Artificial photosynthesis can produce food without sunshine

Plants grow in complete darkness in an acetate medium that replaces biological photosynthesis. Credit: Marcus Harland-Dunaway/UCR

Photosynthesis has evolved in plants over millions of years to convert water, carbon dioxide and the energy of sunlight into plant biomass and the food we eat. However, this process is very inefficient: only about 1% of the energy from sunlight ends up in the plant. Scientists from UC Riverside and the University of Delaware have found a way to bypass the need for biological photosynthesis altogether and create food that is independent of sunlight by using artificial photosynthesis.

The research, published in Nature Food, uses 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 for electrocatalysis, this hybrid organic-inorganic system could increase the conversion efficiency of sunlight into food, up to 18 times more efficient for some foods.

“With our approach, we sought to find a new way to produce food that could break the limits normally imposed by biological photosynthesis,” said corresponding author Robert Jinkerson, an assistant professor of chemical and environmental engineering at UC Riverside.

To integrate all components of the system together, the output of the electrolyzer was optimized to support the growth of food-producing 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 was increased, while the amount of salt used was decreased, resulting in the highest levels of acetate ever produced in an electrolyzer.

“Using a state-of-the-art two-step tandem CO2 electrolysis setup developed in our lab, we were able to achieve a high selectivity to acetate that is not accessible via conventional CO2 electrolysis pathways,” said corresponding author Feng Jiao of the University of Delaware.

Experiments showed that a wide variety of food-producing organisms can be grown in the dark directly on the acetate-rich electrolysis output, including green algae, yeast and fungal mycelium that produce mushrooms. Producing algae with this technology is about four times more energy efficient than growing it photosynthetically. Yeast production is about 18 times more energy efficient than how it is commonly grown with sugar extracted from corn.

Kunstmatige fotosynthese kan voedsel produceren zonder zonneschijn

A combined electrochemical-biological system for the production of food from CO2aCO2 electrolysis uses electricity (generated by photovoltaics) to produce CO. to put2 and H2O in O2 and acetate. This process is optimized to produce an effluent that is ideal to support the growth of food-producing organisms. bChlamydomonasSaccharomycesmushroom-producing fungus and a variety of dish crops were grown using the effluent produced by the electrolyser. cThe organisms grown using the effluent produced by the electrolyser serve as food or food products. This system is capable of using CO. make food independent of photosynthesis2huh2Oh and solar energy. Credit: Nature Food (2022). DOI: 10.1038/s43016-022-00530-x

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

The potential for using this technology to grow crops was also explored. Cowpea, tomato, tobacco, rice, canola, and green pea were all able to utilize carbon from acetate when grown in the dark.

“We found that a wide variety of crops could take the acetate we provide and build it into the key molecular building blocks an organism needs to grow and thrive. With some breeding and engineering we’re currently working on, we can perhaps grow crops with acetate as an additional energy source to increase crop yields,” said Marcus Harland-Dunaway, a PhD student in the Jinkerson Lab and co-lead author of the study.

By liberating agriculture from complete dependence on the sun, artificial photosynthesis opens the door to countless opportunities to grow food under the increasingly difficult conditions imposed by anthropogenic climate change. Drought, flooding and reduced land availability would pose less of a threat to global food security if crops for humans and animals were grown in less resource-intensive, controlled environments. Crops could also be grown in cities and other areas currently unsuitable for agriculture, even providing food for future space explorers.

“Using artificial photosynthesis approaches to produce food could be a paradigm shift for how we feed people. Increasing the efficiency of food production means less land is needed, reducing the impact of agriculture on the environment. And for agriculture in non-traditional environments, like space, the increased energy efficiency could help power more crew members with less input,” said Jinkerson.

This approach to food production was submitted to 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 groundbreaking food technologies that require minimal inputs and maximize safe, nutritious and tasty food outputs for long-term space missions.

“Imagine if one day giant ships grow tomato plants in the dark and on Mars — how much easier would that be for future Martians?” said co-author Martha Orozco-Cárdenas, director of the UC Riverside Plant Transformation Research Center.

The future of biofuels in the dark

More information:
Elizabeth C. Hann et al, A hybrid inorganic-biological artificial photosynthesis system for energy-efficient food production, Nature Food (2022). DOI: 10.1038/s43016-022-00530-x

Provided by University of California – Riverside

Quote: Artificial photosynthesis can produce food without sunshine (2022, June 23) retrieved June 24, 2022 from

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