California is currently in its fifth year of severe drought and spends around 80 percent of its fast diminishing water supply on agricultural usage, growing more than a third of America's vegetables and two-thirds of its fruit and nuts. The time has now come for the state to employ new technologies that will significantly reduce the amount of water required to grow food supplies to ensure its continuity.
Dubbed “Ring Garden” the design utilises solar energy to power a rotating desalination plant and farm that produces clean drinking water for the city of Santa Monica while also growing food crops – including algae. Ring Garden is capable of churning out 16 million gallons of clean water, 40,000 pounds of aeroponic crops, and 11,000 pounds of spirulina biomass for livestock feed.
A desalination plant, rotating aeroponics farm, and algae bioreactor in one, Ring Garden is designed to “harvest seawater, CO2, and the sun’s energy to create food, biomass, and fresh water,” according to Predonu’s design brief. The plant is powered by photovoltaic panels that produce 440 MWh each year. 100 percent of that energy is used to power the desalination process and rotate the garden.
“Seawater enters the desalination plant through special screens that protect fish and local wildlife,” he said. “Solar panels power a high-pressure pump to pressurize seawater above the osmotic pressure and through a semi permeable membrane.”
The clean water that results from this process will then be divided among several key areas – 60 percent goes to irrigating the rotating plants, 30 percent would be dispatched to feed the city grid, while the remaining brine water, which would be potentially toxic to marine life, would be re-directed to the bioreactor to cultivate spirulina for biomass.
“The aeroponics system uses 98% less water than conventional farming and yields on average 30% more crops without the need for pesticides or fertilizers,” says Predonu. “Ring Garden demonstrates that the main elements a plant needs in order to grow—water, sun, nutrients, and CO2— are on site and don’t need to be transported. On a footprint of about 1,000 m2 the farm can produce vegetables that would otherwise take 26,000 m2 of land and 340 million gallons of fresh water per year.”
Predonu is confident that if built, his Ring Garden would be able to redirect more than 300 million gallons of water a year to the drought-stricken state, while only needing to use nine million gallons itself.
The Ring Garden concept also allows, and encourages, public interaction. Visitors would be encouraged to visit and pick vegetables from the aeroponics garden as well as providing the ability to learn more about sustainable innovation from an on-site Eco Awareness Centre.
The fate of Predonu’s Ring Garden will be decided when the winners of Land Art Generator Initiative are announced at Greenbuild in October 2016.