October 10, 2011
Due to a growing population, frequent droughts, and the effects of climate change, it is becoming more and more challenging for California to provide enough water to meet the demands of its citizens. Even with increased conservation and reuse, traditional water sources might not be sustainable in the future. Currently, California is experimenting with desalination, a process that removes salt and other minerals from seawater, as a possible solution to the water crisis. However, current desalination technology is extremely energy intensive, contributes to global warming by emitting greenhouse gases, and poses a severe threat to marine environments. Despite California’s water issues, the combined environmental effects of desalination are too severe for the process to be considered a viable alternative water source until desalination plants can operate in a way that minimizes their impact on the environment.
According to Peter Hanlon in the article “Desalination Nation” from The Huffington Post, desalination uses eight times more energy than groundwater pumping. Hanlon describes how this process creates that he calls an “energy-water nexus”: “In short, generating electricity requires a lot of water as does treating and moving water. Desalination does not help to ease the burden of these interconnected demands, in fact it makes the situation worse.” Electric grids require a lot of water for cooling, and the amount of water produced by desalination may not be enough to compensate for the water and energy used to create it.
An additional problem caused by increased energy use is increased air pollution, which can contribute to the global climate change. Planned desalination plants will be located alongside existing power plants, potentially propelling greenhouse gas emissions (Food & Water Watch). Considering the current climate crisis, a process that uses so much energy and increases pollution may not be sustainable in the long term.
The greatest threat to the environment from desalination plants is their potential impact on marine life. According to the report Evaluating Environment Impacts of Desalination in California by Holly Alpert, Catherine Borrowman, and Dr. Brent Haddad, during the desalination process, seawater is withdrawn directly from the ocean, trapping fish and macroinvertebrates against a screen; smaller organisms that get through the screen, like plankton, invertebrates, and eggs and larvae of fishes, are killed once in the facilities. The effect of this process can be illustrated by a study of a San Onofre power generation facility that uses a similar open intake method: It was found that 4.4 million fish, of 61 different species, were trapped by the open-water intake screens in 2004, which caused a 60% decrease in fish populations within one kilometer of the facility (Alpert, Borrowman, and Haddad). Not only can the size of the population be affected, biodiversity may also be reduced by desalination causing fundamental changes in the ecological processes of the given ecosystem.
Unfortunately, the open ocean intake technology of desalination plants is not the only part of the process that can significantly impact healthy fish populations near the facilities. The disposal of wastes poses an additional threat to marine environments. After desalination, a heavily concentrated brine solution is left over. Currently, all desalination facilities in the world discharge this brine solution, containing double the salt of natural seawater as well as various chemicals, directly into the ocean (Alpert, Borrowman, and Haddad). The balance between marine life and their environment is delicate. Some organisms may be able to withstand an increase in salt, but most would not survive.
Ideally, desalination would be eliminated as a possible alternative water source, and efforts would instead be focused on increasing conservation, sustainability and recycling. However, California has already implemented legislation to allow for the construction of various plants along the coast. Therefore, the important issue now is to make sure that the plants are not allowed to operate until they do an Environmental Impact Assessment and comply with the California Water Code so that desalination has the least possible impact on the environment.
About the authors: Katherine Moreno and Madi Swayne are working towards their bachelor degrees in the USC Dornsife College of Letters, Arts and Sciences.