Artificial Photosynthesis May Solve Carbon Emission Problem

A potentially game-changing breakthrough in artificial photosynthesis may be able to solve the world's carbon emission problem, according to new research.

Atmospheric carbon dioxide (CO2), a greenhouse gas, is now at its highest level in at least three million years, with 2013 seeing a record high in greenhouse gas emissions. And the more CO2 released into the atmosphere, the warmer our world becomes.

But now, scientists with the US Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley may have finally found the solution.

They have created a unique system - made simply out of nanowires and bacteria - that can capture CO2 emissions before they are vented into the atmosphere. It mimics the natural process of photosynthesis, during which plants use the energy in sunlight to synthesize carbohydrates from CO2 and water.

However, their idea converts CO2 and water into acetate, the most common building block today for biosynthesis.

Even more amazing is that they then use solar energy to convert the CO2 into valuable chemical products, including biodegradable plastics, pharmaceutical drugs and even liquid fuels.

"We believe our system is a revolutionary leap forward in the field of artificial photosynthesis," Peidong Yang, one of the study's lead authors, said in a statement. "Our system has the potential to fundamentally change the chemical and oil industry in that we can produce chemicals and fuels in a totally renewable way, rather than extracting them from deep below the ground."

While countries like the United States are trying to curb carbon emissions from coal power plants, the burning of fossil fuels will likely remain a significant source of energy for humanity in the foreseeable future. So figuring out a way to capture this carbon and lessen our effect on climate change is crucial. Scientists have come up with some technologies already for capturing carbon - for example, turning to carbon-trapping "sponges," converting it to a harmless organic compound, or even using baking soda to prevent it from leaking into the atmosphere.

However, these innovations are a long way off from widespread commercial use, and other technologies come with their own environmental challenges.

But this new artificial photosynthetic technique solves the storage problem by putting the captured CO2 to good use.

"In natural photosynthesis, leaves harvest solar energy and carbon dioxide is reduced and combined with water for the synthesis of molecular products that form biomass," explained Chris Chang, an expert in catalysts for carbon-neutral energy conversions. "In our system, nanowires harvest solar energy and deliver electrons to bacteria, where carbon dioxide is reduced and combined with water for the synthesis of a variety of targeted, value-added chemical products."

By combining biocompatible light-capturing nanowire arrays with certain bacterial populations, the researchers have created a win/win situation. That is, they help solve the carbon problem while also use green energy to manufacture new commercial products.

"Our system represents an emerging alliance between the fields of materials sciences and biology, where opportunities to make new functional devices can mix and match components of each discipline," said Michelle Chang, an expert in biosynthesis.

A key to this technology is using the bacteria S. ovate, which is a great CO2 catalyst that can make acetate - a versatile chemical that can be used to make all sorts of other chemicals like butanol, a fuel comparable to gasoline.

Not to mention with this approach, the Berkeley team achieved a solar energy conversion efficiency of up to 0.38-percent for about 200 hours under simulated sunlight, which is about the same as that of a leaf.

"We are currently working on our second generation system which has a solar-to-chemical conversion efficiency of three-percent," Yang added. "Once we can reach a conversion efficiency of 10-percent in a cost effective manner, the technology should be commercially viable."

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