Photosynthesis can be considered one of nature's superpowers, but it's surprisingly inefficient, with only about 1 percent of the energy found in sunlight making it inside the plant.
Now, scientists at UC Riverside and the University of Delaware say they have found a method to bypass the need for biological photosynthesis, allowing them to create food without sunlight via artificial photosynthesis, a press statement reveals.
The researchers, who published their findings in Nature Food, used a two-step electrocatalytic process to convert carbon dioxide, electricity, and water into acetate, which is the main component in vinegar.
They then applied the acetate to food-producing organisms in the dark, causing these organisms to grow. Their method could provide a much-needed food growth alternative in the face of a catastrophic climate crisis.
Artificial photosynthesis: Cultivating food without sunlight
Though the UC Riverside researchers highlight the fact their method requires no sunlight, they do point out that it can work incredibly effectively alongside renewable solar energy. Interestingly, they say they can combine their method with solar panels to generate the electricity required to power the electrolysis. This would increase the conversion efficiency of sunlight into food by up to 18 times compared to some foods.
That means the method can use sunlight, though it is not reliant on the Sun's energy, and it can also function using other forms of electricity generation.
"With our approach, we sought to identify a new way of producing food that could break through the limits normally imposed by biological photosynthesis," corresponding author Robert Jinkerson, a UC Riverside assistant professor of chemical and environmental engineering, said in the statement.
During their research, the scientists discovered that a large variety of food could be produced in the dark using their method, including green algae, yeast, and fungal mycelium, which produces mushrooms. According to their findings, growing yeast using their method is 18 times more energy-efficient than the way it is typically cultivated by extracting sugar from corn.
"We were able to grow food-producing organisms without any contributions from biological photosynthesis. Typically, these organisms are cultivated on sugars derived from plants or inputs derived from petroleum—which is a product of biological photosynthesis that took place millions of years ago. This technology is a more efficient method of turning solar energy into food, as 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.
Climate change and space exploration require important food growth alternatives
The researchers also optimized their electrolyzer to produce the highest levels of acetate ever produced in an electrolyzer to date. What's more, they found that crop plants, including cowpea, tomato, rice, green pea, and tobacco, all have the potential to be grown in the dark using the carbon from acetate. There's even a possibility that acetate could improve crop yields, though more research is required.
The researchers believe that by reducing the reliance on direct sunlight, artificial photosynthesis could provide an important alternative for food growth in the coming years, as the world adapts to the worst effects of climate change — including droughts, floods, and reduced land availability. "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," Jinkerson explained.
In fact, the UC Riverside team were Phase I winners in NASA's Deep Space Food Challenge. As co-author Martha Orozco-Cárdenas put it, "imagine someday giant vessels growing tomato plants in the dark and on Mars—how much easier would that be for future Martians?"