Magnificent ice berg view from the Antarctic. Once again the peculiar nature of water is revealed. Two strange properties leap to mind. When water freezes, it expands. And with expansion comes an increase in volume with no loss in mass. The extra volume allows the frozen water, the ice, to become slightly buoyant – in other words ice floats in water.
A second strange freezing property of water is that as the molecules re-align themselves, dissolved ions are pushed aside and expelled. In brief, the ions or salt is no longer welcome and the ice-berg becomes a very large, floating hulk of potable/drinking water.
Is free potable water actually free?
Well we all know that there is no such thing as a free lunch. However, luckily for us, the son’s energy is freely available. With careful and creative harnessing of fossil, wind or solar power, it is possible for large motor driven boats to head south and collect an ice-berg or two. This leviathan task is presently not economically viable and for the foreseeable future it is unlikely that we will be seeing ice-bergs dipping past the Karbonkle berg.
Removal of dissolved salts from the sea water, or any water for that matter, is an energy sapping business. Freezing water to remove salt works and that is good and well if down (or up) at the earth’s poles. Most of the planet’s vibrant and dry life is sustained in a broad belt straddled between the arctic circles. In this zone, freezing water requires so much energy that this simple technology is just not viable. No free potable water in this process.
At the other end of the scale and observed in Robert Boyle’s law, water evapourates at a boiling point. Water molecules that manage to phase shift from water to gas, shed their bonds to clinging and dissolved salts. Over vast expanses of time, this is the process and cause of saltiness in the sea. In the main, salts are locked up or attached to dry-land rock. Salts, obedient to the laws of attraction, preferentially give up their attachments to rock and form tights bonds with rain water. Eventually or rapidly, the rain water, now called ground water, will find it’s way back to the sea, carrying a variable load of dissolved salts. For the salts, the journey ends in the sea. For water, the journey is a continuous cycle from sea to land and back to sea.
