Photosynthesis has evolved in plants over millions of years, converting water, carbon dioxide, and sunlight energy into plant biomass and the foods we eat. This process, however, is very inefficient: only about 1% of the energy contained in sunlight reaches the plant. Scientists at the University of California, Riverside and the University of Delaware have found a way to bypass the need for biological photosynthesis altogether and create food independent of sunlight through artificial photosynthesis.

The study, published in Nature Food, uses a two-step electrocatalytic process to convert carbon dioxide, electricity and water into acetate, a form of vinegar’s main ingredient. Food-producing organisms then consume the acetate in the dark to grow. Combined with solar panels to generate electricity to power electrocatalysis, this organic-inorganic hybrid system can increase the efficiency of converting sunlight into food, up to 18 times more efficiently for some foods.

“Through our approach, we sought to define a new way of producing food that could overcome the limitations typically imposed by biological photosynthesis,” said correspondent author Robert Ginkerson, assistant professor of chemical and environmental engineering at the University of California, Riverside.

In order to bring all the components of the system together, the power of the electrolyzer has been optimized to support the growth of food organisms. Electrolyzers are devices that use electricity to convert raw materials such as carbon dioxide into useful molecules and products. The amount of acetate produced has been increased and the amount of salt used has been reduced, resulting in the highest levels of acetate ever produced in an electrolytic cell to date.

“Using a state-of-the-art two-stage tandem CO2 electrolysis plant developed in our laboratory, we were able to achieve high selectivity for acetate, which cannot be obtained with conventional CO2 electrolysis methods,” said corresponding author Feng Jiao from the University. Delaware.

Experiments have shown that a wide range of food organisms can be grown in the dark directly from the acetate-rich outlet of an electrolyser, including green algae, yeasts, and fungal mycelium that fungi produce. Producing algae with this technology is about four times more energy efficient than growing them by photosynthesis. Yeast production is about 18 times more energy efficient than conventional yeast production using sugar extracted from corn.

“We have been able to grow food-producing organisms without the involvement of biological photosynthesis. Typically, these organisms are cultivated on plant-derived sugar or on raw materials derived from petroleum, which is the product of biological photosynthesis that took place millions of years ago. This technology is a more efficient method of converting solar energy into food compared to food production based on biological photosynthesis,” said Elizabeth Hann, doctoral student in Jinkerson’s lab and co-author of the study.

The potential of using this technology for growing crops has also been explored. Vigna, tomatoes, tobacco, rice, rapeseed and green peas are able to utilize carbon from acetate when grown in the dark.

“We have found that a wide variety of crops can take our provided acetate and turn it into the basic molecular building blocks the body needs to grow and thrive. With some of the breeding and engineering techniques we are currently working on, we could grow crops with acetate as an additional source of energy to increase yields,” said Markus Harland-Dunaway, a doctoral student in the Jinkerson lab and co-author of the study. the study.

By freeing agriculture from total dependence on the sun, artificial photosynthesis opens the door to countless possibilities for growing food in the increasingly difficult conditions brought about by anthropogenic climate change. Droughts, floods and reduced land availability would be less of a threat to global food security if crops for humans and animals were grown in a less resource-intensive controlled environment. The crop can also be grown in cities and other areas currently unsuitable for agriculture, and even provide food for future space explorers.

“Using artificial photosynthesis techniques to produce food could change the paradigm of how we feed people. By increasing the efficiency of food production, less land is needed, which reduces the environmental impact of agriculture. And for agriculture in non-traditional environments like space, increased energy efficiency could help feed more crew members at a lower cost,” Jinkerson said.

This approach to food production was introduced by NASA in the Deep Space Food Challenge, where it was the Phase I winner. maximum yield of safe, nutritious and tasty foods for long space missions.

“Imagine someday giant ships growing tomatoes in the dark and on Mars – how much easier would that be for future Martians?” said co-author Martha Orosco-Cardenas, director of the Plant Transformation Research Center at the University of California, Riverside.

Link: Hann EC, Overa S, Harland-Dunaway M, et al. Hybrid inorganic-biological artificial photosynthesis system for energy-efficient food production. Nat Food. 2022;3(6):461-471. doi:10.1038/s43016-022-00530-x

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