The underwater farm is owned by Sergio Gamberini, a professional scuba diver and amateur gardener from Liguria, a coastal region in north-west Italy. The farm is named “Nemo’s Garden,” counts six underwater greenhouses hosting an estimated 700 plants including basil, tomatoes, salad, strawberries, aloe vera, mint, marjoram, and liquorice.
“At first we designed semi-spheres made of Polyvinyl Chloride (PVC), a common thermoplastic material, that was very light and could be easily removed,” says Nemo’s Garden Project Manager Gianni Fontanesi. But after the first winter storm, when waves between nine and thirteen feet uprooted two of the underwater structures, the team opted for a different strategy.
“We now use rigid plexiglass with an internal and external steel skeleton,” Fontanesi explains, adding that finding the right design to prevent storm damage has been the greatest challenge to date. The semi-spheres are six feet wide and three feet high, and are attached to the seafloor with 28 (removable) screws. According to Fontanesi, this design ensures stability while allowing enough oscillation to prevent wreckage when waves hit.
Next, the team had to figure out the science of underwater farming. Most light is provided by natural sunlight. “We get 70% of sunlight compared with surface levels,” Fontanesi explains.
During winter months or cloudy days, artificial light from LED lamps placed inside the spheres supplements the natural light. This electricity comes from solar panels and a small wind turbine onshore, which is fed to the greenhouses, along with water for irrigation, via a system of tubes shaped like a double helix.
For now, the project requires fresh water from land. But as Gamberini explains, the long-term goal of Nemo’s is to harness the natural desalination process that takes place in the greenhouses.
This would take advantage of the fact that the greenhouses are not entirely sealed. The bottom has a breach—used by divers to access the plants—that lets ocean water in. This does not mean that the entire biosphere is flooded. Much like in a bottle submerged underwater, water fills only part of the structures. Air pressure keeps it at bay, leaving the upper part dry.
Gamberini and Fontanesi can monitor the temperature, air composition, and energy use from the project headquarters in Genoa, Liguria’s main city. But farming is done by visiting the greenhouses in person. To date, Fontanesi has logged nearly a thousand “farming dives.” He says it feels like being in an aquarium turned inside out. “You are the fish looking out into the outside world.”
So far, the most surprising discovery regards underwater plant chemistry. Plants grown 22-feet below sea level face double the amount of atmospheric pressure compared with their counterparts on land. This, according to Fontanesi, has led to a different distribution of chemical elements.
But the ultimate goal of the project remains to turn underwater farming into a viable option, especially in areas where water scarcity is an issue. “Eventually we want to create a system that is cost-efficient and energy-sufficient to offer a sustainable alternative to land farming,” Fontanesi explains. That will take years, at a minimum. But if he succeeds, a wetsuit and scuba tank could become as standard for farmers as overalls and tractors.
According to atlasobscura