Growing rice in a pitch-dark basement in the city, or growing tomatoes and lettuce in a spaceship or on Mars. According to American researchers, this is possible with a new technique. It is even more efficient than conventional farming. “Less land is needed.”
The method, published last week in the scientific journal Nature Food, skips the step of photosynthesis in crops. This is the process by which plants use sunlight to convert CO2 and convert water into building materials they need to grow. They do not do this very efficiently: often only about one percent of the available energy from sunlight is converted into biomass.
That is why scientists worldwide are pondering the question of how photosynthesis can be ‘stepped up’. Higher efficiency results in a higher yield of crops, so that less agricultural land is needed for the same amount of food. While some researchers focus on improving the plants via genetic modification (with only limited production gains for the time being), the American research group opts for an alternative route, which does not require sunlight.
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Acetate method
Instead, electricity is used to generate CO2 and converting water – through a process called electrolysis – into acetate, the main component of vinegar. Like the sugar produced by photosynthesis, organisms can use this stuff as an energy source to grow.
Experiments show that this is done more efficiently than in ‘traditional’ agriculture. When the electricity comes from solar panels, a larger part of the energy from sunlight is converted into biomass.
For example, yeast, normally fed by sugars from maize, was found to grow 18 times more efficiently using the ‘acetate method’. In addition, the team found that a large number of crops, including tomatoes, lettuce, rice and peas, are suitable for growing in a dark room via acetate.
CO2 filter out the air
A beautiful and original study, says Huub de Groot, professor of biochemistry at Leiden University and not involved in the research. ‘It was already known that organisms can grow on acetate, and also that this stuff can be produced via electrolysis. Yet it is an innovative idea to combine those two steps in this way. With these results, a whole new field can be explored.’
Although De Groot does believe that the process is less efficient than the researchers make it appear. ‘Plants filter CO . themselves2 from the air, while it is supplied here in concentrated form. The step before, removing and concentrating CO . from the air2, takes energy. They don’t seem to have counted that now. Incidentally, there are quite a few sources of concentrated CO2 available, for example from the industry, which you can use for this.’
The research group sees a whole range of new possibilities by ‘liberating’ agriculture from complete dependence on sunlight. “Using this technique could represent a paradigm shift in the way we feed people,” Robert Jinkerson, a chemist at the University of California, said in a press release. ‘Due to the increased efficiency, less land is needed, which reduces the impact of agriculture on nature.’
Fresh tomatoes on Mars
Because the crops grow in a controlled environment, they are also less vulnerable to the consequences of climate change, such as drought and flooding. And for the purchase of suitable agricultural land, because with the method food can also be grown in less common places, such as in (dark) buildings in cities.
Which, incidentally, could also be useful for future space travelers, the researchers note. The limited space required and independence from sunlight means that the technology can potentially also provide fresh tomatoes or lettuce in a spaceship or on Mars. “Whereas the increased efficiency helps to feed more crew members with less input,” said Jinkerson.
An additional advantage is that known crops can be produced with this method without many adjustments, notes De Groot. ‘The head of lettuce or rice on the plate remains the same. You do not intervene directly in the DNA of the organism, and the crops still grow in a natural way. It is very different from, for example, cultured meat.’