Water of Life

A clever design showing the word H2O drawn in condensation water droplets.An Essential Molecule for the Sustainability of Life

Water.  H2O.  The chemical formula is simple.  Two atoms of hydrogen H and one atom of oxygen O, held together by covalent bonds, are all it takes to make what is perhaps the most fundamental substance to life on Earth. 

Tasteless and odourless.  Water is a major component of living organisms.

Our most essential body functions depend on water-based fluids.  Plant life also depends on regular supplies of water for their growth.  Clearly, water is essential to life, and without it there would be no life.

This means that population densities are much higher where there are plentiful supplies of water.  People who do live in desert areas are very few, unless sufficiently abundant sources of water are available that can be brought from outside the arid regions.  So, people don’t live in deserts… but cacti and camels do.

 

People don’t live in Deserts

To survive in deserts, organisms must be able to manage without water for long periods, while minimising water loss from their surfaces.  Cacti are very efficient at storing water, and use an extensive network of shallow roots to absorb water or moisture before it has a chance to evaporate into the atmosphere.  Their surface layer is exceptionally waterproof.  Camels can quickly replace lost water by drinking enormous quantities and store fat reserves in their humps, which in turn can be broken down and released as water.

By comparison, human are not designed to resist such hostile environments.  Humans beings (and mammals) sweat in order to cool off and maintain their body temperature to a reasonable level.

Most of the water released by that process comes from their blood.  If lost water is not replenished, a major problem ensues: the blood becomes too viscous, and the heart struggles to pump it around the body.

 

Global Consumption of Water

Global water use has increased over the last century.  However, this is not merely due to the increase of the world population, but it depends increasingly on the fact that we now use water in a wide variety of ways.

Water plays an important role in the World economy: it is used as a solvent for a range of chemical substances, and in industrial cooling and transportation.  Approximately 70% of the fresh water used by humans goes to agriculture, according to Baroni et al. (2007).

 

The World’s Water Footprint

 

A map showing the average World water footprint.
Average Water Footprint of National Consumption in m3 per Year per Capita between the Years 1996-2005. Source: Mekonnen and Hoekstra (2011)

The water footprint of national consumption is defined as the total amount of fresh water that is used to produce the goods and services consumed by the inhabitants of the nation.

Countries with a water footprint that is smaller than the global average are shown in green in the map; countries shown in yellow-red have a water footprint larger than the global average.  There are broad differences between countries.  In the USA, the average water footprint is 2,842 m3 per year per capita.  In China, the average water footprint is almost three times lower with just 1,071 m3 per year per capita.

At the low end of the range, the United Kingdom has a water footprint of 1,258 m3 per year.

There will be important seasonal variations in domestic water usage.

When droughts lead to water shortages, dramatic changes to the levels and patterns of water use occur.  A total of around 604 litres of water are estimated to be used each day in the UK per head of population.  That’s right, over 600 litres of water!

 

Life in the developed world has become dependent on plentiful supplies of clean water being readily available on tap.

 

A photograph showing two hands forming a cup to receive quality drinking water,

Although access to safe drinking water has much improved over the past decades almost everywhere in the World, one billion people still lack access to safe water and over 2.5 billion do not have access to adequate sanitation.  As a Westerner, this is giving me one heck of a guilty conscience!  

A clear correlation exists between access to safe water and GDP (Gross Domestic Product, i.e. the total market value of all final goods and services produced by a nation in any given year) per capita.

A report, published by the 2030 Water Resources Group in 2009, suggests that by the year 2030, water demand will exceed supply by 50% in some developing regions of the World…

 

Liquid, Solid and Gas: Three States of Water

 

When water plays its most important role for living organisms, it is in its liquid form.  Around 71% of the Earth’s surface is covered in water, be it as oceans or seas.

A diagram illustrating the different physical states of water, from melting to evaporation, and from condensation to freezing.Changing the temperature of a substance like water can lead to a change of stateChanging the pressure of a substance can also lead to a change of state.  We will discuss this later in greater details when I introduce the all-important Equation of State:

PV = nRT

Again, stay tuned on this blog!  🙂

Of course, there is plenty of evidence of water as a solid on Earth in high-latitude regions, like the polar ice caps, where the temperature descends below zero degree Celsius.  Here in Scotland, and other countries of the Western hemisphere, we often experience winters when water, and precipitations, freeze into the form of snow or ice.

 

Cold air cannot hold as much water vapour as warm air.

 

Boiling a kettle imparts heat to liquid water, and if enough energy is transferred, water undergoes a process of vaporization.  At this point, liquid water turns to gas in the form of invisible steam, or water vapour.  When steam cools down, the tiny water droplets suspended in the ambient air condenses back into its liquid state.  Condensation of water on cold objects, like a cocktail glass, is evidence for the presence of gaseous water in air.  Mist, fog, clouds, rain and snow are also familiar consequences of the presence of water vapour in the air.

 

Water as a Source of Energy

Water has long been used as a source of renewable mechanical energy to generate electricity.  But what if you could actually use it as a fuel?

In 1989, cold fusion gained international media attention after reports by Stanley Pons and Martin Fleischmann, two of the world’s most distinguished electrochemists, that their laboratory apparatus had produced an anomalous amount of heat (i.e. “excess heat”), of a magnitude they asserted would defy all explanation, except in terms of nuclear processes.  Pons and Fleischmann further reported measuring small amounts of nuclear reaction by-products, including neutrons and tritium. The small tabletop experiment involved electrolysis of heavy water on the surface of a palladium (Pd) electrode.

Many research groups tried to reproduce the Fleischmann-Pons experiment, without success.  As a result, the Fleischmann-Pons experiment was discredited at the time, and the reputation of the two scientists suffered greatly. 

Today, cold fusion research is hotting up again with several international physics teams detecting that anomalous excess heat is indeed being produced by their independently-run experiments.  Research funding is beginning to flow into cold fusion again.  This renewed interest into the phenomenon could quite simply lead to the Holy Grail of energy production.