A virus may help lead to a cure for two energy ills: solar power storage and cheaper, cleaner hydrogen fuel production.
MIT researchers engineered a harmless bacterial virus to mimic the way photosynthesis splits water into oxygen and hydrogen. Extracting hydrogen from water using sunlight would allow energy from the sun to be stored as hydrogen, for use later via a fuel cell—not just when the sun is shining. The viral-spawned hydrogen fuel might also be used to power automobiles.
In plants, pigments absorb sunlight, and catalysts trigger the reactions that split H2O molecules. In the MIT lab, the virus, called M13, attracts and binds to a pigment, zinc porphyrins, and a catalyst, iridium oxide. The pigments catch the sunlight and transport the energy down the virus as if it were a wire.
The M13 virus serves as a type of scaffolding, spacing the pigment and catalysts in such a way that allows the water-splitting reaction to occur.
To prevent the viruses from clumping together or losing their working shape, Professor Angela Belcher (right) and her team encapsulated them in a microgel matrix.
As of now, the resulting hydrogen atoms separate into their component protons and electrons, but the researchers are developing a new step that would re-assemble them into hydrogen atoms and molecules.
There is a daunting combination of problems to be solved before this or any other artificial photosynthetic system could actually be useful for energy conversion. This is unlikely to happen in the near future. Nevertheless, the design idea illustrated in this paper could ultimately help with an important piece of the puzzle.
Mallouk explains that for the virus system to compete with existing solar power strategies, it would need to perform better than plant photosynthesis—at least 10 times more efficiently. Such a system would also have to carry out the reactions a billion times and do so more cheaply than currently in the lab.
The MIT team is already looking to replace the expensive and somewhat rare iridium as a catalyst. In two years, Belcher hopes to have a prototype for the viral system that is durable and self-sustaining.
Image 1: Flickr/der_makabere
Image 2: Dominick Reuter