plants)

Plants Use solar energy to convert water and CO2 to sugars through the

process of photosynthesis Harvested portions of live plants or remains are sources of biomass

Animals Consume plants (or consumers of plants) Elimination products or remains are sources of biomass

Virtually all of our current energy supply is derived from biomass (fossil fuels are just “well-aged”)

Multiple FeedstocksMultiple Feedstocks

• treestrees• grassgrass• agricultural residuesagricultural residues• energy cropsenergy crops

• municipal solid wastemunicipal solid waste

• sewage sludgesewage sludge

• animal manureanimal manure

7878

10.910.9334.34.3

400400

330330220220

U.S. Biodegradable Wastes

Municipal Solid WasteMunicipal Solid WasteSewage SludgeSewage SludgeIndustrial BiosludgeIndustrial BiosludgeRecycled Paper FinesRecycled Paper Fines

Agricultural ResiduesAgricultural Residues

Forestry ResiduesForestry Residues

ManureManure

AmountAmount(million tonne/year)(million tonne/year)

Alcohol PotentialAlcohol PotentialWasteWaste (billion gal/year)

10101.41.4

0.40.40.50.5

5252

43432828

TotalTotal 1,0461,046 135135U.S. Gasoline Consumption = 130 billion gal/yearU.S. Gasoline Consumption = 130 billion gal/yearU.S. Diesel Consumption = 40 billion gal/yearU.S. Diesel Consumption = 40 billion gal/year

How to Get Liquid Transportation Fuels from BiomassHow to Get Liquid Transportation Fuels from Biomass

Convert sugars and starches to ethanol – fermentation

Convert plant oils to biodiesel – transesterification

Convert anything to liquid – pyrolysis Convert anything to gas (gasification) with

subsequent conversion to liquid – aka biomass to liquids (BTL)

The Challenge

Jet Fuel

forestforestwastewaste

corncornstoverstover

switch-switch-grassgrass

Gasification to “syngas” (CO + H2)

Diesel

Gasoline

LignocelluloseLignocellulose

Fisher-Tropsch

methanol

Gasolinecorncorngraingrain

sugarcanesugarcane

starchSaccharification lignin burn

Enzymatic Fermentation Ethanol

Pyrolysis, fast or slowgases

bio-oil

sugar

Sugar/starchSugar/starch

Liquid Phase Processing

Dissolution

Can we achieve sufficiently high yields of targeted chemical compounds from solubilized biomass fractions to justify the cost of biomass pretreatment?

Biofuels, in Order of Maturity, p1 of 2Biofuels, in Order of Maturity, p1 of 2

Adopted from NREL (2006) http://www.nrel.gov/biomass/pdfs/39436.pdf

FUEL SOURCE BENEFITS STATUS

Grain/Sugar Ethanol

Corn, sorghum, sugarcane

High-octaneWidely available sources

Commercially proven

Biodiesel Vegetable and seed oils; fats and greases

Increased fuel lubricity Widely available sources

Commercially proven

Gasoline and diesel blends

Ethanol or biodiesel blended with petroleum fuels

Relatively straightforward for refineries to processDecreased sulfur emissions over standard fuels

Commercial trials in progress

Cellulosic Ethanol

Grasses, wood chips, and agricultural residues

High-octaneLess demand on agricultural lands than grain ethanol

DOE program targeting 2012 demonstration

Butanol Corn, sorghum, wheat, sugarcane

Low-volatilityHigh energy-densityWater tolerant

BP and DuPont in progress

Biofuels, in Order of Maturity, p2 of 2Biofuels, in Order of Maturity, p2 of 2

FUEL SOURCE BENEFITS STATUS

Pyrolysis Liquids

Lignocellulosic biomass

Can utilize waste products Potential source of aromatics and phenols

Several commercial facilities produce energy and chemicals

Syngas Liquids Various biomasses

Can utilize waste productsCan be integrated with fossil fuel sources (e.g., coal)High quality fuel

Commercially demonstrated a large scale using fossil fuels; biomass projects underway

Biodiesel or jet fuel

Microalgae High yield per acreCould be integrated with CO2 capture and reuse

Demonstrated at pilot scale in 1990s. Many start-ups currently underway

Hydrocarbons(designer fuels)

Biomass carbohydrates

Generate synthetic copies of current petroleum derived feedstocks

Laboratory-scale research

Adopted from NREL (2006) http://www.nrel.gov/biomass/pdfs/39436.pdf

Ethanol (EtOH)Ethanol (EtOH) Chemical Composition

CH3CH2OH or (C2H6O) Ethanol is ethanol – source independent

Also known as ethyl alcohol or grain alcohol 2 types:

Biologic: conversion of starches to sugar followed by fermentation of sugar with yeast

Synthetic: acid catalyzed hydration of ethylene Blending

Currently used as a additive (10% max) to improve performance (octane) of gasoline

Internal combustion engines must be designed to accommodate ethanol content >10%

OH

Ethanol SourcesEthanol Sources Most common sources are plants with high sugar

or starch content (e.g., corn, beets, cane, potatoes) Sources with more complex cellular structures

(e.g., wood, grass, stalks) require more effort to extract available sugars (cellulosic ethanol)

