Challenges in Renewable Biofuel Productionilp.mit.edu/images/conferences/2012/EURO/23 -...
Transcript of Challenges in Renewable Biofuel Productionilp.mit.edu/images/conferences/2012/EURO/23 -...
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
2012 MIT-Europe Energy Conference
Rome
March 28-29, 2012
Challenges in Renewable Biofuel Production
Gregory Stephanopoulos MIT
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Types of biofuels and biofuel feedstocks
Ethanol from corn Biodiesel from plant seeds and vegetable oils
Ethanol from sugarcane Other feedstocks (not competing with food):
cellulosics, algae, synthesis gas Other biofuels than ethanol (butanol, lipids,
hydrocarbons)
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Examples of advanced biofuels
Other higher alcohols: butanol, isobutanol, propanol, pentanol, … Longer, branched alcohols (3-Methyl-1-Butanol) Hydrocarbons of any type Oils (C16, C18) Methyl, ethyl esters of fatty acids (FAME=biodiesel) Isoprenoid pathway products: Isopentenol, farnesene Jet fuel Isooctane
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Difference between Ethanol and all the others
We can make ethanol
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Bio-fuels: Primarily a feedstock story
Produced either from
• Biomass, or, • Any feedstock by biological methods
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Summary of the state-of-the-art in biofuel development
(in 4 slides)
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
1. Sugar platform
Starches (Corn) Sugarcane
Hydrolysates of plentiful biomass-algae
Sugars Ethanol
Advanced biofuels
Easy conversion
Biomass deconstruction still challenging
Straightforward with yeast
Requires Metabolic Engineering
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Plentiful Biomass?
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
How much biomass is there?
BTS (DOE): 1.37 billion tons/year NAE-NRC study on Alternative Fuels:
Feedstock type Current amount By 2020 (million tons)
Corn stover 76 112 Wheat and grass straw 15 18 Hay 15 18 Total cropland biomass 106 148 Dedicated biofuel crops 102 164 Woody biomass 110 137 Paper and paperboard 10 20 Animal manure 6 12 Municipal solid waste 90 120 TOTAL 424 601
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Potential of biofuels (USA)
70-100 gallons ethanol/dry ton of biomass 42-60 B gallons Ethanol/year or 28-40 B gallons of gasoline equivalent 20-30% of gasoline used
Potential is greater when advanced biofuels are produced such as biobutanol or biodielsel
(1 ton of ethanol = 333 gallons, or 1 Gallon = 3 kgs, or 1 B Gallons = 3 M tons)
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Sophisticated pathway and microbe engineering is required to create biocatalysts for converting
sugars to advanced biofuels
Coupled with
Advanced bioprocessing (isobutanol)
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Pentanol Synthesis
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Challenges: 1. Supply of building block
(Propionyl-‐CoA) 2. Condensa?on reac?on of
C2 + C3 3. Acceptance of 5-‐carbon
substrates for the rest of pathway enzymes
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012 13
Thiolase
Dehydrogenase &
Dehydratase Mutase Reductase
Biofuels toolkit
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012 14
Biofuels toolkit
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012 15
Advanced metabolic engineering
Allows biosynthesis in microbes of almost any fuel or chemical,
natural or not
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Cells: Little chemical factories with thousands of
chemical compounds interconverted
through thousands of chemical reactions
Main substrate: Sugars
Products: Virtually
infinite
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Redirecting Carbon Flux
Rxn
1
Rxn
3
Rxn
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Rxn
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Rxn
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Rxn
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Pentanol
Substrates ?P 2 P 4
P 4
18
CoA activator
CoA remover
HPLC analysis
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
2. Biofuel production by direct photosynthesis
Algae
Sun
Biomass
Oil-alkane production
Other biofuels (ethanol)
Productivities are high but cultures very dilute
Key challenge: Cost-effective dewatering
Just growth
Metabolic Engineering; Secretion?
Oil recovery
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Algae
Gallons GE/acre/year Soybeans 48 Sesame 74 Jatropha 202 (50?) Cellulosic ethanol 533 Sugarcane ethanol 566 Algae ~6,000
However, to produce 1 gallon of oil one must move around ~2,000 gallons or water
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
3. Biodiesel
Oils Biodiesel (FAME)
Simple trans-esterification reaction Key issues: Feedstock cost and availability
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
3. Biodiesel
Key points: It is a bad idea to use vegetable oils for biodiesel Sustainable biodiesel production MUST be based
on carbohydrates Gallons GE/acre/year Soybeans 48 Sesame 74 Jatropha 202 Cellulosic ethanol 533 Sugarcane ethanol 566 Algae ~6,000
Need organisms capable of converting sugars to fats and lipids (or Free Fatty Acids, FFA)
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Wild type
Recombinant Some results on recombinant oil producing microbe
Total sugar consumed: 312 g/L Total oil produced: 80g/L in 72 hours Yield: 29.4% Theoretical Maximum Yield: 31%
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FAM
E (g
/l)
Lipid production
Patent pending
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
A tripod of feedstock and products
Feedstock: Glucose/sugar
(1 kg)
Product: Ethanol
(~0.51 kg)
Product: Fats/Oils (0.31 kg)
Amounts of two products are energetically equivalent (possible due to the almost theoretical yield of our microbe)
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Electrofuels
(They can increase the yield of solar energy conversion by an order of magnitude relatively
to photosynthetic systems)
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
The “Electrofuels” FOA was released in Dec. 2009 in response to a need for more efficient biofuel production technologies
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Photosynthesis
Biomass
EtOH, Advanced biofuels
Algae
Pyrolysis oils
Biodiesel, Advanced biofuels
Electrons/ Reducing equivalents
Syngas, CH3OH, CH4,
Advanced fuels?
