HHMI Teachers’ Workshop: Biofuels – More Than Ethanol From Corn Starch

1. HHMI Teachers’ Workshop:Biofuels – More Than Ethanol From Corn Starch Aditya Kunjapur, Ph.D. Candidate, MIT July 20, 2014

2. Outline • Context for biofuels and key facts • Photosynthesis and carbon fixation • Feedstocks • Fuels • Recap

3. Outline • Context for biofuels and key facts • Photosynthesis and carbon fixation • Feedstocks • Fuels • Recap

4. What is “BioEnergy” According to the International Energy Agency (IEA): “Material which is directly or indirectly produced by photosynthesis and which is utilized as a feedstock in the manufacture of fuels and substitutes for petrochemical and other energy intensive products.” IEA Bioenergy: http://www.ieabioenergy.com/IEABioenergy.aspx

5. Overview of BioEnergy Photosynthesis • Enzymatic • Same organism • Different organism • Plants • Algae • Cyanobacteria Photons Fuels or Chemicals Biomass Energy + CO2 Inorganic Molecules • Ethanol • Biodiesel • Jet Fuel • Methane Chemosynthesis • Thermochemical • Pyrolysis • Gasification • Chemolithotrophs (in deep oceans, isolated caves, etc) Energy Capture Chemical Conversion

6. Some advantages of bioenergy compared to other renewables • The only renewable source that can replace fossil fuels in all energy markets – in the production of heat, electricity, and fuels for transport (IEA) • The source of a variety of drop-in liquid fuels • The source of petroleum in the first place • The primary way by which atmospheric CO2 is consumed

8. Breakdown of US renewables in 2011 http://www.eia.gov/totalenergy/data/monthly/pdf/sec10_3.pdf

9. Percentage of the world’s energy • Biomass-based energy accounted for ~10% of world total primary energy supply in 2009 • Includes cooking/heating in developing countries • Global production of biofuels: • 2000: 16 billion liters • 2011: 100+ billion liters • Total road transport fuel globally: 3% • Brazil: 23% Source: IEA

10. Life cycle of traditional biofuels Important consideration: life cycle greenhouse gas emissions SC Opinion on Greenhouse Gas Accounting in Relation to Bioenergy: http://www.eea.europa.eu/about-us/governance/scientific-committee/sc-opinions/opinions-on-scientific-issues/ Image: http://www.extension.org/sites/default/files/w/2/22/BiofuelLifeCycle.jpg

12. Outline • Context for biofuels and key facts • Photosynthesis and carbon fixation • Feedstocks • Fuels • Recap

13. Photosynthesis: Overview • Oxidation/reduction (Redox) reactions • CO2 gets reduced to glucose • H2O gets oxidized to O2 Image: http://www.phschool.com/science/biology_place/biocoach/images/photosynth/photo1.gif

14. Photosynthesis: Inside a Chloroplast Image: http://hyperphysics.phy-astr.gsu.edu/hbase/organic/imgorg/rubc3.gif

15. Photosystems convert light energy into reducing equivalents Image: http://www.biologycorner.com/resources/photosystem.jpg

16. The Calvin Cycle uses those reducing equivalents to turn CO2 into sugar Image: https://benchprep.com/blog/wp-content/uploads/2012/08/Calvin_cycle.jpg

18. Typical efficiency of photosynthesis 47% Non-Bioavailable Photons 100% Sunlight 53% (in 400-700 nm range) 30% Not Absorbed 40% Loss in Dark and Photo-Respiration 68% Loss in Conversion of ATP and NADPH to glucose 37% (Absorbed Photon Energy) ~5% Net Leaf Efficiency 9% (Collected as sugar) 28% (Energy Captured in Chlorophyll) 24% Wavelength Mismatch Figure based on statistics listed here: http://en.wikipedia.org/wiki/Photosynthetic_efficiency

