Everything about Seawater Greenhouse is counter-intuitive. You do not have to know much about agriculture to know you don’t grow things in a desert, you don’t grow things using sea water, and you don’t make your key target markets war-torn failed states.
And yet that is exactly what Charlie Paton, chief executive of Seawater Greenhouse, has done. He might just solve several of the world’s most pressing environmental and humanitarian problems in the process.
The company, which is taking part in this year’s UK Clean and Cool trade mission to San Francisco, has developed a patented greenhouse design that allows farmers to grow crops in arid, desert environments using water extracted from the sea.
Paton describes the system as both “extremely low-tech” and “ultra-efficient”, explaining how a specially designed lattice wall or fence, similar to a “large structured piece of Weetabix”, is added to one end of a conventional greenhouse or polytunnel.
Seawater is then poured over the lattice using a pump, and a fan is directed at the structure allowing the water to quickly evaporate in the hot environment. The resulting fresh water then condenses, cooling the greenhouse and providing water for the plants.
“It is actually much more energy efficient to cool a greenhouse in a desert than heat a greenhouse in Holland or the UK, and we can also deploy solar panels to provide what little energy we need, making the site zero-carbon,” he added. “If you can get this right, in the right place, you can maintain food security and give farmers access to a significant new revenue stream.”
Four separate trials in Tenerife, Oman, Australia and Abu Dhabi have proven the technology works and have even provided some early evidence of positive side effects.
“One of the main byproducts is water vapour, which creates humid air, and we are beginning to see that the greenhouses can have a restorative effect on the arid land down wind,” Paton explained, adding that if deployed at scale the salt extracted from sea water could be used for sea salt or bath salts, while some of the remaining nutrients could potentially be used to create fertiliser.
With its trials successfully completed, the company is looking for investors or customers keen to deploy full commercial-scale seawater greenhouses. “The technology is scalable so costs vary, but about £1m per site would give you a commercial-scale greenhouse, which is not a huge sum by the standard of the industry,” Paton said.
The company has earmarked Mexico as the ideal market for initial expansion, thanks to its agricultural heritage, existing expertise with greenhouses, high levels of food demand, and the fact the country is enduring the worst drought in recorded history.
However, in the long run Paton would like to find some form of philanthropic backer to allow the design to be deployed in countries such as Somalia and Yemen. “A failed state is essentially a state that cannot feed itself,” he said. “There is a strong humanitarian and security case for providing countries with the ability to deliver their own food security, and this design could be part of the answer.”
Seawater Greenhouse was founded in 1999 and has endured several false starts that Paton ascribes to a cultural reluctance to embrace a technology that breaks so many agricultural rules.
“We had a major challenge with the European Commission, which thought we were trying to undermine the Common Agricultural Policy and give North Africa a means to export food to Europe. And there have been cultural barriers in some countries, where there is not a business approach to agriculture and it is widely seen as something only peasants do,” Paton explained. “But we’re hopeful those barriers are beginning to come down.”