Photosynthesis is one of the most important chemical reactions on our planet, responsible directly and indirectly for the oxygen we breathe and the food we eat. It is powered by sunlight, with about 1 percent of the energy of the Sun ending up in the plant. Now, researchers have dramatically increased the efficiency and done away with sunlight altogether.

As reported in Nature Food, the team used a two-step process. First, they used an electrocatalytic process to create acetate – the main component of vinegar – from carbon dioxide, water, and electricity. Acetate can then be consumed by food-producing organisms to grow in complete darkness.

“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," Elizabeth Hann, a doctoral candidate at UC Riverside and co-lead author of the study, said in a statement. 

"This technology is a more efficient method of turning solar energy into food, as compared to food production that relies on biological photosynthesis.”

When employing solar panels to produce electricity, the team found that the conversion efficiency of sunlight into food was 18 times higher for yeast. Making algae grow was about four times more energy efficient. The team also tested this on fungal mycelium that produces mushrooms.

“With our approach 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, a UC Riverside assistant professor of chemical and environmental engineering.

The team also tested the approach on known crops to see if they could be grown with acetate and without sunlight. Black-eyed peas, tomatoes, tobacco, rice, canola, and green peas were all able to utilize carbon from acetate when cultivated in the dark.

“We found that a wide range of crops could take the acetate we provided and build it into the major molecular building blocks an organism needs to grow and thrive. With some breeding and engineering that we are currently working on we might 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.

The approach could be employed to increase carbon capture approaches using cultivars, as well as growing food without sunlight both on Earth – and maybe even in space.