Rising world population and global warming are putting serious pressure on the food system and water resources.

According to an estimate by the World Health Organization, by 2025 half of the global population will live in areas subject to water stress, where the demand for usable water will exceed that available, putting the survival of millions of people at risk.

What if there was an infinite source of water that we could use for agriculture, thus increasing food production without further affecting planetary resources? According to many innovators, the solution to the water problem has always been there, at our disposal: sea water!

Seawater greenhouses

The idea is to use what we have in abundance to produce what we need. Deserts, salt water and sunlight are then used to produce food, water and clean energy.

The seawater greenhouse , designed by the British inventor Charlie Paton, is a plant where, through an innovative solar-powered desalination system, the sea water, conveyed directly from the sea, is used to cool and humidify the air, while the water vapor produced by solar heating is distilled to produce water.

This system allows to maintain a temperature inside the greenhouse up to 15 ° lower than the external one, recreating the ideal conditions for the growth of different varieties of fruit and vegetables. The water requirement is reduced by 90% and, if a greater quantity is needed, desalinated marine water is used.

Another particularly interesting aspect is that the residual water vapor creates an oasis effect even outside the greenhouse, making it possible to revegetate the surrounding areas. "We want to green the desert," says Stake, head of the Sahara Forest Project. "The larger areas we can green, the more carbon we store in the soil." In this. so greenhouses can become a fundamental link in an even more ambitious project, which aims at the reforestation of entire desert areas, primarily the Sahara.

The results are promising

In Port Augusta, in the South Australian desert, is Sundrop Farms, a salt water greenhouse that produces 17,000 tonnes of tomatoes per year, thus covering 13% of the Australian market. The structure is completely autonomous from an energy point of view thanks to 23,000 solar panels, which allow it to produce the energy needed to desalinate seawater.

The advantages are numerous:

- Plants are grown on raised floors, making this crop possible virtually anywhere

- There is no need for any type of pesticides (nothing harmful can enter the greenhouses)

- No fossil fuels are used (self-produced solar energy covers the entire requirement)

- The only water used is that coming from the Gulf of Spencer, or directly from the ocean

- The production is continuous: in the warmer months the desalinated water keeps the greenhouse cool, allowing the growth of tomatoes, while in the colder ones, the structure is heated thanks to the sun's rays.

All these elements make cultivation in seawater greenhouses extremely resilient to all types of external conditions, avoiding various problems of today's agri-food industry, one above all the volatility of prices.

During the last decade, seawater greenhouses have been built in Somalia, Jordan, Oman, Tenerife and Abu Dhabi. All these areas are extremely arid and largely depend on imports of foreign agricultural products, often at not very advantageous conditions. This type of innovation can represent the starting point of a path towards greater internal production, which has always been limited due to the scarcity of water resources and poorly fertile soils.

Seawater greenhouses are one of the most effective weapons at our disposal to avert a global food crisis. To date, 80% of fresh water is used for agriculture and with a population of 10 billion expected in 2050, urgent action is needed to reduce this consumption. The concept of arable land will necessarily have to expand to include deserts and the driest areas of the planet. These could become the key to a more sustainable and equitable food system.

Sources:

- https://www.lifegate.it/serra-acqua-marina-contro-cambiamenti-climatici

- https://www.bbc.com/future/bespoke/follow-the-food/the-people-creating-an-oasis-with-seawater.html

- https://www.green.it/sundrop-farms/