An increasing world population, salinization of agricultural land, intrusion of seawater into aquifers along coastal areas together with contamination of ground and surface waters have created an urgent demand for alternative fresh water solutions since the second half of the last century. At present over one billion people do not have access to clean and safe drinking water. By 2025, at least three billion people are expected to face severe water shortage. This is one of the most important international issues facing the world today as the earth’s pure drinking water supplies are rapidly disappearing. So water is the “New Oil” or “Blue Gold,” as it is being called.
Water scarcity will also pose a major challenge to businesses, large and small, as global water demand is expected to increase by 55 per cent by 2050, due to manufacturing industry, electricity generation and households. At the same time, land irrigation already the largest consumer of water (60-70%), has to be maintained at least at the current level.
Sustainable water management
To manage the rise in demand for water and to increase water productivity, incentives for using water more efficiently and avoiding water loss will be necessary. Water pricing is increasingly seen as a necessary tool. The relevant issue in this respect is describing the intricacies of potential water pricing – how does one price one of our most elusive resources? The human right to water stipulates that states have an obligation to ensure that their citizens have access to water for their basic needs. This does not necessarily mean that water for direct human use, such as for drinking or cleaning, shall be free of charge. Nor does it mean that water use for other purposes, for example for producing food, electricity or industrial goods, shall be free. When discussing a potential price on water, it is important to keep in mind that the water resource and the use of it have some characteristics that make it different from many other types of traded resources and goods.
Besides water pricing, we have to reconsider current ways of water management, waste water treatment and most important the technologies of water production and conservation. In the field of water supply, numerous solutions have already been developed and tested with various degrees of success and failure.
Let us first look at the distribution of water on the planet. 1.4 billion km3 (97.3%) is stored in the oceans and is saline. The other 2.7% is divided into groundwater, ice, surface water (lakes and rivers) and atmospheric water. All water on our planet is part of the hydrological water cycle. If we start the cycle at the oceans, from the evaporated water 90% returns to the sea and the remaining 10% to the continents as rain, hail, and snow and 13.000 km³ or 0.0001% stays in the atmosphere.
Existing and future sources of water supply
Where rainfall is scarce or irregular, the most common sources are water from rivers and pumping water from shallow or deep wells. This only works locally and cannot be repeated as often as necessary without lowering the ground water level beyond access. Looking at the gigantic volume of saline water, another popular solution is obviously the extraction of fresh water from saltwater. Situated on the coastline, large reverse osmosis plants have already been built and more will be needed. These and all other ways of producing water have one drawback in common: The water has to be distributed to be of use where it is needed. Transportation via pipelines, tankers or on the road results in high costs and often causes insuperable problems.
Water in the atmosphere
Another alternative is atmospheric water. In the form of humidity, water is present everywhere. The atmosphere contains a wealth of water and even solves the problem of delivery. The worlds natural cycle of water is a unified whole, no water can disappear. By means of evaporation, extracted water will always return into the atmosphere and the process will leave no measurable effect on air quality, oxygen content or humidity. With cooling surface and quantity of air being the key-factors for the efficient extraction of water from humidity, condenser technologies invented in the past did not offer satisfying results. The demand for efficient condenser system with better performance was obvious and gave the impetus to the development of several innovative solutions.
Water generating devices make use of two principles. The most common is that of the air conditioner. The other one is based on a chemical extraction method using a cocktail of salts. These systems still use quite a lot of electrical energy.
New and sustainable systems
Latest developments make use of a windmill to compress air through a heat exchanger, resulting in condensation which is collected in a tank. Production capacities are presently in the order of 10.000 liters per day.
Another innovation is the so-called water pyramid. It is a big white tent with a surface area of about 650 m2 to be used preferable in the tropics near the coast. Salt water, which is pumped inside, evaporates when the sun shines on the tent. The fresh water drips along the inside and is captured. On yearly basis approximately 600 m3 of fresh drinking water is produced: 300 m3 distillate and 300 m3 as a result of rainwater harvesting. Energy consumption is minimal.
About the Author
Reinout is an expert in groundwater assessment through groundwater investigations and modelling, land and groundwater remediation, redevelopment of contaminated land sites, contaminant transport modelling, development of sustainable water technologies, water purification and wastewater treatment, environmental management and technical due diligence.