We first heard about hydroponics as a solution for growing food in the Atacama Desert, the most arid desert in the world, when we left Vallenar. Hydroponics is a technique for growing crops without soil, on an inert mineral or vegetable substrate, irrigated with a nutrient-containing preparation. Our host Omar Turres, while showing us around his experimental hydroponic farm (see the report "Chile after the COP"), told us about this cooperative that produces vegetables and fruit above ground using desalinated water, on the outskirts of Antofagasta.
We went there on a Saturday morning and as luck would have it, it was precisely on weekend mornings that the cooperative of the Agricultural Association of Altos La Portada (AGRALPA) sells its produce to customers on site. In addition to taking photos, we were able to visit two of the structures, once with Walker, a Bolivian agricultural technician, and once with Dolores Jiménez, president of the cooperative, who answered our questions and allowed us to sleep in the association's meeting room. The next day we went to Mejillones, about 40 km away, to document another so-called "sacrificed" area (see again the report "Chile after the COP"), before returning the following day to photograph the desalination plant in the city of Antofagasta that supplies water to this hydroponic project.
The desalination plant is part of the company Aguas Antofagasta, which belongs to the group epm (Entreprises Publiques de Medellín), a state-owned company in Colombia. It uses the reverse osmosis technique, sometimes called hyperfiltration, to purify water. This is a membrane process: semi-permeable membranes extract fresh water from salt water by means of high pressure. After being filtered and desalinated, the water must be remineralised before being delivered to the city. In other remineralisation filters, it is recharged with sodium hypochlorite, calcium hydroxide and sodium floride. During the visit we learn that Antofagasta is supplied with 80% of its water by the desalination plant and 17.5% by water from the Cordillera, and that Mejillones, from where we arrived, is the only city in Chile supplied with 100% desalinated water.
Later we read in the press that a desalination plant is a large consumer of energy and that when it produces 1 litre of fresh water it releases 1.5 litres of brine; this concentration of salt disrupts the ecosystems and increases the temperature of the water. This technology, which appears to be a response to the decline in water resources, therefore has an environmental impact.
To go further on the subject you can read these articles:
https://www.geo.fr/environnement/chili-faire-pousser-des-legumes-dans-le-desert-le-plus-aride-du-monde-195023
http://www.indap.gob.cl/noticias/detalle/2016/12/20/altos-la-portada-ganándole-al-desierto-con-la-ayuda-del-mar
https://www.la-croix.com/Economie/Monde/usines-dessalement-produisent-saumure-deau-douce-2019-01-16-1200995863
https://www.partagedeseaux.info/Enjeux-environnementaux-et-economiques-du-dessalement-de-l-eau
(All these links were consulted on 24 March 2021)
We first heard about hydroponics as a solution for growing food in the Atacama Desert, the most arid desert in the world, when we left Vallenar. Hydroponics is a technique for growing crops without soil, on an inert mineral or vegetable substrate, irrigated with a nutrient-containing preparation. Our host Omar Turres, while showing us around his experimental hydroponic farm (see the report "Chile after the COP"), told us about this cooperative that produces vegetables and fruit above ground using desalinated water, on the outskirts of Antofagasta.
We went there on a Saturday morning and as luck would have it, it was precisely on weekend mornings that the cooperative of the Agricultural Association of Altos La Portada (AGRALPA) sells its produce to customers on site. In addition to taking photos, we were able to visit two of the structures, once with Walker, a Bolivian agricultural technician, and once with Dolores Jiménez, president of the cooperative, who answered our questions and allowed us to sleep in the association's meeting room. The next day we went to Mejillones, about 40 km away, to document another so-called "sacrificed" area (see again the report "Chile after the COP"), before returning the following day to photograph the desalination plant in the city of Antofagasta that supplies water to this hydroponic project.