19. Outline • Context for biofuels and key facts • Photosynthesis and carbon fixation • Feedstocks • Fuels • Recap

20. Feedstocks Two categories of photosynthetic organisms: • Those that capture light energy into non-fuel biomass - Chemical conversion still required • Those that capture light energy and produce a fuel - Only physical separation required Image: http://www1.eere.energy.gov/biomass/images/Feedstock1.jpg

21. Estimated corn use for ethanol production (2011): 4.9 billion bushels or 279 billion pounds Image: http://ericpetersautos.com/wp-content/uploads/2012/12/corn-1.gif Source of facts: EIA – Biofuel Trends and Issues – Oct 2012

22. Drawbacks of Corn as a Feedstock • Used for food • Grows slowly • Grows only on arable land • Provides low energy per acre • Is an annual crop Image: http://media.treehugger.com/assets/images/2011/10/bushcorn-jj-001.jpg http://www.shirkebiofuels.com/images/biofuel-feedstock.gif

24. Can grow up to 8 feet in 6 weeks Image: http://newswire.uark.edu/images/miscanthus.JPG

25. Energy yield per acre does not favor corn ? Source: “Biodiesel from microalgae.” http://www.sciencedirect.com/science/article/pii/S0734975007000262#

26. Bioreactors/ponds used to grow algae Bioreactors required to cultivate high cell densities Images: http://www.inventgeek.com/Projects/Photo-Bio-reactor-V2/main.jpg http://assets.inhabitat.com/files/bioreactor1.jpg ;

27. Bioreactors/ponds used to grow algae • Algal cells make up very small fraction of pond • Dewatering and processing is cost-prohibitive Images: both from http://www.asulightworks.com/blog/asu-and-ua-team-arid-raceway-algae-test-bed

29. Cellulose

31. I Gelfandet al. Nature000, 1-4 (2013) doi:10.1038/nature11811

32. Cellulosic biofuel – a reality?

33. Outline • Context for biofuels and key facts • Photosynthesis and carbon fixation • Feedstocks • Fuels • Recap

34. Pathway to ethanol Under anaerobic conditions (no O2): Glycolysis (~10 enzymatic reactions) Pyruvatedecarboxylase Alcohol dehydrogenase Image: http://www.emc.maricopa.edu/faculty/farabee/biobk/alcferm.gif

35. Drawbacks of ethanol • Hygroscopic • Miscible with water • Low energy density • Requires different distribution system than gasoline • Limit to how much can be added to conventional engines

37. The E10 “Blend Wall”

38. Alternative fuel options • Longer, branched alcohols • Biodiesel • Methane • Methanogens • CO2 + 4H2 CH4 + 2H2O • Important for waste-to-energy Image: http://canola.ab.ca/image.axd/images/uploads/news/bio_pump_200x250.jpg?m=Crop&w=200

39. Images: (Left) http://www2.raritanval.edu/departments/Science/full-time/Weber/Microbiology%20Majors/Chpater5/chapter5sub/figure_05_30_labeled.jpg

40. Outline • Context for biofuels and key facts • Photosynthesis and carbon fixation • Feedstocks • Fuels • Recap

41. Overview of BioEnergy Photosynthesis • Enzymatic • Same organism • Different organism • Plants • Algae • Cyanobacteria Photons Fuels or Chemicals Biomass Energy + CO2 Inorganic Molecules • Ethanol • Biodiesel • Jet Fuel • Methane Chemosynthesis • Thermochemical • Pyrolysis • Gasification • Chemolithotrophs (in deep oceans, isolated caves, etc) Energy Capture Chemical Conversion

42. Recap and take home points • Traditional biofuels have several drawbacks • When evaluating a biofuel process, consider: • Carbon lifecycle • Food versus fuel • Land (or water) required • Feedstock transportation • Desired end fuel • Research efforts directed toward production of advanced and cellulosic biofuels make most sense(just my opinion!)

43. Thank you for listening! Questions?