Seawater Greenhouses

For those who’ve come to my talks and classes you’ll know that I’m a passionate advocate of Seawater Greenhouses, yet this is the first time I’ve written about them on this blog. They are one of the game-changing technologies that form part of the interconnected web of solutions to our global web of problems: Climate Change, Ocean Acidification, Peak Oil, Hunger, Poverty, Loss of biodiversity, Soil Erosion, Water Shortage etc.
The Seawater Greenhouse offers one of the most revolutionary and hopeful technological innovations for ecologically restorative agriculture in the hot arid zones of the world, especially those near the coast. The Seawater Greenhouse process is relatively straightforward: seawater is poured down a cardboard lattice at one end of a plastic greenhouse, while hot dry desert air is blown through the lattice, evaporating the water and leaving the salt behind on the lattice. The now cool moist air makes an excellent growing environment within the greenhouse. Before this moist air leaves the greenhouse it hits the cold surface of plastic pipes filled with flowing cold deep-seawater, where the vapour condenses. The amount of fresh water created in this way is greater than that needed to irrigate the crops growing in the greenhouse, leaving a surplus for irrigating outside orchards or supplying local communities with fresh water.
Charlie Paton thought-up the idea in 1991 and the first trial project was built in Tenerife in 1992. The concept was proved to work and two further research greenhouses were built, one in Abu Dhabi in 2000 and then one in Oman in 2004. The first commercial horticultural seawater greenhouse project has been built near Port Augusta in South Australia and produced its first crop of tomatoes a couple of months ago.
Seawater Greenhouses and Concentrating Solar Power will have synergistic benefits when developed together, and offer the scope for further beneficial uses of the water and electricity so created; surplus water can be used to grow trees and crops outside the greenhouses, develop algae biofuels and aquaculture, sell electricity, horticultural produce and possibly a wide range of other produce including algal bio-fuels. Charlie Paton and his colleagues have researched the possibility of this wider integrated development for some time and use the term “The Sahara Forest Project” to describe this process, which could of course be adapted to a wide variety of desert locations. It has just been announced that the first of these larger scale integrated developments is to be built in southern Jordan, near the port of Aqaba. At this time of political flux in North Africa and the Middle East this is just the kind of ecologically restorative project that offers the hope of sustainable prosperity for the people of the region. I wish this project well, and will follow developments on this blog.

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