Biodiesel or FAME (Fatty Acid Methyl Ester)Biodiesel or FAME (Fatty Acid Methyl Ester)

Chemical composition Similar to petroleum diesel fuel in structure (straight chain)

and number of carbon atoms (10 to 20) Differs in that it is oxygenated and has a small number of

double bonds Fuel characteristics will vary slightly depending upon

source Blending

Completely miscible with diesel fuel Used as an additive (5% max) to increase cetane and

improve performance of diesel Internal combustion engines must be designed to

accommodate fuels with FAME content >5%

Biodiesel SourcesBiodiesel Sources

Plant oils Soybean Palm Rice Cottonseed Rapeseed (canola)

Waste oils (plant and animal) Algae – recent interest because

High amounts of oil Minimal competition with food crops and crop land Can be grown on land with low potential for CO2 sequestration (e.g.

deserts) Does not necessarily require fresh water

Biomass to Liquids (BTL)via GasificationBiomass to Liquids (BTL)via Gasification

Solid or solid/liquid biomass is converted to gas at high temperatures in the presence of small amounts of oxygen

Main objective is to transfer the maximum amount of chemical energy within the feedstock to the gaseous fraction by producing a high yield of low molecular weight products (high H:C)

The resulting gas is “conditioned” to produce synthesis gas (syngas)

Syngas is then converted to liquid fuel via the Fischer-Tropsch process

High-Productivity FeedstocksHigh-Productivity Feedstocks

Corn grain Sweet sorghum Energy cane

3.4

20

30

Pro

duct

ivit

y

Dry

tons

/(ac

re·y

r)

Sweet SorghumSweet Sorghum

Grows in ~35 US states

Energy Cane

Energy Cane

High Agricultural IncomeHigh Agricultural Income

Corn grain Sweet sorghum Energy cane ($2.40/bu) ($40/tonne) ($40/tonne)

340

730

1090

Gro

ss I

ncom

e

$/(a

cre·

yr)

Low Environmental ImpactLow Environmental Impact

WaterFertilizerPesticidesHerbicidesSoil erosion

Corn Sweet EnergyGrain Sorghum Cane

High Low Low High Low Low High Low Low High Low Low High Low Low

Environmental cost perunit of biomass

Ideal Process Properties Ideal Process Properties

No sterilityNo genetically modified organisms (GMOs)AdaptableNo pure culturesLow capitalNo enzymesHigh product yieldsNo vitamin addition Co-products not required

Fuel PropertiesFuel Properties

Ethanol MTBE Mixed Alcohols

Octane high high high

Volatility high low low

Pipeline shipping no yes yes

Energy content low high high

Heat of vaporization high low low

Ground water damage no yes no

MixAlco ProcessMixAlco Process

Ferment DewaterDewaterPretreatPretreat ThermalThermalConversionConversion HydrogenateHydrogenate

Lime KilnLime Kiln

MixedMixedAlcoholAlcoholFuelsFuels

MixedMixedKetonesKetones

BiomassBiomass

HydrogenHydrogenCalcium CarbonateCalcium Carbonate

LimeLime

CarboxylateSalts

Storage + Pretreatment + Fermentation

Storage + Pretreatment + Fermentation

Biomass + Lime + Calcium Carbonate

Gravel

Air

Tarp Cover

DewateringDewatering

FermentFerment DewaterPretreatPretreat ThermalThermalConversionConversion HydrogenateHydrogenate

Lime KilnLime Kiln

MixedMixedAlcoholAlcoholFuelsFuels

MixedMixedKetonesKetones

BiomassBiomass

HydrogenHydrogenCalcium CarbonateCalcium Carbonate

LimeLime

CarboxylateSalts

Vapor-Compression DewateringVapor-Compression Dewatering

SaltSolution(Fermentor Broth)

Distilled Water

Filter

Salt Crystals

Compressor

Work

Effect of Feedstock Cost (800 tonne/h, 15% ROI) Effect of Feedstock Cost (800 tonne/h, 15% ROI)

-40 -20 0 20 40 Biomass Cost ($/tonne)

1.00

0.80

0.60

0.40

0.20

0.00

Alc

ohol

Sel

ling

Pri

ce (

$/ga

l)

Centralized ProcessingCentralized Processing

15.3 mi

50% of area planted

How do we increase engine efficiency?How do we increase engine efficiency?

• Electric hybrids (2 Electric hybrids (2 XX))• Better engines (2– 4 Better engines (2– 4 XX))

Meeting US gasoline needs by growing energy cane in BrazilMeeting US gasoline needs by growing energy cane in Brazil

1 × 2 × 3 ×

Meeting US gasoline needs by growing sweet sorghum in United StatesMeeting US gasoline needs by growing sweet sorghum in United States

1× 2× 3×

ConclusionConclusion

• Reduce wastesReduce wastes• Cleaner airCleaner air• New agricultural marketsNew agricultural markets• Energy securityEnergy security• Improve balance of paymentsImprove balance of payments• Address global warmingAddress global warming• Address energy shortageAddress energy shortage• More flexible international relationsMore flexible international relations• Benefit developing nationsBenefit developing nations