You probably don’t think about it often, but when we fill up the car we’re doing nothing but exploiting the most powerful biological system for the production of energy: photosynthesis. Oil, coal and natural gas, on the other hand, are nothing but products of the incessant activity with which plants convert sunlight and CO2 in organic substances; condensed and distilled, in this case, from millions of years spent underground. It is possible to exploit the same process to obtain artificial fuels, renewable and perhaps less harmful to the environment? To date, unfortunately, the answer is negative, but science is at work, and is starting to give the first results. To prove it, a study by the University of Chicago presented on the pages of Nature Catalysis, which describes a new method for artificial photosynthesis, at least 10 times more efficient than those previously developed.
Even so – warn the authors of the study – we are far from something that can really provide an answer to the growing energy needs of our species. But at the very least, it’s a step in the right direction, given that going without fossil fuels in the future will require equally energy-efficient alternatives. “Many people don’t realize the real challenge: not even nature has a solution for the amount of energy we are using“, explains Wenbin Lin, a chemist at the University of Chicago who participated in the research. “In the future, we’re going to have to do better than nature, and that’s scary.”
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Fears aside, one of the possibilities being studied at the moment is that of hack photosynthesis. That is, finding a way to exploit the technique with which plants produce energy using sunlight and carbon dioxide, and exploit it to produce the zero-impact (or almost) fuels that are most convenient for us, such as ethanol or methane . Easier said than done, of course: natural photosynthesis produces glucose, i.e. a carbohydrate, a molecule made up of a chain of oxygen, carbon and hydrogen atoms linked together, while to obtain methane, chemists must be able to transform the reaction to produce a very different molecule, composed of a single carbon atom surrounded by four hydrogen atoms (CH4).
To date, the task has proved extremely complex. However, the Chicago researchers have experimented with a new method, which for now has proved extremely promising: add amino acids to artificial photosynthesis, something that had never been attempted until today. Their technique involves using a material called M or For metal-organic framework, which is submerged in a solution containing cobalt, and different types of amino acids.
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By optimizing the choice of amino acids, they have shown that in this way it is possible to improve all phases of the artificial photosynthesis reaction, reaching an efficiency 10 times higher than that of the attempts carried out to date. Still too little, we said, to imagine its use on an industrial scale: “The way things currently stand – explains Lin – we would have to increase the effectiveness by several orders of magnitude to hope to obtain sufficient quantities of methane for our energy needs” . Therefore, if it is not yet a question of a solution to humanity’s energy problems, it is in any case an excellent step forward, which could give a decisive boost to this field of study.
