Bioengineering for Pollution Prevention through Development of Biobased Energy and Materials

1. Bioengineering for Pollution Prevention through Development of Biobased Energy and Materials Dianne Ahmann and John Dorgan Colorado School of Mines December 14, 2005

2. Introduction Bioengineering Pollution Prevention Key Targets for Research • Materials • plant- or microbe-generated constituents • biodegradable • potentially CO2-neutral • Energy • biologically-generated or altered • renewable • potentially CO2-neutral

3. The Issue of Petroleum Petroleum dependence • primary feedstock for plastics • primary fuel for transportation Petroleum supplies

4. Petroleum-based Pollution • petroplastics • greenhouse gases petroleum + O2CO2 + H2O + CO + SOx + NOx + CH4 + VOCs

5. Biotechnological Platforms • Genetic Engineering • Bioreactors • Bioseparations and Bioprocessing

6. Genetic Engineering biomaterials and biofuels are produced by biosynthetic pathways external signal internal signal Y E1 E2 E3 X A B C D cell growth • gene expression control • metabolic and pathway engineering

8. Bioreactors Optimization of growth conditions is essential for high-volume, low-cost commodities • pH • temperature • ionic strength • redox potential • cell density • substrate concentration • product concentration • unit process integration • membrane-recycle bioreactor • two-phase partitioning bioreactor • process models • metabolic flux analysis • transport phenomena • on-line sensing • electrode-based • spectroscopic

9. Bioseparations and Bioprocessing Separations frequently dominate economics of bioprocessing because products must be recovered from dilute aqueous solutions • filtrations • micro, ultra, nano, electro • fouling • pervaporation • extractions • two-phase partitioning • bioreactors • non-solvent based • processing • supercritical CO2

10. Bioplastics and Biomaterials Polylactides Polyhydroxyalkanoates Starches Soy Oils and Proteins Cellulosics

11. Polylactides: Chemistry

12. Polylactides: Embodied Energy

13. Polylactides: Properties and Applications • Applications • food service items and • packaging • surgical implants • diapers • clothing, carpet, upholstery • Controllable factors • molecular weight • architecture (branched or linear) • crystallinity • stereochemistry (polyD, polyL, polyDL) • Properties • Tm = 145-230°C • translucence: clear to opaque • tensile strength ~ PET, PP, PS • absorbent, wrinkle- and wear- resistent • low inflammability • biodegradability Natureworks PLA • Limitations and Research Priorities • low melt strength • low T of heat distortion • high permeability to H2O and CO2 • rheology (flow behavior) • micro and nanocomposites

14. Polyhydroxyalkanoates (PHAs): Chemistry

15. PHAs: Biochemistry and Genetics

16. PHAs: Properties and Applications • Controllable factors • substrate feeding • substrate ratios • e.g. pentanoic acid + butyric acid  poly(3HB-co-3HV) • substrates with functional groups • e.g. halogenated, branched, or aromatic moieties • inhibitors • e.g. acrylate to inhibit fatty acid degradation • gene dosage • heterologous expression • active pathways • enzyme properties • Properties • tough, durable, moldable • highly biodegradable by enzymes • low O2, H2O permeability • (20X  PLA; 2-4X  PET and PP) • relatively brittle • Applications • packaging • disposables • coatings and adhesives • textiles • Research Priorities • cost • property variety and controllability

17. Starches amylose amylopectin

18. Starch-based Plastics • Limitations and Priorities • water susceptibility • gas and water permeability • use in composites

19. Soy-based Plastics • John Deere initiative • protein + oil • composite or blend use?

20. Cellulose-based Plastics • cellulose acetate • macrocomposites • micro- and nano- composites

21. Biofuels Bioethanol Biodiesel Biohydrogen Biodesulfurized Fossil Fuels

22. Bioethanol: Process CO2 + H2O O2 • cellulases CO2 + sunlight • acid • mech disruption • steam explosion • distillation • pervaporation • simultaneous saccharification • and fermentation (SSF) • genetically engineered organisms • pentose fermentation

23. Bioethanol: Cellulase • multi-enzyme complex • endoglucanase • exoglucanase • beta-glucosidase (cellobiase) • extracellular • not well-understood • insoluble substrate • relatively slow • commercially available • primary market in textiles • expensive

24. Bioethanol: Feedstocks • food crops • Brazil: sugar cane • US: corn • conventional agriculture • biomass and wastes • crop residues • wood chips • forest thinnings • low-input crops • Research Priorities • low-input biomass feedstocks • cellulase engineering • consolidated bioprocessing • cellulase synthesis • cellulose hydrolysis • pentose + hexose fermentation

25. Biodiesel www.biodiesel.org • biodiesel • produced from plant oils • US: soybeans • Canada, Europe: canola • most widely available biofuel • intended for vegetable oil! • petroleum diesel advantages • ignitability • low clogging • superior lubrication

26. Biodiesel: Process triglyceride CO2 + sunlight transesterification + CH3OH biodiesel

27. Biodiesel: Lipases • catalysis required • acid  slower; allows greater water content in oil • alkali  faster; difficult to recover glycerol from alkali waste • enzymatic (lipase)  rapid, specific, water-tolerant, aqueous waste • Research Priority: lipase (carboxylesterase) development • single most widely used enzyme class in biotechnology! • highly selective • extracellular and secreted in great quantity • crystal structures are known  engineering possible • detergents, food ingredients, pharmaceuticals

28. Biohydrogen • “clean” burning: • 2H2 + O2 2H2O • sources: • steam reforming of CH4 • electrolysis of water • direct photolysis • indirect photolysis • fermentations

29. BioH2: Direct Photolysis light + H2O + CO2 H2 + biomass • Research Priorities • O2 sensitivity • intermittence • bioreactor shading

30. BioH2: Indirect Photolysis ATP + N2 + H+ NH3 + H2 • energy intensive • O2 tolerant • NH3 sensitive • relatively slow • Research Priorities • uptake hydrogenases • nitrogenase engr • antenna reduction • cultivation optimization • cyanobacterial diversity

31. BioH2: Fermentation and the Water-Gas Shift CH2O  light biomass + ferm products + H2 • continuous • anaerobic • energy intensive • low yield • sugars • organic wastes • Research Priorities • uptake hydrogenases • waste substrates • cultivation optimization • metabolic engineering • gas separation technologies

32. BioH2: Comparative Rates

33. Biodesulfurization

35. NSF/EPA Technology for a Sustainable Environment Program Contributions 1995-2004 • metabolic engineering (7) • microbe engineering to withstand bioreactor conditions (3) • bioreactors, bioprocessing, bioseparations, sensing (10) • bioplastics, biomaterials, polymerization catalysts (20) • bioenergy and biofuels (11)

36. Acknowledgements April Richards Robert Wellek Reviewers: Anastasios Melis, Richard Wool, David Levin, Lonnie Ingram, Mark Segal Maria Ghirardi, Michael Seibert, Pin-Ching Maness (NREL) colleagues and students of the Colorado School of Mines John Berger and Laura Hollingsworth