Feb
7
A New Solar Bio Photo Conversion System Makes Hydrogen
February 7, 2011 | 3 Comments
Oak Ridge National Laboratory researchers have developed a biohybrid photo conversion system – based on the interaction of photosynthetic plant proteins with synthetic polymers – that can convert visible light into hydrogen fuel. This is another part of the first step to making solar panels for directly producing fuel.
The research team’s work seeks to mimic photosynthesis, the natural process carried out by plants, algae and some bacterial species that converts sunlight energy into chemical energy and sustains much of the life on earth.
If successful to scale at a low cost enough for individual, family or business installations much of the fuel supply issue would simply fade away into history as fuel using power equipment to do work follow the fuel supply. Perhaps ORNL has found the dream to reality of developing new materials to harness the sun’s energy for electricity and fuel production.
The ORNL researchers have demonstrated and confirmed with small-angle neutron scattering analysis that light harvesting complex II (LHC-II) proteins can self-assemble with polymers into a synthetic membrane structure and produce hydrogen.
The ability of LHC-II to force the assembly of structural polymers into an ordered, layered state – instead of languishing in an ineffectual mush – may well make possible the development of biohybrid photo conversion systems. These systems would consist of high surface area, light-collecting panes that use the proteins combined with a catalyst such as platinum to convert the sunlight into hydrogen, which could be used for fuel.
The researchers project that energy-producing photo conversion systems similar to photovoltaic cells to generate hydrogen fuel will compare to the way plants and other photosynthetic organisms convert light to energy.
ORNL researcher Hugh O’Neill, of the lab’s Center for Structural Molecular Biology, said, “Making a, self-repairing synthetic photo conversion system is a pretty tall order. The ability to control structure and order in these materials for self-repair is of interest because, as the system degrades, it loses its effectiveness. This is the first example of a protein altering the phase behavior of a synthetic polymer that we have found in the literature. This finding could be exploited for the introduction of self-repair mechanisms in future solar conversion systems.” If the team is proven right, the lifespan of a unit would be greatly expanded improving the economics.
Biohybrid Photo Conversion System. Click image for more info.
On the production front, small angle neutron scattering analysis performed at ORNL’s High Flux Isotope Reactor (HFIR) showed that the LHC-II, when introduced into a liquid environment that contained polymers, interacted with polymers to form lamellar sheets similar to those found in natural photosynthetic membranes.
The research is another step building on previous ORNL investigations into the energy-conversion capabilities of platinized photosystem I complexes – and how synthetic systems based on plant biochemistry can become part of the solution to the global energy challenge.
O’Neill explains the significance of the research at this stage saying, “We’re building on the photosynthesis research to explore the development of self-assembly in biohybrid systems. The neutron studies give us direct evidence that this is occurring.”
The researchers confirmed the proteins’ structural behavior through analysis with ORNL’s High Flux Isotope Reactor Bio-SANS, a small-angle neutron scattering instrument specifically designed for analysis of biomolecular materials. The Bio-SANS uses “cold source” neutrons, in which energy is removed by passing them through cryogenically chilled hydrogen, are ideal for studying the molecular structures of biological tissue and polymers.
Now here is the surprise, the LHC-II protein for the experiment was derived from a simple source: spinach procured from a local grocer’s produce section. The spinach is processed to separate the LHC-II proteins from other cellular components. Eventually, the protein could be synthetically produced and optimized to respond to light.
O’Neill said the primary role of the LHC-II protein is as a solar collector, absorbing sunlight and transferring it to the photosynthetic reaction centers, maximizing their output. “However, this study shows that LHC-II can also carry out electron transfer reactions, a role not known to occur in vivo,” he said.
O’Neill credits a wide array of skill sets at ORNL for getting the work this far saying, “That’s one of the nice things about working at a national laboratory. Expertise is available from a variety of organizations.”
The research team comes from various laboratory organizations including its Chemical Sciences Division, Neutron Scattering Sciences Division, the Center for Structural Molecular Biology and the Center for Nanophase Materials Sciences. The team members are O’Neill, William T. Heller, and Kunlun Hong, all of ORNL; Dimitry Smolensky of the University of Tennessee; and Mateus Cardoso, a former postdoctoral researcher at ORNL now of the Laboratio Nacional de Luz Sincrotron in Brazil.
The work has been published in the journal Energy & Environmental Science. Funding support came from the Laboratory-Directed Research and Development budget. The DOE Office of Science supports the HFIR.
The very idea that one’s roof could produce fuel ready for storage and use, generate electricity from photovoltaic and gather heat with thermal panels could make possible for nearly everyone outside of urban areas, fully energy independent.
These are goals worth the effort and research investment. There is a long way to go, but getting there should prove worth it.
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They say it can repair the membrane, but what happens when the polymer breaks down, then what? Still needs to be replaced right?
Thank you for your thoughtful post!
My comment wasn’t intended to be critical of the science. I didn’t compose it well. I was wondering how long the system would last in its present state.