Artificial photosynthesis can produce food without sunshine

For millions of years, plants have developed photosynthesis to convert carbon dioxide, water, and solar energy into plant biomass and food for humans to consume. Only around 1% of the energy in sunlight is actually used by the plant due to this extremely inefficient mechanism. By employing artificial photosynthesis, researchers at UC Riverside and the University of Delaware have discovered a technique to produce food without the need for biological photosynthesis at all.

The study, which was published in Nature Food, used a two-step electrocatalytic process to change carbon dioxide, water, and energy into acetate, which is vinegar's primary ingredient. Then, in the dark, food-producing organisms develop by consuming acetate. When coupled with photovoltaic cells to supply the energy for the electrocatalysis, this hybrid organic-inorganic system has the potential to enhance sunlight-to-food conversion efficiency by up to eighteen times for certain food types.

"We aimed to discover a novel method of food production that could surpass the constraints typically imposed by biological photosynthesis," stated corresponding author Robert Jinkerson, an assistant professor of chemical and environmental engineering at UC Riverside.

The electrolyzer's output was tuned to promote the development of organisms that produce food in order to integrate all the system's components. Electrolyzers are machines that use electricity to create usable chemicals and products from raw materials like carbon dioxide. The greatest amounts of acetate ever generated in an electrolyzer were achieved by increasing the amount of acetate produced while decreasing the amount of salt needed.

According to corresponding author Feng Jiao of the University of Delaware, "we were able to achieve a high selectivity towards acetate that cannot be accessed through conventional CO2 electrolysis routes using a state-of-the-art two-step tandem CO2 electrolysis setup developed in our laboratory."

Experiments revealed that a variety of food-producing organisms, such as green algae, yeast, and fungal mycelium that produces mushrooms, may be grown in the dark directly on the acetate-rich electrolyzer output. Using this approach, algae may be produced at an energy efficiency around four times higher than when grown photosynthetically. Compared to traditional methods of cultivation that use maize sugar, yeast culture is approximately eighteen times more energy-efficient.

Food-producing creatures might be grown by us without the aid of biological photosynthesis. These creatures are usually grown on plant-derived sugars or petroleum-derived inputs, which are byproducts of biological photosynthesis that occurred millions of years ago. Compared to food production that depends on biological photosynthesis, this technique is a more effective way to convert solar energy into food, according to Elizabeth Hann, a doctorate candidate at the Jinkerson Lab and co-lead author of the paper.

It was also looked at if this technique might be used to produce agricultural plants. When grown in the dark, cowpea, tomato, tobacco, rice, canola, and green pea might all use the carbon from acetate.

We discovered that a variety of crops could use the acetate we supplied to create the essential molecular building blocks required by living things in order to develop and flourish. Co-lead author of the study and doctorate candidate at the Jinkerson Lab Marcus Harland-Dunaway stated, "We might be able to grow crops with acetate as an extra energy source to boost crop yields with some breeding and engineering that we are currently working on."

Artificial photosynthesis frees agriculture from total solar dependency, creating a plethora of opportunities for food production in the face of increasingly challenging environmental conditions brought on by human-caused climate change. Global food security would be less threatened by droughts, floods, and a shortage of land if crops for people and animals were grown in regulated, less resource-intensive habitats. Not only might crops be produced in places that aren't now appropriate for agriculture, such cities, but they could also be cultivated to feed space travelers in the future.

The production of food by artificial photosynthesis has the potential to revolutionize the way humans eat. Agriculture's environmental effect is reduced when more land is needed for food production, which increases efficiency. Jinkerson said, "And the increased energy efficiency could help feed more crew members with less inputs for agriculture in non-traditional environments, like space."

This food production method was entered into NASA's Deep Space Food Challenge and was selected as a Phase I winner. Teams who develop innovative and revolutionary food technologies that optimize safe, nutrient-dense, and tasty food outputs for extended space missions while requiring the least amount of inputs are eligible to win awards in the Deep Space Food Challenge, an international competition.

Imagine massive spacecraft cultivating tomatoes in the dark on Mars at some point. Can you imagine how much simpler it would be for future Martians? stated Martha Orozco-Cárdenas, a co-author and the director of the Plant Transformation Research Center at UC Riverside.

Sean Overa, Dang Le, and Andres Narvaez also made contributions to the study. A hybrid inorganic–biological artificial photosynthesis system for energy-efficient food production is described in this open-access publication.

The study was funded by the U.S. Department of Energy, the Foundation for Food and Agricultural Research (FFAR), the Link Foundation, the U.S. National Science Foundation, the U.S. National Science Foundation, and the Translational Research Institute for Space Health (TRISH) through NASA (NNX16AO69A). The Foundation for Food and Agriculture Research does not necessarily endorse the opinions expressed in this publication; the writers alone are responsible for its content.