Scientists have discovered a way to create food that does not require biological photosynthesis by using artificial photosynthesis. A two-step electrocatalytic process converts carbon dioxide, electricity, and water into acetate. In order to grow, food-producing organisms consume acetate in the dark. The hybrid organic-inorganic system has the potential to increase the efficiency of sunlight conversion into food by up to 18 times for some foods.
For millions of years, plants have used photosynthesis to convert water, carbon dioxide, and sunlight energy into plant biomass and the foods we eat. However, this process is extremely inefficient, with only about 1% of the energy found in sunlight reaching the plant. Scientists at UC Riverside and the University of Delaware have discovered a way to create food without the need for biological photosynthesis entirely by using artificial photosynthesis.
The study, which was published in the journal Nature Food, employs a two-step electrocatalytic process to convert carbon dioxide, electricity, and water into acetate, the main component of vinegar. In order to grow, food-producing organisms consume acetate in the dark. This hybrid organic-inorganic system, when combined with solar panels to generate the electricity to power the electrocatalysis, could increase the conversion efficiency of sunlight into food by up to 18 times for some foods.
“We sought to identify a new way of producing food that could break through the limits normally imposed by biological photosynthesis,” said corresponding author Robert Jinkerson, an assistant professor of chemical and environmental engineering at UC Riverside.
We were able to grow food-producing organisms without the assistance of biological photosynthesis. Typically, these organisms are grown on sugars derived from plants or inputs derived from petroleum – which is a byproduct of biological photosynthesis that occurred millions of years ago.
Elizabeth Hann
The output of the electrolyzer was optimized to support the growth of food-producing organisms in order to integrate all of the system’s components. Electrolyzers are electrical devices that 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 most acetate ever produced in an electrolyzer to date.
“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,” said corresponding author Feng Jiao of the University of Delaware.
Experiments showed 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. Producing algae with this technology is approximately fourfold more energy-efficient than growing it photosynthetically. Yeast production is about 18-fold more energy efficient than how it is typically cultivated using sugar extracted from corn.
“We were able to grow food-producing organisms without the assistance of biological photosynthesis. Typically, these organisms are grown on sugars derived from plants or inputs derived from petroleum – which is a byproduct of biological photosynthesis that occurred millions of years ago. This technology is a more efficient method of converting solar energy into food than biological photosynthesis “said Elizabeth Hann, a doctoral candidate in the Jinkerson Lab and co-lead author of the study.
The feasibility of using this technology to cultivate crop plants was also investigated. When grown in the dark, cowpea, tomato, tobacco, rice, canola, and green pea were all able to use carbon from acetate.
“We discovered that a wide variety of crops could convert the acetate we provided into the major molecular building blocks required by organisms to grow and thrive. We may 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” said Marcus Harland-Dunaway, a doctoral candidate in the Jinkerson Lab and the study’s co-lead author.
By liberating agriculture from complete dependence on the sun, artificial photosynthesis opens the door to countless possibilities for growing food under the increasingly difficult conditions imposed by anthropogenic climate change. Drought, 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 could also be grown in cities and other areas currently unsuitable for agriculture, and even provide food for future space explorers.
“Using artificial photosynthesis approaches to produce food could be a paradigm shift for how we feed people. By increasing the efficiency of food production, less land is needed, lessening the impact agriculture has on the environment. And for agriculture in non-traditional environments, like outer space, the increased energy efficiency could help feed more crew members with less inputs,” said Jinkerson.
This food production method was submitted to NASA’s Deep Space Food Challenge and was a Phase I winner. The Deep Space Food Challenge is an international competition in which teams compete for prizes for developing novel and game-changing food technologies that require few inputs while producing safe, nutritious, and palatable food for long-duration space missions.
“Imagine giant vessels growing tomato plants in the dark and on Mars — how much easier would that be for future Martians?” said co-author and director of the UC Riverside Plant Transformation Research Center Martha Orozco-Cárdenas.
