The Alternative World of Biofuels
Hailey DeVries IB Major
Ethanol: A Biofuel
• Form of alcohol currently used to produce alternative fuel for cars. • USA: second leading producer worldwide (after Brazil – sugar cane). • In past years, dramatic increase in the amount of ethanol produced.
How is it made from corn?
1. Grow and collect grain.
2. Grind kernels into meal. 3. Heat and enzymes convert starch to sugar.
4. Anaerobic respiration by yeast.
5. Alcohol (ethanol) is distilled out of mixture.
Ethanol
How is it made from Cellulosics?
1. Collection, storage & transportation to refinery.
2. Dirt & debris removed from material and then shredded into small particles. 3. Heat, pressure or acid treatment. Enzymes in solution are used to breakdown cellulose, hemicellulose to sugars. Lignin is removed.
4. Syrup of sugars is filtered from solids. 5. Anaerobic fermentation by bacteria to produce alcohol (and carbon dioxide). 6. Further enzymatic breakdown of cellulose and lignin. 7. Anaerobic fermentation by bacteria to produce alcohol (and carbon dioxide). **This method 8. Alcohol is distilled. used for plants 9. More water removed. such as Miscanthus** 10. Stored for distribution and use.
Biofuels are a BIG deal ($500,000,000 over 10 yr)
• BP funded Energy Biosciences Institute (EBI) at UI + UC Berkeley to help find alternative forms of fuel. • Research by EBI explores the possibilities of using monoculture feedstocks instead of corn seed to produce ethanol.
A little background
• Before the plow, the Midwest was a grassland with large stores of soil organic matter. • Land conversion to row crop agriculture (corn-soybean rotation): – depleted soil stores of C + N – caused soil erosion – polluted above/belowground water through nitrates derived from fertilizer.
Objectives of EBI Project
• quantify the major pools and fluxes in C, N, water cycles in fields with four different types of feedstock crops; • determine how and when interactions of soil microbial and insect populations affect these cycles; • By studying the entire cycle, understand how feedstock crops affect major ‘ecosystem services’: – sequester atmospheric carbon – retain soil nitrogen – minimize water contamination – reduce greenhouse gases.
Biofuel Feedstocks
Corn
Switchgrass (Panicum virgatum)
Miscanthus (M. giganteus)
restored prairie
Why use these feedstocks?
• High rates of biomass accumulation with minimal nutrient inputs • Perennials
– Extended growing season – Low demand for nutrients, fertilizer, pesticides
• Could stop harmful environmental impacts of corn-soybean rotations
Benefits
• Compared to fossil fuels, biofuels from corn reduce greenhouse gas emissions:
– – corn: by ~40% switchgrass by ~115% (theoretical analysis).
Benefits
• Net biomass yields of perennials is much greater than corn:
– Miscanthus ~1400 g C/m2 – switchgrass ~550 g C/m2
**Note: 1 ton = 46 bu
Benefits
• Net energy yields are greater for perennials than annuals.
Drawbacks?
• Feedstock crops likely to affect natural biodiversity of ecosystem. • Takes 3 years to reach economic maturity. • Planting of perennial rhizomes long and laborious. • Must perform studies with comparisons of feedstocks to determine costs and benefits (This study is the first).
Study Site: UI South Farm
Corn, switchgrass, and Miscanthus (2nd year of growth) (Above)
Switchgrass and Miscanthus (Left)
Experimental Design (Phase One)
• Conducted at the UIUC Energy Farm. • Each crop replicated four times; crops randomly placed in site; three 0.7-ha plots and one 3.8-ha plot. • Meterological tower measures surfaceatmosphere exchange of CO2, water vapor, energy, N2O,and methane. • Tile drains under each plot collects drainage water to measure leaching. • Nutrients in vegetation (using stable isotopes) measured. • Herbivore damage and changes in soil microbial communities measured.
Analysis
• Accumulation of soil C measured as changes in C isotope composition. • Measure herbivores and microbial communities to determine how mineralization, nitrification, denitrification are regulated. • Expect ecosystem process differences to occur within first three years of establishment. • Data used to put into a model (DAYCENT) to extrapolate results regionally).
• Examine how feedstock crops interact with climate to influence cycles of C, N, and water. • Conduct along longitudinal gradient from Ohio to California. • Gradient dominated by changes in precipitation.
Phase Two
Predictions (based on succession)
• During establishment phase: – C and N stocks will increase rapidly due to reduced losses to atmosphere and groundwater. – soil C will accumulate.
Predictions
• Rapid changes in N cycle due to rapid conversion of leaky N system (annuals) to conserved N system (perennials) – Feedstocks require less fertilizer. – Rapid uptake of N due to root systems present throughout the year resulting in less leaching. – Nitrate loss due to drainage to decrease from 30 to <2 kg N/ha/yr. – Less loss of N via denitrification due to limited availability of nitrate because of plant uptake.
Predictions
• Annuals vs. perennials will cause differences in the water cycle through altered rates of evapotranspiration--> – differences in soil moisture and run-off; – differences will drive changes in nutrient cycling and microbial activity.
• Insect diversity will increase during establishment in prairie. • Impact of above-ground herbivory on C and N cycles will be greatest in monoculture feedstocks.
Why does it matter?
• Provides methodology for other biofuel systems, e.g. – sugar beets + poplar plantations in temperate regions – sugar cane in the tropics • Allows for understanding the impact of feedstocks on the ecosystem. • Greater yields of ethanol from perennial biomass may decrease the land use for biofuels and allow more land use for food production.
Want to learn more???
• Check out http://miscanthus.uiuc.edu/
Acknowledgments
Thank you to: Dr. Augspurger & Mr. Mike Masters
DeLucia et. al. 2007. EBI 2007: Environmental impact and sustainability of feedstock production. Program Summary pg.1-16
Yates, Diana. 2008. Miscanthus can meet US biofuels goal using less land. Inside Illinois 28: 10-13.
http://www1.eere.energy.gov/biomass/images/greenhouse_gas_by_fuel.jpg http://www.cocorahs.org/media/images/us_precip.png
http://miscanthus.uiuc.edu/?page_id=11