'Reverse photosynthesis' could change fuel production

Researchers in Denmark have discovered that a certain enzyme causes sunlight to break down the chemical bonds in plants. The finding could improve industrial processes such as the production of biofuels.

Deutsche Welle, 17 April 2016

Photosynthesis is a process in which plants convert sunlight into chemical energy that can be later released as fuel. But now, a group of scientists from the University of Copenhagen have found that adding an enzyme called monooxygenase to the process causes sunlight to break down plant material instead of helping create it. They refer to this phenomenon as "reverse photosynthesis."

The discovery could be applied to processes that require the breakdown of chemical bonds, such as the production of bioethanol, which is made from biomass via a fermentation process.

In a press release, Professor Claus Felby from the Plant Science Centre at the University of Copenhagen, the head of the study, called the discovery a "game changer" that could transform the production of fuels and chemicals, increasing efficiency and decreasing pollution.

Great usage potential

The first step to producing bioethanol is breaking down cellulose, an organic material that forms the walls in plant cells. This is exactly what happens when monooxygenase is added to the photosynthesis process.

Ethanol is widely used as engine fuel

"Basically, we have found a new way of using solar energy - going directly from sunlight to chemistry," Felby told DW. "This opens up a lot of possibilities."

The scientists' lab tests indicated that applying this process resulted in much faster production of ethanol and at lower temperatures. The duration of some of the chemical reactions was reduced from hours to minutes when sunlight was involved.

Ethanol has a multitude of uses in the modern world, mostly as engine fuel, but also as an ingredient in medical and personal care products.

The team also found that the same process can be applied to oxidizing methane. This produces methanol, a key ingredient in the manufacture of different chemicals.

"Methanol currently requires very large and expensive steel units to produce," explained Felby. "If our method was applied to this process, you would only need small, simple production units, something similar to a greenhouse."

Need to test large-scale application

While the process has proven effective in a lab environment, the scientists need to do further research to determine how it would work in real life.

"We are now working on exploring this," David Cannella, a co-author of the study, told DW. "You need to make sure that sunlight penetrates the organic material that you are converting, and we still need to work out how to do this."

Cannella feels optimistic about the commercial applicability of the process, as does Felby.

"We have to determine the exact amount of light needed for the process and how and when to apply it," said Felby. "But that's just a question of engineering."

He added that going directly from sunlight to chemical energy results in very little energy loss: "It's a near-perfect process."

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