Chemical Catalysis Biological
Catalysis
Advanced Fuels
Electrofuels
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Bio-GTL
Goal: Produce an infrastructure compatible fuel (biodiesel) from CO2 and CO/H2 Asset: Oleaginous microbe with extremely high yields, productivities, and titers Strategy: Fix CO2 with CO/H2 in acetogenic bacteria or Clostridia and/or via rMFC and feed acetate so produced to Oleaginous microbe Challenges: Achieve high rates of growth of acetogenic bacteria, and acetate produc’n
Ana
erob
ic C
O2
redu
ctio
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H2OSplit
O2
H2
Aerobic oil production from CO2product
OIL
Product of CO2 fixation
NewCO2Recycled CO2
Ana
erob
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O2
redu
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H2OSplit
O2
H2
Aerobic oil production from CO2product
OIL
Product of CO2 fixation
NewCO2Recycled CO2
Ana
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O2
redu
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naer
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CO
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H2OSplit
O2
H2
H2OSplitH2OSplit
O2
H2
Aerobic oil production from CO2product
OIL
Aerobic oil production from CO2product
OIL
Product of CO2 fixationProduct of CO2 fixation
NewCO2Recycled CO2
NewCO2Recycled CO2
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Supporting Evidence
Growth and acetate production of Acetobacterium woodii on fructose and H2/CO2
Preliminary Calculations: Acetate Productivity: 2.4 g/
L/day (0.1 g/L/h) 0.274 g oil/g acetate 3.33 Kg OIL/Gal ~170 Million gals of
fermentor capacity required for a 50Mgal/year oil plant
O.D. 25-30x lower of a typical EtOH fermentation
Specific rate g/g/hour comparable to ethanol
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Main Challenges
Main Challenge 1: Improve oil production from acetate: 20-30 g/L at yields greater than 80% of theoretical maximum and productivities of 0.6-1.0 g/L/h
Main Challenge 2: Increase Volumetric Productivity of acetate production by ~ 15 fold
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
4. Bio-GTL
Natural gas Steel mills
Gasification of biomass, MSW, coal
SynGas
Ethanol
Advanced biofuels
Expensive gasifiers
Clostridia (Koskata, AlzaTech)
Acetate
Acetogens (Moorella)
OIL
via Metabolic Engineering
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
CO2
Acetyl-CoA Metabolic pathway
2e -
2e - 2e -
2H+ + 2e -
Acetyl CoA
Acetic Acid Ethanol
2e -
2e -
Met
hyl B
ranc
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Car
bony
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Acetyl - PO32-
ATP
Acetaldehyde
Hydrogenase
CODH 2e -
Acetyl-CoA Synthase
ATP
CO2
CO
H2
2e -
Isobutanol and other biofuels
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Electron production
2 CO2 + 8 e- C2H4O2
Acetyl-CoA pathway
H2 2 H+ + 2 e-1
CO + H2O CO2 + 2 H+ + 2 e-1
hydrogenase
CODH
If electrons from H2
2 CO2 + 4 H2 C2H4O2 + 2 H2O If electrons from CO
4 CO + 2 H2O C2H4O2 + 2 CO2
4 moles needed
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Gas fermentation challenge: solubility
Species C* (mM) CO2 48 CO 1.2 H2 0.83
@T=37 0C, P=1 atm.
