Biofuels: Optimism and Concerns - Desert Research Institute

Biofuels:
Optimism and Concerns
2008 MIT/NESCAUM
Symposium on Urban Transportation
Endicott House
Dedham, Massachusetts
August 13, 2008
S. Kent Hoekman, Ph.D.
Desert Research Institute
Division of Atmospheric Sciences
Kent.Hoekman@dri.edu

Outline
1. Background on U.S. Energy Usage
2. Policy and Regulatory Drivers for Biofuels
3. Feedstocks for Biofuels
4. Biomass Conversion Technologies
5. Environmental Considerations
6. Promoting Responsible Growth of Biofuels
7. Summary and Conclusions
2

Historical Energy Use in the U.S.
(Years 1775 – 2005)
Current use of every primary energy source is greater now
than at any previous time in U.S. history
Source: http://www.eia.doe.gov/emeu/aer/pdf/aer.pdf
3

Recent and Future U.S. Energy Production
(Years 1980 – 2030)
Source: EIA Annual Energy Outlook 2008
4

Quads
U.S. Renewable Energy
(2006; with projections to 2030)
In 2006, about 6.3% of total U.S. energy consumption came from
renewables (including hydroelectric).
14
12
10
8
6
4
2
0
2006
2030
Source: DOE-EIA; Annual Energy Outlook 2008
Biomass Energy
Municipal Waste
Residential Wood
Wind
Solar
Geothermal
Hydroelectric
Other Trans Fuels
Biodiesel
Ethanol
Current annual gasoline consumption is about 140 billion gallons –
equivalent to 17.6 Quads
5

Drivers for Biofuels in the U.S.
• “America is addicted to oil.”
– President G. W. Bush; January 2006
• Federal Executive Actions:
– Advanced Energy Initiative (AEI) (2006)
– 20-in-10 Plan (2007)
• Federal Legislative Actions:
– Energy Policy Act of 2005
– Energy Independence and Security Act
of 2007
• State Actions:
– California Low Carbon Fuel Standard
– California AB-32 (GHG reduction)
State of the Union
Address (1/31/07)
6

Benefits and Challenges of Biofuels
Improved Energy
Security
• Increased domestic
supply
• Widely distributed
resources
• Greater supply
reliability
• Petroleum reduction
Economic
Productivity
• Price stability
• Increased rural
development
• Reduced trade
deficit
• Improved global
competitiveness
Environmental
And Other
Impacts
• GHG impacts
• Carbon
sequestration
• Land and water use
• Wildlife habitat
• Biodiversity
• Food resources
7

Terminology for Liquid Transportation Fuels
(Common terms, but not universally accepted)
1. Conventional Fuels: produced from petroleum
2. Alternative Fuels: produced from non-petroleum sources,
including other fossil sources (coal, natural gas)
3. Renewable Fuels: produced from modern biological precursors
(plants and animals)
4. Biofuels: synonymous with “Renewable Fuels”
5. 2 nd Generation Biofuels: Biofuels produced from non-food
feedstocks – especially lignocellulose
6. Biodiesel: methyl esters produced from fats and oils
7. Renewable Diesel: non-fossil hydrocarbon fuel produced via
hydroprocessing of fats and oils
8. Cellulosic Fuels: produced via biochemical or thermochemical
conversion of lignocellulosic materials
9. Clean Fuels: ??
8

Rapid Growth of Biofuels in the U.S.
• Currently dominated by corn-based
ethanol
– 6.4 billion gallons in 2007
– Supplies about 4% of U.S. gasoline
demand
– Requires about 15% of U.S. corn crop
• Biodiesel is growing, but still small
– 0.45 billion gallons in 2007
– Supplies ~1% of U.S. diesel demand
– Main feedstocks:
• U.S. – soy oil and waste oils
• Europe – rapeseed oil
9

Billion Gallons/Year
2005
Energy Act
2007 Energy Act
U.S. Renewable Fuels Production
and Volume Requirements, bg/y
36
32
Production Volumes
Energy Act Requirements
28
24
Cellulosic
Ethanol
20
16
Other Renewables
Biodiesel
12
8
4
Ethanol
Biodiesel
Corn Ethanol
Corn Ethanol
0
Year
36 bg/y represents about 25% of current gasoline volume
10

Biomass Resource Base in U.S.
Primary
Secondary
Tertiary
Forest Resources
• Logging residues
• Forest fuel treatment
• Fuel wood
• Mill residues
• Pulping liquors
• Wood processing residues
• Construction debris
• Demolition debris
• Urban tree trimmings
• Packaging waste
Agricultural Resources
• Crop residues
• Grain
• Perennial grasses
• Woody crops
• Animal manures
• Food/feed processing
residues
• Municipal solid waste
(MSW)
• Landfill gases
11

U.S. Forest Biomass Resources,
million dry tons/year (mdt/y)
Source: DOE/USDA, The Technical Feasibility of a Billion-Ton Annual Supply
(April 2005)
12

Potential U.S. Agricultural Biomass
Resources (mdt/y)
Source: DOE/USDA, The Technical Feasibility of a Billion-Ton Annual Supply (April 2005)
13

