Alfalfa Alfalfa & Switchgrass Switchgrassas as Biofuels: Biofuels: Possibilities Possibilities and and Limits Limits Dan Putnam University of California, Davis
Why Why Biofuels? Biofuels? World Demand for petrochemicals America 1/3 of world autos, uses 25% of the worlds oil Last 10 years +2 Americums (350 m people >$15,000/yr) New Americum developing every decade or so Climate Change (one-way carbon street) the grand experiment Fuel Security, self-sufficiency, sufficiency, economics Petro-dictators Biofuels - One of many alternatives Including conservation
Types Types of of Biofuels Biofuels Grain Biofuel Crops (starch to ethanol) Biodiesel Crops (esterification( of oils) Sugar Ethanol Crops (sugar to ethanol) Cellulosic Energy Crops (cellulose to ethanol or combustion)
Grain Grain to to Ethanol Ethanol Starchy Grain Crops Starch-enzymatically broken to glucose Fermentation of sugars to alcohol Fermentation, distillation (requires energy) Key Issues: Competition with food/feed grains Energy Balance (0.8 to 1.6 yields of Fossil Fuel input to fossil fuel
Plant Plant oils oils to to Diesel Diesel Biodiesel Crops Oilseeds (canola, soybean, camelina) Waste vegetable and animal oils Key Issues: Simplicity - scalable Cost/resource inputs Yields/percent oil Competition with edible oils Energy Balance Camelina sativa
Sugar crops Sugar Sugar to to Ethanol Ethanol Sugarbeets,, sugarcane, sweet sorghum Key Issues: Highly productive Direct Fermentation/Simplicity Bulky Materials (transport) Concentrated processing Transient product (timeliness)
Cellulose Cellulose to to Ethanol Ethanol Cellulosic crops Wood, wastes, straws/stovers, stovers, cellulosic crops Key Issues: High yields Bulky Materials Transportation/Storage Conversion technology limiting Pretreatment requirements Enzymatic conversion technology
Soybea n Esterificati on Energy Energy Conversions: Conversions: Extract Oil Cor n Starch Enzymes Glucose Fermentati on Distillation Sugarcane Extraction Fermentati on Switchgras s Pre-Treatment Enzymes Glucose Fermentati on Biodiesel Ethanol Ethan ol Ethan ol
Govt. Govt. Impetus: Impetus: 2007 Bush proposed: 20 in 10 Reduce petroleum-based gasoline use by 20% in 10 years 35 billion gallons/yr by 2017 Congress: renewable fuel standards: 2022 2008 Farm Bill - $1 billion on biofuels. 2008 Implementation Plan: Sustainability Food, environmental, economic Cellulosic biofuels important
US US DOE DOE Biofuels BiofuelsInitiative Assumptions (DOE biofuels goals) Modest growth in ethanol production from grain Double current production >80% of growth in ethanol is from cellulosic fermentation Forestry and wood byproducts Crop residues Perennial energy crops
DOE Billion Ton Vision - 2006 Summary of potential forage and agricultural biofuel resources Forestry and residues Grain to ethanol Process residues Perennial crops Crop residues Alfalfa/Switchgrass fits here One billion tons of agricultural biofuels potential 0 100 200 300 400 500 DM Tons/yr (millions) It will take a collection of regionally adapted biofuel crops to hit these targets.
Feedstocks Feedstocks (DOE, (DOE, Oct. Oct. 2008) 2008) First Generation (current): Corn ethanol Soybean/canola biodiesel Second Generation Crop residues, stovers,, municipal and forest wastes Need improved cellulosic conversion technology Third Generation: Dedicated Energy Crops (perennial grasses, alfalfa) Fast Growing Dedicated Tree Crops Algae
Cellulosic CellulosicFeedstocks Little doubt that wastes will be prime first candidates Landfills (30-40% paper) Tree/forestry by-products Straws & stovers (wheat, barley, corn) Dedicated Feedstocks Fast Growing trees, switchgrass, Miscanthus,, annuals (grains, sorghums), alfalfa
Criteria Criteria to to Choose Choose Cellulosic Feedstocks: Don t t Start with the answer! Keep asking the question! Likely to be multiple answers
Criteria Criteria to to choose choose Feedstocks Feedstocks High Biomass Yields. Reduce the cropping area Efficiency of resource use High rates of conversion of solar to stored plant energy Yield per unit resource Genetic/Systems innovations
Criteria Criteria to to choose choose Feedstocks Feedstocks Quality of Conversion. Not all cellulosic materials can be converted into biofuel with the same efficiency Ethanol yield per unit weight crop Conversion is affected by species, N, maturity, irrigation, fertility Enzymatic recipe
Criteria Criteria Water Use Efficiency THE critical issue for CA EFFICIENCY is one issue (max. DM per unit water) FLEXIBILITY of water use may be as important Coping with water deficits (yields OK under both high and low water situations) Using Saline water/degraded water sources sources
Criteria Criteria for for selection selection of of Biofuels Biofuels Yield 12 10 8 6 4 2 0 species 1 species 2 Species for waterlimited enviornments 0 2 4 6 8 10 12 Applied water Species for sufficient water-use regions
Irrigated Irrigated Biofuels???? Biofuels???? CA-$37 billion food-producing powerhouse A non-starter? Not necessarily Key advantages Stability of production Very high yield potential Key negatives: Competition with food production
Criteria Criteria Nitrogen Fertilizer Requirement. N requirement is a major limiting factor due to its high fossil-fuel fuel footprint and significant economic impact, influencing conversion and emissions. Impact on food grains
Why Why is is N fertilizer fertilizer so so high high priced? priced? It requires Fossil Fuels! Nitrogen (atm) + Natural gas Approx 32 mcf Natural gas Anhydrous Ammonia 1 ton of Ammonia
Criteria Criteria Impact upon food production. Candidate species which has less impact upon food production may be favored, Competition for land, water Secondary Impacts (fertilizers) Remember: All crops will compete to some degree Integration with food production
Criteria Criteria Utilization of waste/resource efficiency Species adapted to wastewater, salty conditions, marginal land or utilize resources which are not otherwised used may be favored. The marginal lands model (switchgrass, Miscanthus)
Criteria Criteria Management of Biological Risk. Species which have high resistance to stress, pathogens, pests, and weeds, or compacted situations would be favored. Invasive Species create problems: Arundo donax Johnsongrass Switchgrass?? (listed as a Class B invasive, but not clearly a risk)
Criteria Criteria Infrastructure Support. A developed seed industry, approved chemicals, commercially-available available equipment, and University research data will have early advantages for production.
