Investors and policy makers are increasingly advocating desalination technologies that use seawater to make freshwater. As reviewed in an EcoSeed Special Report, the interest in desalination technologies is growing due to the fact that there is insufficient fresh water to meet the daily drinking and sanitation needs of all those inhabiting the planet.
Desalination involves the process of removing salt from sea or brackish water to produce drinkable water. According to the International Desalination Association, there are over 13,000 desalination plants worldwide producing more than 12 billion gallons of water a day. Although this may seem like a lot, this represents only 0.2 percent of global water consumption.
A report by Lux Research indicates that to meet the demands of a growing human population, worldwide desalinated water supply must triple by 2020. This report indicates that desalination is feasible, as the global water desalination market is expected to expand at a compound annual growth rate of 9.5 percent over the next 10 years.
While desalination is garnering considerable interest, it is not price competitive with traditional water sources. The construction, operation and maintenance costs make desalination at least three times as expensive as traditional sources.
Some argue that reverse osmosis (a method of passing saltwater through a membrane filter at high pressure) may be less expensive than distillation methods commonly used. The American Membrane Technology Association estimated that existing traditional water supplies cost 90 cents to $2.50 per 1,000 gallons produced. Brackish desalination technologies range from $1.50 to $3 for the same amount of water, and seawater desalination costs from $3 to as much as $8 per 1,000 gallons.
In addition to its high cost, desalination technologies are harmful to the environment. Removing salt from seawater produces brine, which contains twice the salt of seawater; they also contain contaminants that can affect marine life when dumped back to the sea. If brine is disposed on land, it could seep through the soil and pollute water reserves underground.
The US Environmental Protection Agency found that desalination plants kill at least 3.4 billion fish and other marine life annually. This represents a $212.5 million loss to commercial fisheries. Desalination plants can also destroy up to 90 percent of plankton and fish eggs in the surrounding water.
Desalination may also be injurious to human health as reverse osmosis does remove all of the boron, which is known to cause reproductive and developmental problems in animals, as well as irritation of the human digestive tract.
Perhaps most troubling is the fact that desalination plants are dependent on fossil fuels which emit greenhouse gases and contribute to global warming. Paradoxically global warming increases droughts and water shortages, the very problem that desalination plants are trying to address. Surfrider Foundation and San Diego Coastkeeper estimated that a plant that produces 53 million gallons per day will cause nearly double the emissions of treating and reusing the same amount of water.
Innovations in desalination technology do offer some promise to minimize some of these problems. Universities and water treatment companies have began to develop future desalination plants that use renewable energy. Researchers from the Massachusetts Institute of Technology and South Korea’s Pohang University of Science and Technology are developing a small chip that can repel salts away from a reverse osmosis membrane.
Water recycling is a means of purifying water so that it can be made potable. However, as with desalination, there are problems with this approach including the amount of energy needed to power wastewater recycling.
According to the National Research Council, the redistribution of water can be more efficient and cheaper than desalination. Numerous studies support the council’s report; they indicate that management alternatives and efficiency programs can reduce water supply problems at a much lower cost, without the environmental and health dangers associated with large-scale desalination plants.
Richard Matthews is a consultant, eco-entrepreneur, green investor and author of numerous articles on sustainable positioning, eco-economics and enviro-politics. He is the owner of The Green Market Oracle, a leading sustainable business site and one of the Web’s most comprehensive resources on the business of the environment. Find The Green Market on Facebook and follow The Green Market’s twitter feed.
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