Water is likely to be a big problem as the world tries to meet future demand for food. By 2050, we could need 60% more calories than we produce today. And yet, many parts of the world are already running short of freshwater necessary to grow crops (70% of all freshwater goes to agriculture).
That’s what makes the Sahara Forest Project interesting. Its saltwater greenhouse uses half as much freshwater as conventional greenhouses, and it could allow water-poor countries to grow food more sustainably while reducing the need for food imports. It could even help re-vegetate deserts in some countries.
The greenhouse has a cardboard screen at one end with hundreds of small holes in it. Saltwater trickles down from above and evaporates as it meets hot air coming in from outside. The air indoors becomes humid and up to 15 degrees Celsius cooler than normal, while the moisture condensates on the plants, helping them to grow.
At the same time, the greenhouse also has a series of pipes full of cold ocean water. When warm air hits the pipes, droplets form on the surface, which are captured and used for irrigation.
The most innovative aspect is the way the greenhouse is integrated with a concentrated solar system outside. The sun heats water so it becomes steam and turns a turbine to generate electricity. That powers the plant’s pumps as well as a desalination unit that produces more freshwater. In turn, the waste brine from the greenhouse helps cool the solar system, improving efficiency by up to 10% compared to a typical plant.
The idea was born in northern Europe but is most likely to be applied in hot, desert regions. Last year, SFP ran a successful pilot at a site in Qatar, in the Gulf. It’s now at the early stages of building a full-scale facility in Jordan, with funding partly coming from theNorwegian government (SFP is based in Norway).
“Many of these arid areas have substantial water and food security issues,” Hauge adds. “Jordan is the fourth poorest country in the world when it comes to freshwater resources. So, it really makes a lot of sense to utilize other ways to achieve agricultural activity.”
The pilot showed that just eight hectares of greenhouses could produce all the cucumbers, tomatoes, peppers and eggplant Qatar consumes in a year. Currently, the country imports 90% of its produce from abroad.