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Image of an area suffering from salination problems. Image of Shakespeare quote

Introduction

When the sea is evaporated to form water vapour, the sea does not boil. The sun, assisted by the wind, bounces water molecules into the air, many of which move to high altitude, carried up by the lower density of water vapour compared with dry air (see Graph 1). When water condenses to form clouds and rain, there is no compressor operating, no refrigeration system The main factor is simply a fall in air temperature so that the air can contain less water vapour (see Graph 2). The MAXWATER seawater distillation system is modelled on these natural processes, uses natural renewable energy sources and is environmentally neutral or restorative.

Sunlight provides more than 1 kilowatt of energy per square metre over most of the populated surface of the world. This energy can be used to increase the evaporation of salt water in such a way that distilled water can be recovered. Wind provides a huge amount of energy, with air frequently moving at more than 20 kilometres per hour. This energy can be used to move water vapour to a cool area where condensation can occur and can assist in the movement of water. The energy from both these sources is intermittent but vastly more dependable than rainfall

The sea has an area of 71% of the Earth's surface and an average depth of around 4 kilometres. The construction of a rainwater reservoir on this scale is inconceivable. Existing reservoirs are of relatively minute dimensions yet their construction has been achieved at vast cost and the effect on the environment has generally been devastating. It is increasingly recognised too that the use of rivers as a source of water for irrigation is rapidly leading to degradation of the rivers with impaired flow and increasing pollution of the water. When these factors are taken into account it should be apparent to even the most sceptical that, not only is the use of the sea as our reservoir of water inevitable for our survival, but it is more socially cost effective than rainwater.

Even the installation of vast solar distillation systems sufficient to provide a reliable water supply to all the people on earth would have no deleterious effect on the quality of seawater or the hugely important ecosystems of the sea. Such a radical change would remain a miniscule fraction of the normal process of evaporation of water from the sea to generate rain. On land however, rainfall would increase in currently dry areas due to the increase in vegetation. There are two caveats: firstly, the return of concentrated seawater to the sea must be dispersed and directed away from sensitive areas such as coral reefs, so that returning water will rapidly reach the same concentration and properties as the rest of the sea, and secondly, vast restoration of natural deep rooted vegetation must be actively undertaken.

The need to begin constructing systems which provide an adequate supply of fresh water for the world is urgent. It is estimated that 1.3 billion people do not have access to pure water and a further 3 billion people are intermittently afflicted by severe water shortage due to drought. And a similar number have been driven to rely largely on underground water supplies which are already severely depleted and increasingly contaminated with salt, arsenic and other impurities. These numbers, already alarming, appear likely to rise rapidly in the next two decades. Current worldwide efforts to tighten water management may help delay the approaching crisis but would seem to be not only inadequate but an absurdly inappropriate response. The one feature of the various proposals now being discussed which will remain relevant and important is that which aims to limit the flow of pollutants such as nutrients and micro-organisms from populated areas into the sea.