DEPARTMENT OF
ENERGY, ENVIRONMENTAL &
Seminar
Cupples
II, Room 100
Monday,
December 4, 2006
2:30
pm to 4:00 pm
Biological
Hydrogen Production: Catalysts and Processes
Maria
L. Ghirardi
National
Renewable Energy Laboratory, Golden, CO
In
nature, three major types of biological processes are responsible for hydrogen
production: dark anaerobic fermentation, nitrogenase-catalyzed
processes, and hydrogenase-catalyzed production in
oxygenic organisms. Dark fermentative H2-production
requires sugars as electron donors and has a maximum biological molar yield of
4 H2/glucose. Nitrogenase-catalyzed reactions are found mostly in anoxygenic photosynthetic bacteria, and, although light
conversion efficiencies of about 6% of sunlight can potentially be achieved,
the reaction depends on organic substrates as electron donors, in most cases.
Finally, photosynthetic organisms that use water as the electron donor and hydrogenases as the H2-producing catalysts have
the potentially highest conversion efficiencies of about 10% of sunlight.
However, hydrogenases are extremely sensitive to O2,
a by-product of oxygenic photosynthesis, and H2-production in these
organisms can only be sustained under anaerobic conditions. I will describe approaches being investigated
to address the issue of the O2-sensitivity of the hydrogenase, either through molecular engineering or
through physiological manipulations of the cultures. I will also address the possibility of
integrating different H2-production processes in a single system
that takes advantages of the activities of fermentative and photosynthetic
organisms.
Return to CURRENT
SEMINAR PAGE
Return to Department of Energy, Environmental
and Chemical Engineering