From advancements in LEDs to using light energy captured by solar panels, a noble pursuit in the world of agriculture is finding ways to reduce our demand for our planet’s resources. As a lighting company that can’t deny the benefits of relying on sunlight vs. artificial grow lamps, we’re always ecstatic to hear about advancements in lighting/energy efficiency.
We’ve talked in the past about how some crops can be genetically modified to increase their biological photosynthetic productivity and how micro-naps can cut down on energy demands by up to 30%. These things are surely helpful, but when there are estimates that plants are only converting about 1% of the sunlight they consume into creating new biomass, you can’t help but feel these approaches are simply Band-Aids for a broken bone that needs a cast.
So, what happens if we could take light and photosynthesis out of the equation yet still grow food crops just as successfully and maybe even more so? Not only would that be fantastic news for our planet, but it also opens the door to successfully growing plants off-world, from the International Space Station (ISS) to Mars.
Growing plants without light shining on them (biological photosynthesis) may seem like a novel idea that’s downright science fiction.
However, artificial photosynthesis isn’t a new concept; there is usually just a greater focus on improving biological photosynthetic production. And while that’s completely logical, because of the horrible efficiency of biological photosynthesis, we might be playing a losing game trying to improve it alone.
That’s why researchers from both the University of Delaware and the University of California wanted to see if they could grow plants without the traditional photosynthetic process. And after studying nine different food crops along with algae, yeast, and mushroom-producing fungi, they say it’s a real possibility.
While many gardeners refer to giving plant nutrients as feeding them, our crops make their own food (sugars) using photosynthesis. To do that, they need to convert light, water, and carbon dioxide into usable energy to grow. But what if we could actually feed our crops and skip a long and inefficient process, allowing them to get to the biomass building stage faster?
By deriving acetate from carbon dioxide, electricity, and water — using a two-step electrocatalytic process — Elizabeth Hann and her colleagues are getting closer to doing just that. And to say their results have been impressive is putting it lightly.
What Happens When Crops Are Grown In The Dark?
After studying crops such as lettuce, rice, cowpea, green pea, canola, tomato, pepper, tobacco, and Arabidopsis (A. thaliana), U.D. researchers say all plants were able to able to take in carbon from the acetate. Amongst the food crops, lettuce produced the best results. Yeast won overall, being able to be grown 18 times more efficiently under this form of artificial photosynthesis vs. the usual process, which involves corn sugars.
The study defines energy efficiency as the increase in biomass energy content divided by the required solar energy input needed to create the acetone.
Essentially, artificial photosynthesis works because it lets plants skip an incredibly demanding and inefficient task, quickly giving them an endless and readily available amount of fuel they need to grow.
But it doesn’t end there! When this process used solar energy to power the electrolyzer, just one-fourth of the energy normally needed when using sunlight and natural photosynthesis was able to grow the same amount of food. This is incredible since, in comparison, food crops are unable to use 99% of the light they capture.
Even with their success, Elizabeth Hann and her team aren’t finished. They say their next step is producing a more effective acetate mixture by improving their electrolyzer system along with exploring ways to bioengineer plants to grow on acetate alone. This will be a critical step for them because, as co-author Robert Jinkerson notes, acetate in large quantities has a tendency to turn a plant toxic.
As well, while plants use can acetone more efficiently than direct light, they still have to work to convert it into carbon, which they will then pair with oxygen and hydrogen to create glucose (C6H12O6). Only after doing that can they create new biomass. That begs the question since there are toxicity issues with acetone in large amounts, is there something better that can skip more steps in the photosynthetic process than it?
And at the end of the day, because there are so many ways in which the energy of biological photosynthesis can be improved upon, the study’s authors believe a combination of biological and artificial photosystems is likely the way forward to suitable gardening.
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