Nearly fifteen percent of all land on Earth is currently used for arable farming. We are expected to feed ten billion mouths by 2050 – two billion more than today. Do we need to cut down more forests for that? Growing more food per square meter may be a more sustainable idea. Better varieties, measured fertilization and control of plant diseases help, but there is an alternative: higher up. By growing crops compactly in tall buildings, cultivation takes up ten to twenty times less land. And it may not even be necessary to hang lamps, according to American research.
Disconnecting solar energy
Normally, a plant uses sunlight for its growth, during photosynthesis. The plant takes water (H2O) from the soil and carbon dioxide (CO2) from the sky. Under the influence of (sun) light, these substances are converted into oxygen (O2) and sugars. Sugar is food for the plant. The oxygen that the plant produces is released into the air.
–
–
–
–
–
–
But plants need light to grow, right? Indeed, they need light for photosynthesis, the process by which they produce CO .2 and convert water into sugars for their growth. Artificial light is a possibility, but lamps consume enormous amounts of electricity. American scientists have recently found a trick that makes plants no longer need light at all.
The researchers bridged the first of the two steps of photosynthesis. That is the only step that requires sunlight: the plant then converts solar energy into chemical energy. In the second step, the plant converts that chemical energy into sugars, which does not require light energy. In the new trick, biologists feed the chemical energy in the form of liquid directly to the crops, eliminating the need for sunlight.
The nutrient that the scientists give the crops, acetate, must first be made in the lab, from CO ., among other things2 and water. This is done with electricity generated by solar panels. The acetate then converts plants into sugars for growth. In this way, the researchers grew algae and clumps of tissue from lettuce. The next step is to grow a full head of lettuce or other crop.
It seems pretty cumbersome at first glance, using the electricity to mimic the first step of photosynthesis, rather than using it for artificial light. But solar panels convert sunlight into energy much more efficiently than plants. Plants use only one percent of all the solar energy they pick up for their growth. With the new method, this is up to four times more. Although those solar panels still have to be produced first, of course.
The energy savings through the diversion of photosynthesis has a chemical reason. “Normally, plants stick six individual carbon atoms, originating from CO2, together to form a larger sugar molecule”, says Sylvestre Bonnet, professor of photochemistry at Leiden University. “The new method makes it easier for plants: the scientists feed the plant building blocks that consist of two carbon atoms. Plants then only have to stick three building blocks together, which saves energy.”
colorless
–
Strawberries grown in the dark will not have an appealing red color because the plant will not make certain pigments.
–
–
–
–
–
–
Yet sunlight does more than just ensure growth. It stimulates the production of green pigment in the chloroplasts, where photosynthesis takes place. If you place a houseplant in a corner that is too dark, the leaves will turn yellow. The same happens with crops in the dark. “The production of other pigments that give plants red, blue or purple colors is also strongly stimulated by light,” says Wageningen food chemist Wouter de Bruijn. Without light we therefore do not get beautiful red strawberries or purple aubergines, but less attractive yellow-white varieties. It is also not yet known whether the taste, texture and quality of food grown in the dark is the same as that of crops as we know them today.
Leo Marcelis, professor of horticulture and product physiology at the University of Wageningen, may have a solution for this. He thinks the new technology could perhaps be used as an aid to existing indoor farms. On such farms – or vertical farming – growers grow crops with LED lighting and simply regulate growth factors, reducing the need for water, fertilizers and pesticides. The major disadvantage of traditional vertical farming is the fact that the LED lamps consume enormous amounts of electricity. “With the new technology, we might be able to grow crops at lower light intensity, so that much less LED lamps are needed,” says Marcelis. This saves purchase costs and electricity, while color, texture and quality are probably preserved.
Featured by the editors
–
Astronomy
Sun, sea and science
–
–
–
Biology
Expedition to melting land
–
–
–
Humanities
Scribbles in the margin tell great stories
–
–
–
–
–
Keep exploring routes
Nevertheless, we should not aim all arrows at one method, say the Dutch experts. “We can improve arable farming through multiple routes and it is always beneficial to explore them at the same time,” says Marcelis. His colleague Lucas van der Zee adds: “The research by the American scientists is still new. It’s an interesting issue, because scientists have been trying to improve photosynthesis for decades. Perhaps growing plants in the dark is the future, but additional research is needed first.”
Sunlight currently forms the basis of our entire food pyramid. With this new technique we may be able to circumvent this basis in the future and thus produce more food on less land. Who knows, our global consumption may then be in line with what the earth can provide.
–