Criteria Criteria Ecosystem Services. Species which can be demonstrated to sequester additional soil carbon, reduce air pollution potential, conserve soil, water, or other resources, and provide wildlife habitat will be favored.
Criteria Criteria Multiple Use Scenarios Most successful crops have mulitple markets (e.g. soy used for protein, oil) Grain, Stover of grains Sugar, alcohol, bagass (burning) Forages/cellulosic crops Tremendous demand for forages can we envision combination forage-cellulosic biofuel systems?
Multiple Multiple uses uses of of bulky bulky Biomass Biomass Crops Crops Fulfills two purposes: Creates a forage product of higher quality Two income streams Isolates N-containing N compounds from cellulosic Two scenarios: Via cutting Schedule (1 cut-forage, 1 cut biomass) Post-harvest Separation of leaf stem Field Separation? ( In-field field separation?
Can Can we we envision? envision? $120/ton Coarse forage (12 tons) $170/ton high quality $80/ton high quality Fraction (6 tons) Fraction (6 tons)
feet 0 2 4 6 8 10 12 14 16 18 Advantages of of perennial perennial crops crops Alfalfa High yield Use full growing season Reduced runoff Reduced nutrient losses Reduced soil erosion Deep and extensive root system Efficient water use Improved soil tilth Carbon sequestration Image courtesy of Mike Russelle
Alfalfa as as a potential energy crop crop DOE Photo
An Alfalfa Biomass System N 2 Alfalfa CO 2 Manure UCD Leaves Stems Soil Ash
N Advantage Advantage of of Alfalfa Alfalfa Estimate that to replace the protein produced each year by 1 million acreas of alfalfa in CA would require 5 million acres of corn. Trillions of BTUs fossil fuel savings A Key issue for biofuels!
Compatibility Compatibility with with corn corn Tim McCabe, NRCS Nitrogen credit Residue cover Erosion control Aesthetics Wildlife habitat Don Reicosky, USDA-ARS
Symbiotic Symbiotic N 2 fixation 2 fixation Sinorhizobium Dazzo & Wopereis, 2000 Root hair curling around rhizobia Bacteria reproduce in infection threads Vance et al., 1980 Alfalfa root nodule Bacteroids filling a single cell Dazzo & Wopereis, 2000 Gage and Margolin, 2000 M. Barnett
One-pass separation of leaves and stems is feasible M. Russelle, USDA-ARS 90% leaves 27% protein 20% fiber 90% stems 13% protein 50% fiber Shinners & Digman U Wisc and USDFRC
Alfalfa: Alfalfa: Genetic advances Breakdown of cellulose Downregulated lignin
New alfalfa biomass management system (MN w > Biomass type alfalfa (reduce lodging, increase yield) > Thinner stand (60% less seed, save $ and energy) > Harvest less frequently (save $ and fuel) Total Yield (Tons/Acre) 8 6 4 2 0 Hay 40% Higher Yield Biomass Double Ethanol Yield Production System Hay Biomass 0 400 300 200 100 Theoretical Ethanol Yield (Gal/Acre) Lamb et al., 2007
Yield(t/ha) 30 25 20 15 10 5 0 Late Late Cutting Cutting Schedules: Schedules: 4.0% 20.9% 23.4% 51.7% 2003 8 Cut 7 Cut 5 Cut % of Yield in each quality category 4.7% 31.9% 43.0% 8.3% 12.1% 22.6% 38.1% 14.8% 14.2% 10.3% Early Mid Late Cutting Schedule Quality Category: ADF%: >35 32-35 29-32 27-29 <27 Low Quality High Quality 2 ton/ acre yield Advantag e Late Cutting (Davis)
Theoretical Yields Improved Cropping Systems Ethanol Species Corn Alternate Total Protein Gal/Acre Tons/Acre Continuous Corn Grain (5% yield loss) 616 0 616 0.32 Corn/Soybean (alternate years) 324 40 364 0.38 Corn Silage/Improved Alfalfa (5% yield boost) 780 138 918 0.42
