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Scientists at US Department of Energy's Argonne National
Laboratory are working to chemically manipulate algae for
production of the next generation of renewable fuels - hydrogen
gas.
"We believe there is a fundamental advantage in looking
at the production of hydrogen by photosynthesis as a renewable
fuel" - senior chemist David Tiede said. "Right
now, ethanol is being produced from corn, but generating ethanol
from corn is a thermodynamically much more inefficient process."
Some varieties of algae - a kind of unicellular plant - contain
an enzyme called hydrogenase that can create small
amounts of hydrogen gas. Tiede said many believe this is used
by nature as a way to get rid of excess reducing equivalents
that are produced under high light conditions, but there is
little benefit to the plant.
Tiede and his group are trying to find a way to take the
part of the enzyme that creates the gas and introduce it into
the photosynthesis process. The result would be a large amount
of hydrogen gas - possibly on par with the amount of oxygen
created.
"Biology can do it, but it's making it do it at 5-10
percent yield - that's the problem"- Tiede said. "What
we would like to do is take that catalyst out of hydrogenase
and put it into the photosynthetic protein framework. We are
fortunate to have Professor Thomas Rauchfuss as a collaborator
from the University of Illinois at Champaign-Urbana, who is
an expert on the synthesis of hydrogenase active site mimics."
Algae has several benefits over corn in fuel production.
It can be grown in a closed system almost anywhere - including
deserts or even rooftops - and there is no competition for
food or fertile soil. Algae is also easier to harvest because
it has no roots or fruit and grows dispersed in water.
"If you have terrestrial plants like corn, you are restricted
to where you could grow them" - Tiede said. "There
is a problem now with biofuel crops competing with food crops
because they are both using the same space. Algae provides
an alternative, which can be grown in a closed photobioreactor
analogous to a microbial fermentor that you could move any
place."
Tiede admitted the research is in its beginning phases, but
he is confident in his team and their research goals. The
next step is to create a way to attach the catalytic enzyme
to the molecule.
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