In recent centuries, innovative farming equipment and synthetic chemical fertilizers have boosted food production to feed an increasingly growing population of people. As any backyard gardener knows, growing plant-based food-lettuce, tomatoes, herbs, grains, pumpkins-still mostly relies on the age-old strategy: Plant seeds in nutritious soil, keep them well hydrated with plenty of sunlight, and wait for them to grow.
The reason? While sunny regions naturally provide enough light to grow crops, areas with colder winters often need grow lights and greenhouses part of the year. Dubbed “Electro-agriculture,” the approach uses solar panels to trigger a chemical reaction that turns ambient CO2 into an energy source called acetate.
Certain mushrooms, yeast, and algae already consume acetate as food. With a slight genetic tweak, we could also engineer other common foods such as grains, tomatoes, or lettuce to consume acetate. With more research, it might even be possible to bypass traditional photosynthesis with acetate and grow plants in the dark.
“Right now, we are at about four percent efficiency, which is already four times higher than for photosynthesis, and because everything is more efficient with this method, the CO2 footprint associated with the production of the food becomes much smaller.” Man Versus Food Agriculture is one of the most difficult domains in which to reduce carbon emissions.
In plants and some bacteria, green-tinted molecular machines called chloroplasts absorb sunlight and churn that light into energy. True to form, vertical farms grow crops on stacked shelves rather than large horizontal fields.
The method often relies on hydroponics, in which plants absorb nutrients from a water-based system instead of soil, similar to AeroGarden but at an industrial scale. These systems run indoors, so plants can grow all year.
Much of the “Electricity supplied to the LED grow lights in conventional vertical farming is lost to heat,” explained the team. The system captures ambient CO2 from the air and uses water and electricity to convert the gas into different molecules-including ethanol and acetate, which is “Plant food” for some species.
Acetate is a vinegar-like chemical at the heart of many biological reactions. One recent study found that acetate made from CO2 could be used to cultivate yeast, mushrooms, and a type of green algae in total darkness without the need for natural photosynthesis.
These initial results got scientists wondering: Can we use acetate alone to replace photosynthesis? Not quite. Most adult crop plants naturally require photosynthesis to build up their weight and size.
Plants grown with electro-ag would need to shift their metabolism to consume acetate-which most adult plants struggle to process-as a primary food source. Plants can use the molecule for energy as they’re germinating from seeds.
By tweaking genes involved in acetate metabolism, it might be possible to reawaken the plants’ natural ability to digest the molecule. Amping up a gene involved in acetate metabolism boosted their ability to eat it.
The middle section would use this energy to break down CO2 and generate acetate to feed plants growing in the bottom section. Depending on the type of crop, this section could hold roughly three to seven “Floors” of plants stacked on top of each other, like trays in a fridge.
Currently, scientists are tweaking tomato and lettuce genes to increase their abilities to use acetate as food. Plants aside, a similar technology-in theory-could also be used for cultivating dairy and plant-based meat, although the idea hasn’t been tested yet.