Theoretical Theoretical Program: Program: Alfalfa Alfalfa 10-12 12 ton irrigated yields Late cutting schedules Improved Varieties Low densities, other techniques 4-5 5 tons/acre high value leafy product 5-6 6 tons/acre stemmy cellulosic product
Switchgrass
Switchgrass SwitchgrassTrials: 4 locations: Tulelake,, Davis, Fresno, El Centro Summer planting (June-July) July) 10 varieties (N. Great Plains to Texas) Irrigate to est. ET 0 Moderate N applications
Switchgrass Year 1 yields Switchgrass Year 1 yields CALIFORNIA SWITCHGRASS YIELDS - Seeding 2007 YIELD (t/a) 7 6 5 4 3 2 1 0 Planted: 6/24/07 Harvested: 11/8/07 Planted: 6/5/07 Harvested: 11/19/07 Tulelake Davis Five Points El Centro LOCATION Planted: 6/17/07 Harvested: 11/13/07 Exp55 Exp56 Exp58 Exp57 Exp54 Alamo Kanlow Trailblazer Cave in Rock Blackwell Sunburst Planted: 6/19/07 Harvested: 11/26/07
6.0 5.0 4.0 3.0 2.0 1.0 0.0 Switchgrass Switchgrass-- Tulelake Tulelake 2008 2008 Blackwell Cave in Rock Exp58 Kanlow Sunburst Trailblazer Alamo Exp54 Exp56 Exp57 Series1
t/a Switchgrass Switchgrass Davis Davis 2008 2008 10 9 8 7 6 5 4 3 2 1 0 3.0 6.1 1.6 5.4 1.8 5.6 Alamo Blackwell Cave in Rock 2008 Switchgrass Yield by Cut. Davis, CA 2.0 6.8 2.8 6.1 2.9 5.6 2.7 6.3 Exp54 Exp55 Exp56 Exp57 Kanlow Sunburst Trailblazer Variety 1.4 6.8 1.9 5.6 1.3 5.3 30-Oct 18-Jul
Switchgrass Switchgrass Fresno Fresno Co. Co. 2008 2008 20 18 16 14 12 t/a 10 8 6 4 2 0 5.2 6.2 11.2 5.6 9.1 8.8 Alamo Blackwell Cave in Rock 2008 Switchgrass Yield. Five Points, CA 12.4 5.3 5.1 4.7 5.2 4.1 5.3 4.7 19-Nov 23-Jul 12.8 11.9 11.8 12.0 7.8 8.3 Exp54 Exp55 Exp56 Exp57 Kanlow Sunburst Trailblazer Variety
20 18 16 14 12 t/a 10 8 6 4 2 0 2008 2008 Switchgrass Switchgrass El El Centro Centro 2.1 5.0 11.3 1.1 4.0 5.3 1.4 1.4 3.6 3.5 4.9 2008 Switchgrass Yield by Cut. El Centro, CA 1.9 4.7 11.6 2.1 5.0 10.0 2.3 4.8 10.1 2.2 5.0 1.7 4.4 11.8 1.1 9.8 3.3 6.3 2.2 Alamo Blackwell CaveinRock Exp54 Exp55 Exp56 Exp57 Kanlow Sunburst Trailblazer Variety 6-Nov 8-Sep 11-Jul
2008 2008 CA CA Switchgrass Yields Yields YIELD (t/a) 20 18 16 14 12 10 8 6 4 2 0 CALIFORNIA SWITCHGRASS YIELDS - 2008 Season Totals Planted: 6/24/07 Planted: 6/5/07 Planted: 6/17/07 Planted: 6/19/07 Tulelake Davis Five Points El Centro LOCATION Exp55 Exp56 Exp58 Exp57 Exp54 Alamo Kanlow Trailblazer Cave in Rock Blackwell Sunburst 18 t/a 4 t/a
Scenarios: Scenarios: Low Input Scenario: Average 3-6 t/a low imput model (Nebraska Model) Net energy 540% more Fossil Fuel energy than consumed (5x). (Science, 2007)
Scenarios: Scenarios: High Input, Multiple Use Scenario: What about 15 ton yields with 5-75 for forage, and 5-75 7 for biofuels? Lessens Food vs. fuel issue Economic driving forces By definition: irrigated agriculture is not low input Need innovation
Key Key Points Points Biofuels must meet sustainability criteria Economic (!) Environmental Resources Alfalfa & Switchgrass are interesting possibilities: N2 fixation (alfalfa) High-yield/heat adaptation (switchgrass) High Water Use Efficiency Wildlife habitat/environmental services Integration with forage production Longer term Concepts Development of conversion technologies Life-cycle analysis impact on resources We need to practice systems thinking Further research