seawater greenhouse project sheet

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					                                                                                      9 May 2007

    The Seawater Greenhouse – Fresh Water From Thin Air
“The Seawater Greenhouse is a truly new idea which has the potential to impact the lives of
millions of people living in coastal, water-starved areas around the world,” says Marco
Goldschmied, architect and former President of the Royal Institute of British Architects.

The latest news from programme director, Charlie Paton

A shortage of water, and the inability to grow crops, is the root cause of much suffering and
poverty in the world today. Over one billion people do not have access to a safe supply of
water and that number is increasing. As demand outstrips supply, the depletion of ground
water is accelerated, causing saline intrusion in coastal regions and thereby reducing further
the ability to grow crops.

None of the methods currently used to supply irrigation water in arid regions, including over-
abstraction from ground reserves, diverting water from other regions and energy-intensive
desalination, are sustainable in the long term.

The Seawater Greenhouse, designed to provide a cost-efficient and sustainable solution,
distils fresh water from seawater and cools the growing environment. This creates optimum
conditions for cultivation, enabling crops to be grown where otherwise it would be difficult, or
impossible. Cooler and more humid conditions enable crops to grow with very little water.
Crop yield and quality is also increased because crops are not stressed by excessive
transpiration. In Oman, one of the hottest countries on earth, the daily outdoor irrigation rate in
winter is four litres per square metre, increasing to 11 litres per square metre, in summer.
Inside the Seawater Greenhouse, these rates are substantially reduced to a range of 1 - 1.4
litres per square metre. This represents a four to eight-fold saving and shows that part of the
solution to the world’s water shortage may be to create conditions that use less water and at
the same time grow better crops.

The Seawater Greenhouse uses very little electrical power compared with conventional air
conditioning and desalination processes, because the energy for cooling and distillation is
provided by the sun and wind directly. As the modest demand for electrical power for fans and
pumps is proportional to sunlight, we propose in future to meet this need with photovoltaic
panels, without the need for batteries and inverters. In addition to carbon dioxide savings, this
will enable off-grid, and remote communities, to produce crops and fresh water.

Conventional greenhouse operations frequently have environmentally damaging
consequences, primarily through over-abstraction of water and over-use of pesticides. In
Almeria, the most arid region of southern Spain, damage is particularly severe. This region
alone has 20,000 hectares of greenhouses, which accounts for 10 per cent of greenhouse
coverage in the Mediterranean basin as a whole.

However, our seawater evaporators, through which all ventilation air must pass, are very
effective at removing airborne contaminants, including salt spray, dust, pollen and insects.
This ‘air scrubbing effect’ is such that in all our pilot greenhouses to date, we have never had
to use pesticides.

We now plan to develop specific solutions for the Mediterranean region, where both the use of
groundwater and pesticide will be reduced or eliminated.

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For downloadable photographs see next page.