Introduction
It’s a startling statistic, but only about 1% of the world’s water is fresh. In contrast, the vast majority (about 97%) of world water supplies are saline (salty water) and are unsuitable for human consumption. This saline comes not only from the ocean, but from natural lakes located over ancient seabeds, underground aquifers, and water produced by human activities.
As the world’s population grows and the global climate undergoes unpredictable adjustments, the demand for fresh water is soaring, not only for drinking, but for agriculture, livestock, industry, natural ecosystems and more. In areas where clean natural water sources are severely limited, the health of the population is affected, and economic growth is stunted.
As limited freshwater sources are being stretched beyond capacity, more countries are turning to desalination plants to supply industry, agriculture, and even to create freshwater from the ocean. Of course, as with most global challenges, the solutions are never easy or straightforward. Removing salt from water to make it drinkable is surprisingly difficult. There is no way to reduce the salts to simpler and harmless compounds since they are already the simplest of inorganic compounds, so none of the typical wastewater treatment strategies will work.
Desalination technology has been developing as the need for fresh water has outpaced its availability, groundwater sources have become depleted, and fresh surface water in reservoirs and rivers has begun to dry up. Desalination is known to be expensive and energy-intensive, but it also creates a host of new problems that need to be solved if this is to be a long-term response to the world’s thirst. Some of those problems can be addressed through relatively cheap, effective, and environmentally safe brine reservoirs and evaporation ponds.
Why Does Water Scarcity Matter to Me?
The world’s freshwater supplies are being dangerously overdrawn. The combination of population growth, changes in climate, and increasing drought are putting huge pressures on surface water reservoirs, underground aquifers and rivers. According to the USGA, the Colorado River’s flow volume has declined about 20% over the last century, most of that due to increasing temperatures. Even an increase in climate-change induced storm events like atmospheric rivers are not projected to make up for the shortfall.
This example is a critical concern because the Colorado River supplies fresh water to five states in the American Southwest, including major cities like Denver, Los Angeles, and Las Vegas, as well as some of the most productive farmland in the country. Reduction in the river’s flow coincides with ever-increasing populations and is imperative for regional farms to produce more food even as aquifers are depleted, and ongoing droughts make precipitation wholly unreliable. In fact, enormous swathes of the US actually have very little water. Both Arizona, with a growth rate of 40% per year and Nevada, which is growing at about 60% per decade, are in dire need of water - much of which comes from the Colorado river.
The problems with water scarcity extend well beyond the US borders. The World Resources Institute calculates that water withdrawals around the world have more than doubled within the last century and continue to increase. Alarmingly, one quarter of the world’s population live in countries that withdraw more than 80% of their water supply every year. That enormous pressure on available water means that not only are they extremely vulnerable to drought, but that they lack enough resources to continue to grow and develop their economies. These are not distant, underdeveloped places, either. Large cities like Rome, Cape Town, South Africa, and Chennai, the sixth largest city in India, have all experienced nearly catastrophic water shortages in the past several years. In this environment, it’s no wonder there’s a worldwide drive to extract drinkable water from the ocean. In fact, even considering their high cost, desalination plants are often the most appropriate solution to persistent water stress.
