Cash crops grown from desert sands. The seawater greenhouse can do just that. This ingenious concept allows vegetables and fruit to be grown in the world’s most arid regions. It provides low-cost fresh water as well. Seawater greenhouses have the potential to become a game-changer: greening deserts and providing abundant fresh food.
The award-winning idea was masterminded by a London lighting designer more than twenty years ago. The career path Charlie Paton choose has been circuitous, if not tortuous. Mr Paton studied at the Central School of Art and Design. He worked his way through college as an electrician. Subsequently, Mr Paton found employment as a studio assistant. He was there for the coverage of the Apollo 11 moon landing in 1969. Mr Paton went on to become a lighting designer and a special effects guru.
Mr Paton’s interest in photosynthesis was piqued as he tinkered around with special effects lighting. His eureka-moment came while on a steamy bus in Morocco. During a downpour, Mr Paton keenly observed how condensation from his fellow passengers’ wet clothes ran down the windows. That gave him an idea.
The key is to use seawater to cool and humidify the surroundings and thus create an environment where plants need less water, yet grow better. Using only salty water and sunlight, a seawater greenhouse creates ideal growing conditions for crops inside. It also produces fresh water for irrigation.
A seawater greenhouse can cool the air by as much as fifteen degrees Celsius and raise humidity 90% or more. This combination of a lower temperature and higher humidity reduces plant transpiration which in turn enables crops such as cucumber, tomatoes, and lettuce to thrive in deserts.
Seawater greenhouses are ideally located on flat arid land bordering the seashore. Seawater is used for evaporative cooling which raises humidity and lowers the temperature. Water is piped through honeycombed cardboard structures which enlarge the surface area to facilitate evaporation. The concentrated brine which remains as a by-product can be used outside the greenhouse to encourage restorative growth that keeps the desert at bay. The humid air expelled from the buildings creates a zone of higher humidity where vegetation will readily grow, greening the desert in the process.
In 1995, Seawater Greenhouses Ltd, a company founded by Mr Paton, built a pilot greenhouse on Tenerife which produced excellent crops and showcased the potential of the concept. The firm has since designed and built seawater greenhouses in Abu Dhabi, Oman, and Australia.
Each seawater greenhouse is custom-designed to best fit its intended location. Before building begins, exhaustive data on the local micro-climate is gathered: prevailing winds, their force and direction, and the hours and intensity of sunshine are meticulously recorded to establish the greenhouse’s operational parameters.
Mr Paton and his family are committed to promoting sustainable development. Currently projects are underway to produce tomatoes in the Horn of Africa. Somaliland, Somalia, Djibouti, Eritrea, and Yemen have already signed on. Mr Paton points out that these countries are all receiving food aid and may reduce their dependency on foreign donors by growing crops domestically. “Greenhouses in Europe are usually capital intensive due to the high cost of both labour and land. In Africa, these costs are markedly lower. Also, the only energy input required is that of the power to drive the water pumps.”
Other organisations are now displaying an interest in seawater greenhouses as well. The Sahara Forest Project – a Norwegian programme in Qatar that now aims to increase its geographical footprint in the region – and Sundrop Farms in South Australia are built around elaborate seawater greenhouses.
Mr Paton believes that the simple technology he developed may help turn the Sahara Desert back into the forest it was some 6,000 years ago. His focus remains on low-cost schemes which improve sustainability: “I favour simple, economic solutions that deliver the goods. The challenge now is to bring greenhouse technology to places where little to no money is available.”