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Artificial photosynthesis makes food production more energy efficient


Researchers have found a way to completely circumvent the need for biological photosynthesis and create food independent of sunlight by using artificial photosynthesis. The study was published in the journal, Nature Food.

Researchers have used a two-step electrocatalytic process to convert carbon dioxide, electricity and water into acetate, the main component of vinegar. Food-producing organisms then consume acetate in the dark to grow.

Combined with solar panels to generate the electricity to power the electrocatalysis, this hybrid organic-inorganic system can increase the conversion efficiency of sunlight into food, up to 18 times more efficient for some foods.

“With our approach, we have been trying to identify a new way of producing food that can break through the limits normally imposed by biological photosynthesis,” said the corresponding author Robert Jinkerson, a UC Riverside assistant professor of chemistry and environmental engineering, said.

In order to integrate all the components of the system together, the output of the electrolyser has been optimized to support the growth of food producing organisms. Electrolysers are devices that use electricity to convert raw materials such as carbon dioxide into useful molecules and products. The amount of acetate produced was increased while the amount of salt used was reduced, leading to the highest levels of acetate ever produced in an electrolyzer.

“By using a modern two-step tandem CO2 electrolysis setup developed in our laboratory, we were able to achieve a high selectivity for acetate that cannot be obtained by conventional CO2 electrolysis routes,” the corresponding author Feng Jiao at the University of Delaware.

Experiments have shown that a wide range of food-producing organisms can be grown in the dark directly on the acetate-rich electrolyzer output, including green algae, yeast, and fungal mycelium that produce mushrooms. The production of algae with this technology is about four times more energy efficient than growing it photosynthesically. Yeast production is about 18 times more energy efficient than how it is typically grown with sugar extracted from maize.

“We were able to grow food-producing organisms without any contributions from biological photosynthesis. Typically, these organisms are grown on sugars from plants or inputs derived from petroleum – which is a product of biological photosynthesis that took place millions of years ago. Technology is more efficient method of converting solar energy into food, compared to food production that relies on biological photosynthesis, “said Elizabeth Hann, a doctoral candidate in the Jinkerson Lab and co-lead author of the study.

The potential of using this technology to grow crop plants has also been investigated. Cowpea, tomato, tobacco, rice, canola and green pea could all use carbon from acetate when grown in the dark.

“We have found that a wide range of crops can take the acetate we have provided and build it into the most important molecular building blocks that an organism needs to grow and thrive. With a degree of breeding and engineering to which we are currently working, we may be able to grow crops with acetate as an extra energy source to boost crop yields, “said Marcus Harland-Dunaway, a doctoral candidate in the Jinkerson Lab and co-lead author of the study.

By freeing agriculture from total dependence on the sun, artificial photosynthesis opens the door to countless possibilities for the cultivation of food under the increasingly difficult conditions imposed 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 grew in less resource-intensive, controlled environments. Crops can also be grown in cities and other areas that are not currently suitable for agriculture, and even provide food for future space explorers.

“The use of artificial photosynthesis approaches to produce food can be a paradigm shift in how we feed people. By increasing the efficiency of food production, less land is needed, which reduces the impact that agriculture has on the environment. And for “Agriculture in non-traditional environments, such as outer space, can help increase energy efficiency by feeding more crew members with less input,” Jinkerson said.

This approach to food production was presented at NASA’s Deep Space Food Challenge where it was a Phase I winner. The Deep Space Food Challenge is an international competition where prizes are awarded to teams to create new and game-changing food technologies that require minimal input and maximize safe, nutritious and tasty food outputs for long-term space missions.

“Imagine giant vessels one day growing tomato plants in the dark and on Mars – how much easier will it be for future Martians?” said co-author Martha Orozco-Cardenas, director of the UC Riverside Plant Transformation Research Center.


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