The Water Crisis: Can Seawater Desalination Solve It?

Today, 1 out of 3 people do not have access to clean drinking water. Most of the water on Earth is undrinkable seawater. A small amount is underground freshwater or in glacier ice that we cannot access. The remainder is in the rivers and lakes that we have contaminated with environmental pollution. Despite the many billions of gallons of water that cover our planet, less than 1% of it is available as drinkable water. We are living in a water crisis that some people in developed countries may not be aware of, but soon it will become more obvious. It is projected that half our global population will be living in water scarce areas by 2050. Right now, the struggle against water scarcity is beginning to impact communities even in the United States. In a 2011 article, The Future of Desalination: Energy, Technology, and the Environment, Menachem Elimelech et al makes it clear that "water scarcity is one of the most global challenges of our time." Every human on our planet needs clean, drinkable water to survive. This is a struggle that affects people from every country and way of life.

Since the struggle began, researchers have been seeking a potential solution to water scarcity in coastal areas where the problem requires a complex solution. One such solution being used today is seawater desalination. Essentially, desalination is when you remove salt from water. This happens naturally when the sun heats the water at the surface of the ocean and evaporates off. Later, it falls again as rain. If you want to remove salt from water outside of the natural process, it is very complicated because once salt combines with water it becomes a completely new chemical solution. This is where the two main types of desalination are involved.

The first type is thermal desalination, the oldest form of desalination. The seawater is boiled and steam is captured which is then used as drinkable water. The second type of desalination is reverse osmosis or seawater reverse osmosis (SWRO), developed at UCLA in the 1950s. This more modern process uses high pressure to force seawater through a membrane which separates the salt from water. This is a simplified explanation for a very complex process. That is one reason why it is only recently that technology has developed far enough to make SWRO a viable method of producing freshwater. The question remains, however, whether SWRO is the most environmental and economical option while water shortages continue to increase.

To begin with, even though Elimelech et al claims that "the amount of power needed to drive desalination in SWRO plants has declined dramatically in the past 40 years," the energy cost of seawater desalination can still be 25 times greater than that of other methods for producing freshwater. Advances in technology have allowed seawater desalination plants to become a costly improbability rather than an impossibility. It also must be taken into account where the energy comes from and how the source of energy for seawater desalination plants can carry an additional environmental deficit in terms of their carbon footprint.

The energy costs alone are concerning, but there are also the monetary costs to consider. In places where it is used to offset water imported from inland sources, they can potentially spend twice as much on seawater desalination. Some say that in the future the costs will be comparable. However, according to others--such as Poseidon Water, that operates the Claud-Lewis Carlsbad Desalination Plant just outside of San Diego, California--the greater cost of sea water desalination is due to developing the "infrastructure deficit" to support it whereas freshwater is being imported from systems already established and paid for. There is no way to mention the infrastructure of seawater desalination plants without also mentioning the environmental impact they have on the local marine ecosystems. In order to access enough seawater to desalinate, most plants pull directly from the ocean in shallow water. This involves seawater intake pipes that have the potential to trap or pull in smaller fish and marine life along with seawater. Elimelech et al further explains that this "can kill a large number of juvenile-stage fish, although the impact on a population level is not clear..." simply because we do not have enough long-term data to predict the environmental impact. Another concerning environmental impact involves the substantial byproduct of seawater desalination: brine. While desalination plants are not only producing clean drinkable fresh water, the byproduct of this process is hyper salty water called brine that can have up to 22.5% more salt than average seawater. For every two gallons of seawater taken in, most plants will produce at 50% efficiency so that they will produce 1 gallon of fresh water and 1 gallon of hyper saline brine. Overall, seawater desalination plants are producing more brine than fresh water. Global production of brine is at 37 billion gallons per day. When the salt heavy brine sinks to the bottom of the ocean, it has the potential to kill plants and sea life there. Posiedon Water says "the regulations in California provide sufficient environmental protection." Most claim the amount of saline produced is not enough to harm the environment. However, we do not yet know the long-term effects of brine on marine life because, according to Elimelech et al, the published data is "inadequate to establish the salinity level at which marine organisms can tolerate long-term exposure." Despite the lack of scientific data on its long-term environmental effects, seawater desalination plants across the world continue to dump their brine into the ocean.

In conclusion, many believe that the costs of seawater desalination are outweighed by the benefits such as reliable production. Others believe that the energy costs are comparable to other energy intensive demands in our everyday lives, such as powering your house. However, what even more people agree on is that seawater desalination is only one part of a greater solution to the water crisis. Seawater desalination alone will not meet the rising demands for drinkable water, as populations grow and environments change. Ultimately, other measures must be put into effect before a community relies on environmentally impactful methods such as seawater desalination. However, these methods will not increase water sources. They simply make our use of water more efficient. In the United States alone, according to the U.S. Geological Survey, the average person uses about 80-100 gallons of water per day. While water saving toilets and faucets are being used even now, those methods alone will not be enough. Most people in water rich areas take it for granted that they have enough water to drink, as well as bathe and flush their toilets. Before even water rich areas are affected, such wasteful water practices need to change. Water conservation methods and the reasons why we need to conserve water should be a part of our educational curriculum. For every drop of water we waste today, it is one less drop for our grandchildren.