Major Biofuels Production Pathways
Feedstock Process Main Fuel Products
Starch, Sugar
Corn, sugar cane,
sorghum, etc.
Lignocellulose
Wood waste
Grasses
Trees
Ag. waste
Triglycerides
Vegetable oils
Animal fats
Algal lipids
Hydrolysis/
Fermentation
Biochemical
Pretreatment
Enzymatic Hydrolysis
Fermentation
Thermochemical
gasification
pyrolysis
Transesterification
Hydroprocessing
Ethanol
Ethanol
Alcohols,
Hydrocarbons
Fatty Acid Methyl
Esters (Biodiesel)
Hydrocarbons
(Renewable Diesel)
14

DOE’s Integrated Biorefinery Concept
Source: NREL (2006)
15

Environmental Concerns with Biofuels
• Water quantity and quality
• Runoff of nutrients and
agricultural chemicals
• Long-term impacts of crop
residue removal
• Disruption of habitat
• Effects on biodiversity
• Sustainability of agricultural
and forestry practices
For ecologic dimensions of biofuels, see links at:
www.esa.org/science_resources/biofuelsResources.php
16

Life-Cycle Impacts of Biofuels
Many different life-cycle assessments
(LCA) have been conducted by many
different researchers.
Very controversial area. Results
depend upon assumptions about:
‣ Allocations of energy and GHGs to coproducts
‣ Agricultural practices and resulting GHG
emission rates (especially N 2 O)
‣ Type and extent of fossil energy used in
life-cycle
‣ Land use changes: CO 2 debt created
by land clearing and new cultivation
17

Many LCA Studies Conducted for Ethanol
• Recent model developed by
Ferrell et al. to harmonize
assumptions used in many LCA
studies.
• In general, results show:
- Small energy and GHG benefits
from corn-derived ethanol
- Large benefits from cellulosic
ethanol
• Limitation: study considers only
direct effects, not indirect effects
due to land use changes
Source: Farrell et al, Science, 311, 506-508 (2006)
18

General Observations Regarding LCA of Biofuels
• Importance of indirect effects is now recognized
– No consensus on how to quantify these effects
– No consensus on how (or if) to incorporate into policy
• LCA results are highly scenario specific – very difficult to
generalize for a particular biofuel
• 2 nd generation biofuels are clearly preferred over 1 st
generation biofuels
• Recent publications of interest:
- R.Hammerschlag, Environ. Sci. Technol. 40, 1744-1750 (2006)
- E.A.Farrell et al., Science, 311, 506-508 (2006)
- J.P.W.Scharlemann and W.F.Laurance, Science 319, 43-44 (2008)
- J.Fergione et al., Science 319, 1235-1238 (2008)
- T.Searchinger et al. Science 319, 1238-1240 (2008)
19

Promoting Responsible Growth of Biofuels (1 of 4)
1. Avoid “One-Size-Fits-All” Approach
– Maximize usage of local/regional biomass resources
– Minimize transportation of feedstocks
– Expand diversity of feedstocks, processes, and products
– There is no single best technology
• Match technology with available feedstock
• Integrate technologies – biorefinery concept
20

Promoting Responsible Growth of Biofuels (2 of 4)
2. Emphasize Sustainability of Biofuels
– Life-cycle assessments (LCA) are very important
• Must be improved/expanded
• Consider both direct and indirect effects
• Consider energy, GHG, environ., and ecological impacts
• Develop common metrics that accurately reflect true impacts
– Minimize tradeoff between food and fuel. Consider 1 st
generation biofuels as temporary transition to 2 nd generation
– Economic sustainability is also important
Source: CEC Report 600-2007-004-Rev., August 2007
21

Promoting Responsible Growth of Biofuels (3 of 4)
3. Promote Consumer Acceptance
– Demand high fuel quality
• At refinery gate, and in marketplace
• Develop and enforce product specifications
– Maximize use of existing infrastructure
• Refining, blending, storage, distribution, marketing
• Minimize changes for consumer
– Ensure acceptable cost, availability, convenience, and
performance of products
22

Promoting Responsible Growth of Biofuels (4 of 4)
4. Integrate Biomass-to-Biofuels Supply Chain
– All steps in supply chain are important
– Entire chain must be economically sustainable
Source: DOE Biomass Multi-Year Program Plan (2007)
23

Summary and Conclusions (1 of 2)
1. 2 nd Generation biofuels can
play an important role in
stabilizing GHGs and
reducing petroleum
dependency.
2. Biofuels industry is
currently undergoing rapid
transformation and growth.
• Many biochemical and
thermochemical
technologies are being
explored
• No single “best approach”
is likely to emerge
Source: http://celebrating200years.noaa.gov
24

Summary and Conclusions (2 of 2)
3. U.S. has abundant natural resources to support
production of 2nd generation biofuels sufficient to
displace 30-40% of conventional fuels.
4. Sustainable implementation of biofuels requires:
• Careful attention to adverse impacts on natural resources,
environment, and ecology
• Development of common metrics and methods for assessing
life-cycle impacts
5. For widespread consumer acceptance, biofuels must
be conveniently available, affordable, and compatible
with conventional fuel/vehicle systems.
25

Thank You!