This document summarizes research into using hydrogenase enzymes and glycerol to produce hydrogen as an alternative energy source. It discusses different biological and photolytic methods for hydrogen production and their limitations. The document focuses on using hydrogenase enzymes directly as electrocatalysts for fuel cells, looking at improving their stability and activity when integrated into electrode materials. Overall the research aims to develop hydrogenase-based technologies as alternatives to platinum in fuel cells and electrolysis.
1. Reviewed by Holden Ranz
ChE 391: Independent Study
Advised by Professor Piergiovanni
2. Original Interest
Alternative energy Algae
What can be done to make
algae fuel more sustainable?
Biodiesel processing
generates residual glycerol
Certain unicellular organisms
can produce H2
○ Glycerol be used as substrate
for H2 production?
3. Fermentative Hydrogen
Dark Fermentation
glycerol
1,3-propanediol
+ hydrogen
Biological limitations
Require carbohydrates
Low yields of energy
Specific T, P, pH requirements
Enterobacter
Clostridium
5. Biophotolysis
Light-driven decomposition
of water
Direct Biophotolysis
green algae, cyanobacteria
Advantages:
○ High solar energy conversion
Disadvantages:
○ O2 inhibition
7. Biohydrogen Downfalls
Low yields
Inhibition of hydrogen production
Requires low levels of H2, O2
Gas separation needed
Biological sensitivity
Metabolic pathways for alcohol
formation
8. Evolved Interest
Hydrogenase enzymes
Catalyzes redox: 2H+ H2
Can hydrogenases be used as electrocatalysts for fuel
cell applications?
Surprising
amount of
development in
FC technology
and enzymes!
9. Hydrogenase Enzymes
Serve function that is closely related to needs
for technological systems
Can be used in multiple alternative energy
applications
10. Active Site
Nature uses nickel, iron, and sulfur for H2
production/activation
Fe-Fe (Clostridium)
Ni-Fe
Hydrophobic channels
11. Enzyme Electrodes
Anodes
Cathodes
Stability/structure
Adsorption to carbon
support
○ PGE, GCE, carbon felt
Encapsulation in polymeric
porous gels
○ Si-O-Si network
12. Progress of Enzyme Electrodes
CO poisoning not an issue
Energy conversion of enzyme electrode
comparable to noble metal based
commercial fuel electrode
Alternative for fuel cells and electrolysis
13. Continuing Research
Improving electrode
stability and activity
Doping of sol-gel
○ Methyl viologen
○ Carbon nanotubes
Integration of
photosystem
Porphyrin - TiO2
colloidal system
14. References
Adhikari, Sushil, Sandun Fernando, and Agus Haryanto. "Hydrogen Production from
Glycerin by Steam Reforming over Nickel Catalysts." Renewable Energy 33 (2008):
1097-100. Web.
Demirbas, Ayhan. "Progress and Recent Trends in Biofuels." Progress in Energy and
Combustion Science 33 (2007): 1-18. Web.
Ito, Takeshi, Yutaka Nakashimada, Koichiro Senba, Tomoaki Matsui, and Naomichi
Nishio.
"Hydrogen and Ethanol Production from Glycerol-Containing Wastes Discharged after
Biodiesel Manufacturing Process." Journal of Bioscience and Bioengineering 100.3
(2005): 260-65. Web.
Liu, Fei, and Baishan Fang. "Optimization of Bio-hydrogen Production from Biodiesel
Wastes by Klebsiella Pneumoniae." Biotechnology Journal 2 (2007): 374-80. Web.
Yang, Zhiman, Rongbo Guo, Xiaohui Xu, Xiaolei Fan, and Shengjun Luo.
"Fermentative Hydrogen Production from Lipid-extracted Microalgal Biomass
Residues." Applied Energy 88.10 (2011): 3468-472. Print.
Yu, J., and P. Takahashi. "Biophotolysis-based Hydrogen Production by Cyanobacteria
and Green Microalgae." Http://www.formatex.org/microbio/pdf/Pages79-89.pdf. 2007.
Web. 19 Feb. 2012.
"Improvement of Fermentative Hydrogen Production: Various Approaches." Web.
http://www.fao.org/docrep/w7241e/w7241e06.htm
http://www.bw2e.com/images/dia2.gif
http://www.hielscher.com/image/biodiesel_process_chart_p0500.gif
http://www.theprofessionalgroup.com/Enterobacter.html
http://world.edu/wp-content/uploads/2011/12/cyanobacteria1.jpg
http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-
uk.org.uk/mag/wimsmall/green.html
My original interest in this project was motivated by my research interests in sustainable methods of generating alternative energy.
One of the most talked about sources of alternative energy to date is microalgae for their high oil content and is supported by President Obama for supplying our future energy needs.
Unfortunately, biodiesel derived from algae is much more expensive than current methods of extracting fossil fuels due to high capital and operating costs.
So that prompts the question…
Processing is outlined by this schematic, and as you can see one of the major byproducts is glycerin or glycerol (removal of organic chains from triglycerides).
Glycerol is relatively inexpensive and readily available so it is treated as a waste product.
Converting glycerol into a value-added chemical could could aid in overcoming hurdles to sustainable algae fuel, so that is where I began my research.
Turns out that a number of unicellular organisms can produce hydrogen, but can glycerol be used as a substrate?
The first few papers that I discovered discussed methods of fermenting glycerol-containing wastes discharged from biodiesel processing.
Bacteria that have been shown to convert glycerol to 1,3-propanediol via dark fermentation (absence of light) include the genus enterobacter and clostridium, however typical substrates used by most fermentative bacteria are carbohydrates like glucose and other sugars. Yield of H2 using glycerol is less than yield using glucose.
Also biological processes are carried out largely at ambient T and P, and most bacteria cannot sustain at pH<5.0, sensitive to environmental changes
They are less energy intensive than most chemical process
Such research has shown positive results, but in terms of using wastes from biodiesel manufacturing they emphasize that there is still significant work to be done in terms of discovery of more effective hydrogen-producing microorgansims and genetic engineering.
This lead me to research fermentative hydrogen production more generally to better understand what is causing these limitations.
I discovered there are multiple mechanisms other than dark fermentation by which microorganisms produce hydrogen.
Additionally, there are organisms which perform photofermentation
Comparison of biological and technological systems for…
Solar energy conversion to fuels
Utilization of stored chemical energy
Biology and technology use functional steps that are quite analogous, key difference is that biology uses a proton-motive force while electrical circuits use a electromotive force in technological systems
Serve function that is closely related to needs for technological systems
Can be used in multiple alternative energy applications