Strategies: 1. Closed bioreactor: High pressure 2. Continuous-gas bioreactor: High mass transfer rate
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Summary of kLa
Reactor Diffuser Agitation (rmp) kLa (1/hr) Stirred tube 100 1.74
Column tube NA 13.2 Column Micro bubble NA 25.8
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
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Tota
l Car
bon
(g/l)
Time (hr)
Carbon utilized-exp 2 CO availability-exp 2
CO2 availability
Carbon utilization: Experiment 1
Utilization = 0.5×cell mass + 0.4×Cacetate
(g/l)
Availability of Gas = 12×kLa×C* (g/l/hr)
)( *tLA CCakN −=
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
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Carbon utilized-exp 1 Carbon utilized-exp 2 CO availability-exp 1 CO availability-exp 2 CO2 availability
Carbon utilization: Experiments 2,3
Gas fermentation is limited by CO availability 4 CO + 2 H2O C2H4O2 + 2 CO2
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Experimental summary-Acetogens
Feedstock Acetate (g/l) Productivity (g/l-hr) CO2, CO, H2 25 0.13
CO2, CO 29 0.18 CO 30 0.40
Glucose, Syngas 21 0.39 Glucose, CO2 26 0.42
Electron donors: H2, CO, glucose Electron acceptor: CO2
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
The future of biofuels: Take away points
1. Corn ethanol will max out at ~15B Gallons/year 2. Biomass supply: Sufficient for 25-40 B GGE without stressing
the food supply 3. Cellulosic ethanol: Slow in coming. Several plants under
deployment 4. Cellulosic ethanol: Interplay of biomass deconstruction
technologies and cost of biomass 5. Cellulosic ethanol: Negative interaction between supply chain
development and technology development 6. Butanol: Will do well if the E10 wall is maintained. Main
advantage seems to be low volatiles
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
The future of biofuels: Take away points (cont’d)
7. Drop-in biofuels: Unnecessary. Aim for maximum cost-effectiveness
8. Algae: Were promoted on the basis of productivity and not-land based. Key is cost-effective dewatering technologies
9. Great need: High density biodiesel and jet fuel 10. Biodiesel: Production from oils and vegetable seeds is costly
and unacceptable environmentally 11. Great promise: Technologies for converting renewable
feedstocks (sugars, biomass) to oil 12. Novel Bio-GTL technologies are promising
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
The end
Questions?
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
• Co-products Marketing such compounds
as, higher-priced, chemicals
u Summary: Bio-GTL technology
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Consider: Yields (gallons ethanol/kg sugar) is most important metric for economical process Ethanol is produced at almost maximum theoretical yield Ethanol has low energy density, i.e., very low cost per volume
What is the likelihood that one of the advanced biofuels will compete
successfully with ethanol?
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Some calculations
1 Gallon of biodiesel = 3.8 Liters = 3.4 Kgs can be produced from 3.4 / 0.31 = 11 Kgs of Glucose that costs ~ $1.20-1.40 • Hence, biodiesel can be produced from sugars at an estimated total cost of $1.80-2.00 • Probably less with other feedstocks that have potential for drastically lower cost
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
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2L fermenter
YL-‐Eng-‐OD
YL-‐Wild-‐OD
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
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CB+Hemo+Glut1 D9+CB+Hemo+Glut1
TAG/
Sugar g
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Mutant strains
2L bioreactor with C5 Hz with 200g/l sugars
TAG
Sugar consumed
Mutant1 Mutant2
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
72 hour fermentation. C5 Xz supplemented with 200g/L of glucose. Yield for mutant 3 is 41/155 = 26.5%
Mutant 2 Mutant 1 Mutant 3
41
155
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Some calculations with corn ethanol
~10.6 B gallons of ethanol estimated produced in US from corn in 2009 [at current production]
This is equivalent to ~8 B gallons gasoline It takes 0.75-0.85 units of fossil energy to
produce 1 unit of energy in fuel ethanol
The 10.6 B gallons of ethanol displace ~2 B gallons of petroleum, or ~1.5% of US needs
It takes >30% of the US corn production to produce the 10.6 B gallons of ethanol
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Where is this biomass?
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
• 1.1 Billion tons mined per year • Gillette Coal field (Wyoming): 80 miles strip with 10 top-producing mines. 1.2 million tons daily (1/3 of US total) leave the field daily, a river of coal filling more than 75 trains with 150 cars each • American Electric Power (AEP) has 9,100 cars and 2,480 river barges dedicated to supplying its power plants with coal
Coal does not come easy
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Biorefineries are geographically confined
51 51 MIT
Oil refinery BioRefinery
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
BR D=60 miles
S
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Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
Economics
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
-‐$20
$0
$20
$40
$60
$80
$100
$120
$140
$160
$180
$200Per Barrel Cost Oil Equivalent Product Prices
CO2 cost (ignoring indirect CO2 consequences) Carbon Storage CostAdditional Transportation Cost Non-‐Feedstock Oper CstCapital Cost Feedstock Cost
Greg Stephanopoulos MIT-Europe Energy Conference March 28, 29, 2012
-‐ $60 -‐ $40 -‐ $20 $0
$20 $40 $60 $80
$100 $120 $140 $160 $180 $200 Per Barrel Cost Oil Equivalent Product Prices
CO2 cost (ignoring indirect CO2 consequences) Carbon Storage Cost Addi?onal Transporta?on Cost Non -‐ Feedstock Oper Cst Capital Cost Feedstock Cost
Cost of fuels produced from biomass (B), coal (C), or combined coal and biomass (CB) using biochemical conversion (that is corn ethanol or cellulosic ethanol) or thermochemical conversion via Fischer-Tropsch (FT) or MTG with a carbon tax of $50 per tonne CO2 added. For
thermochemical conversion, FT and MTG with or without carbon capture and sequestration (CCS)