Hydrogen Production.ppt

Hydrogen Production.ppt

• 1.
  Microbial Production of Hydrogen Dr.Bhavesh Patel Principal V.P. and R.P.T.P. Science College, Vallabh Vidyanagar Email- [email protected]
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  Outline • Importance ofhydrogen production • Types of hydrogen production – Fermentative – Photosynthetic • The hydrogenase enzyme • Hydrogen production by Chlamydomonas reinhardtii • Research proposal
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  Importance of Hydrogenas an Alternative Fuel • Increased levels of CO2 from fossil fuels cause an increase in the Greenhouse Effect • One of the detrimental effects of the Greenhouse Effect is Global Warming • Combustion of Hydrogen produces water, which is not detrimental to the environment
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  Effects of GlobalWarming • Changes in climate • Sea level rise due to melting of polar icecaps – US seas rising 2.5-3.0mm/yr – By year 2050 it is most likely sea levels will rise by 15cm, but 1% chance they will rise one meter (Titus et al 1991) – One meter rise in sea level will cause $270-475 billion dollars in damage (Titus and Narayanam 1995)
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  Microbial Hydrogen Production •Types of microbial hydrogen production – Fermentative – Photosynthetic (aerobic/anaerobic) • Most interest in hydrogen production research in US during the Energy Crisis of the 1970s • Interest in hydrogen production again in 1990s due to the awareness of Global Warming, etc.
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  Fermentative Production of Hydrogen •Clostridia species - Clostridia beijerincki – Used in fuel cell that produced 15mA over 20 days using waste from alcohol distillery (Taguchi et al 1992) • Methanogens -Methanotrix soehngenii • Archeabacteria -Pyrococcus furiosus (hyperthermophile) • Eschericia coli - Formate Hydrogen Lyase pathway, which is inefficient
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  Photosynthetic Production of Hydrogen •Purple Sulfur bacteria (Thiocapsa and Chromantium) • Non-Sulfur bacteria (Rhodospirillum and Rhodopseudomonas) • Green Algae (Chlamydomonas reinhardtii) • Advantages: – Photosynthetic organsims produce more hydrogen than fermentative organisms (Nandi and Sengupta 1998) – Photosynthetic organisms only require light and water
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  Photosynthetic Hydrogen Production Mechanisms •The purple sulfur bacteria and the non- sulfur bacteria produce hydrogen through a reversible hydrogenase and as a by-product of denitrification. • Chlamydomonas reinhardtii a green algae, produces hydrogen through hydrogenase. • Hydrogenase is induced under anaerobic conditions
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  Hydrogenase • Many bacteriause it for H2 dissimulation to use the electrons for electron transport • Two types of hydrogenases – Nickel-Iron centered - dissimulate hydrogen – Iron-only centered - evolve H2
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  Mechanism of Hydrogenase •Hydrogen Dissimulation – H2 Hydrogenase 2H+ + 2e- • Hydrogen Evolution – Fd-reduced + 2H+ Hydrogenase H2
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  Comparison of Hydrogenase Yields Chlamydomonashas the highest hydrogen yield
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  Advantages of Using C.reinhardtii • Cheap and easy to grow – Requires fluorescent light and 5% CO2 – Grows at room temp. in water • Mutants have been isolated that are more energetically efficient (lack Photosystem I) • Research into its life cycle and flagella have yielded useful molecular techniques for studying the organism
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  Chlamydomonas reinhardtii • Green-alga(eukaryotic) • Biflagellated, unicellular, photosynthetic • Reproduces asexually or sexually under adverse conditions
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  Chlamydomonas reinhardtii
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  C. reinhardtii Hydrogenase •Enzyme located in the chloroplast • Receives electrons from reduced ferrodoxin • Hydrogenase stimulated under anaerobic conditions (Happe et el 1994) • Hydrogenase inhibited by O2, which is produced by C. reinhardtii during photosynthesis
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  Research Needs • Investigatehydrogenase oxygen inhibition • Investigate production of hydrogen by the Photosystem I mutant
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  Research Proposal • Problem:Hydrogenase in C. reinhardtii inhibited by oxygen, which is made by the organism. • Solution: Determine Oxygen binding site on hydrogenase and create a clone with lower O2 binding and therefore higher H2 production.
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  Research Approach • Isolategene for hydrogenase (BAC library has recently become available) • Sequence the hydrogenase gene and determine the oxygen binding site. – Create hydrogenase clone that does not bind oxygen through site-directed mutagenesis. • Isolate hydrogenase deficient C. reinhardtii mutant through UV-mutagenesis. • Introduce mutant hydrogenase into hydrogenase deficient clone.