Desalination: the quest to quench the world's thirst for water
Population growth is one factor, not only the need for drinking water and sanitation but also the need to produce more food. Agriculture accounts for 70% of water use.
Even the push for biofuels to reduce consumption of fossil fuels has an unexpected consequence: between 1,000 and 4,000 litres of water are needed to produce just one litre of biofuel.
While reducing consumption is one way of helping to address the water crisis on an individual level, it is far from the complete solution. Something on a larger scale is also needed: desalination.
Desalination is also used in some greenhouses. The amount of salt being that can be removed is between 70% and 90%. It requires a lot of energy – although Philip Davies, reader in mechanical engineering and design at Aston University in Birmingham, has devised a system of solar power to keep usage to a minimum.
The academic is also involved in a project in Somaliland, which faces the twin challenges of rapid population growth and limited water resources. It is one area using seawater greenhouses, which produce water for irrigation by pumping seawater into the greenhouse and piping it over honeycomb cardboard pads that provide a large area for evaporative cooling.
According to Charlie Paton, who founded Seawater Greenhouse Ltd two decades ago, a seawater greenhouse cools the air by up to 15 degrees and increases humidity to as much as 90% even in some of the world’s most arid places. Davies says they can reduce the amount of water needed to produce a kilogram of produce from hundreds to tens of litres.
Researchers continue to seek to improve the technology behind reverse osmosis.
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