The elixir of life
EarthHour 2010 has come and gone. It reminded us about many things but one item that slipped a little below the radar screen was the critical issue of water. Not only what water we use, or more importantly what water we don’t use, but where does our water come from?It is presumably not necessary to remind Bolanders that water in this part of the world is in terribly short supply, and the predictions are that it is going to get a lot worse. Perhaps the recent drought in the George area is a portent of what is to come.
We need to be aware of the reality so that we are able to deal with it effectively. It simply cannot continue on the basis of business as usual!
On this occasion, instead of only discussing our current water situation and usage, I thought it would be useful to give some consumption indicators and then discuss what the world is doing about dealing with water shortages.
Consider the following:
Each of us drinks about two litres of water a day in various forms; up to 100 litres when we shower, and more if we bath; the food we eat probably uses about 2 000 litres to be produced; 1 kilogram of cotton requires somewhere between 7 000 and 29 000 litres of water before it becomes a T-shirt on your back; a sheet of paper uses up about 9 litres in production; and so on. We simply cannot survive without water. One can survive far longer without food than without water.
It is a very challenging paradox for us 6,5 billion people. Two-thirds of our tiny planet is covered with water and only about 1% is fresh and drinkable. The rest is inaccessible and unpalatable because of one main ingredient: salt!
Building big dams is not the long term answer. They are expensive, cause huge downstream problems and often reduce the amount of free water available for usage in the long run. In addition, construction of infrastructure for these huge dams is massively costly and the maintenance once built is astronomical.
Many countries are now investing heavily in desalination as the way of the future. Desalination plants can be built closer to the populations they serve. Many millions of the world’s populations live on or near the coast which simplifies the supply chain considerably.
Perhaps one of the most important factors contributing to the growth of desalination as a water supply solution for the future is that the price and effectiveness of desalination has made this a realistic and affordable option.
Countries as diverse as Saudi Arabia and Spain are investing heavily in desalination plants in order to meet their water needs. Given that the world’s water scientists are predicting wide-spread shortages by the year 2025, and that South Africa is predicted to be among the worst affected, perhaps we should be going this route now before the crisis hits us.
One of the factors contributing to the reduction in desalination costs is the emergence of new osmosis-based technology. Old-style desalination plants use energy-intensive evaporation as the core technology. Latest desalination plants are using reverse osmosis, a much cheaper and more effective option to produce potable water. The normal flow of osmosis sees fluids, in this case water, flowing from the lower concentration side of the membrane to the higher concentration.
The new technology reverses this flow by applying pressure on the side of higher concentration, forcing the water through especially designed membranes, leaving the unwanted chemicals and metals behind. Once these are removed, appropriate chemicals like chlorine are added to make sure that the water is pure enough to drink.
It all sounds quite simple but the technology used is advanced. Price and water scarcity is driving technological innovation, and this in turn will bring the price down even further.
The good thing is that big companies like General Electric, from countries as diverse as America, France, Spain, Italy and South Korea are investing resources to develop this technology further and faster. If these companies are doing so it is because they are betting on the future, and the future is sea water!
The old song about seawater and “not a drop to drink” is no longer true – we may well be drinking it sooner than we all thought was possible.
Written by Tony Frost You are reading The elixir of life articles
