March 19, 2012
The pursuit of freshwater is quickly becoming a concern comparable to oil shortages. The average American uses more than 300 liters of water a day, but of all the water that exists on earth, we can only use easily accessible freshwater. That’s .3% of the earth’s water, and that isn’t a lot to work with. By 2030, exponential population growth and accompanying industrial and agriculture needs are predicted to outstrip water supply by 40%.
California, with a population of 37,690,000 is poised to have some of the worst water supply issues, particularly because most of the population is concentrated in the driest portions of the state. However, the state’s saving grace might be the very thing that induced much of its initial population growth, its 840 miles of coastline. Because of advancements in desalination technology, Californians can now utilize our access to ocean water to produce freshwater.
Desalination is not a new concept. Two methods to desalinize water are distillation and the more popular reverse osmosis. Reverse osmosis is a riff on the principle of osmosis, which states that water naturally moves from low to high concentrations of solutes through a membrane. Reverse osmosis utilizes external pressure to reverse the flow of osmosis, so that water moves from high to low solute concentration. External pressure comes in the form of cylindrical rotors that spin 1,200 times per minute to reduce solute concentration. The Sand City Desalination Plant, for example uses this reverse osmosis system and achieves 99% reduction of solutes. The water is then disinfected by ultraviolet light and chlorination, achieving 99.99% elimination of potentially harmful bacteria and viruses.
Due to these new technologies, the environmental concerns associated with desalination are low, especially compared to the costs of current water acquisition methods. The main way that Southern California currently attains water is through water diversion, reallocating water from lakes and rivers and diverting them into aqueducts. These often depletes lakes and rivers, negatively altering important ecosystems and potentially destroying them, as in the case of Owens Valley. The sea life that desalination plants may affect due to impingement and entrainment of animals would likely be no more seriously damaged than the organisms disrupted by extensively damming and diverting bodies of water like the Colorado River. Damming and diverting are severely detrimental to local ecosystems, harming plant and animal species diversity.
Other causes for concern for water desalinization plants are the energy usage and brine residue left after the distillation process. Environmentalists claim that brine residue can be harmful to sea life by making waters too saline for native species to survive in, but it is possible to mitigate damage. In Sand City’s desalination plant, brine solution is effectually pumped into the naturally high saline Monterey Bay. In regards to high-energy usage, desalinization plants have added energy recovery devices to increase output and decrease energy consumption by using pressure exchangers. The PX Pressure Exchanger used in Sand City recovers up to 98 percent of the energy from the stream of concentrate and uses opposing forces of fresh sea and salt-heavy waters to power a rotor that moves water around and out of the system.
These environmental concerns are not to be dismissed, but to be taken into account when considering improvements to current desalination technology. Nonetheless, the prospect of providing “drought-free” fresh water to humans outweighs the environmental costs. Desalination produces a reliable and locally available source of water, especially useful in places that experience drought regularly, just like Southern California. With looming water shortages the daily 50 million gallons produced by the potential Huntington Beach plant is a not something that Californians can afford to pass up.
Sarah Beshir and Ashley Lukashevsky are undergraduates in the USC Dana and David Dornsife College of Letters, Arts and Sciences.
February 27, 2012
A few centuries ago, water use was not a problem because it was seen as a renewable resource that can never be overexploited. However, as population growth increases exponentially, water use likewise increases, depleting water resources at an unsustainable rate. As we use groundwater and surface water at a rate faster than their replenishment rate, we must look towards other sources to obtain water. One proposed solution is desalination, a process that removes salt from saline water. There are three techniques associated with desalination: electrodialysis, freezing, and reverse osmosis. Electrodialysis uses porous members to remove positively and negatively charged salt ions; freezing, by default, removes salt from ice; and reverse osmosis is a process that pressurizes salt water so that water flows through a membrane while the remaining salt are retained (Desalination Process).
Desalinization, while is considered an alternative water supply, has its fair share of negative environmental impacts that could potentially harm large communities of marine organisms. First, the discharge from the desalination facilities carries saline water back into the ocean, which affects benthic organisms that are not accustomed to water with such high salinity. Similarly, discharged water can contain chloride, heavy metals, and cleaning chemicals that would foul ocean water and poison marine animals.
Furthermore, the power consumption required for the process of desalination consumes fossil fuels, which leads to carbon dioxide emissions. As known, carbon dioxide has detrimental effects on the environment, including warming of the earth and human health risks.
Desalination also requires an extensive amount of energy to work. If desalination were to produce half of America’s water, the United States would need to construct 100 more electric power plants (Why Desalination Doesn’t Work). And the energy cost of consuming the necessary amount of energy to produce usable water would exceed the cost to pump water from aquifers or to import the water. Therefore, desalination is not a very cost-effective method and should be used with caution.
In one example, Huntington Beach has proposed desalination in order to provide water to their community. This desalination facility, if successful, would provide 50 million gallons of drinking water per day (Proposed Desalination Plant Wins Permit). However, opponents criticize desalination as energy-intensive and expensive. Furthermore, the construction of the facility near a popular beach would inevitably harm aquatic organisms, which could reduce tourism and recreation.
While it’s necessary to address the current water crisis and some may claim that the damage to marine organisms is insignificant in comparison to the benefits to society, desalination conflicts with the energy-crisis, which would mean that through desalination, we are essentially trading one problem in for another. Especially since most desalination plants require the use of fossil fuels, desalination would exacerbate the energy-crisis, depleting energy resources from other uses.
Despite their criticism, opponents do acknowledge the current water problem, so they propose alternative solutions, including improving irrigation systems and requiring new homes to be water-efficient. These solutions are more focused on conservation of water, which can help communities be more conscientious of their water usage and supply more water to each individual.
Kaylee Yang and Marc Chua are undergraduates in the USC Dornsife College of Letters, Arts and Sciences.
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.
Our entire world runs off of water. Everything from the food we eat, to the paper we draw on, we are dependent on a consistent source of freshwater. That’s why, with our population doubling every fifty years, fresh water is starting to become an area of concern. This new issue has scientists and governments searching for alternatives to help save the water supply before its too late. Some alternatives have been extremely successful such as the water recycling taking place in Fountain Valley, California, while others such as desalination have proven both costly and harmful to the environment.
Desalination is the process of removing salts and other minerals from water that is otherwise harmful to the human body and biosphere. While desalination may seem like a major hope the future, the current processes we use to remove these salts have been extremely energy abusive and economically unfeasible. In order to convert seawater to drinking water, desalination requires having a major source of energy. Due to the massive amounts of energy used, the price of water increases over twenty five percent to that of water taken from aqueducts. The average acre of freshwater costs approximately $700, while the same area of desalinated water can cost upwards of $950.
Another major cost associated with the conversion of seawater to fresh water is the need to pump water from the sea to areas of use, sometimes lifted over 2000ft. In many cases, it is much more efficient to reroute water from an aqueduct than it is to pay the bills associated with lifting the water. While the economics behind desalination are extremely high, the environmental impact is also costly.
Desalination removes vital nutrients from our local waters, not simply at the microbial level, but as well as larvae and other organisms. There isn’t a way around this, simply because the intake of any seawater to be used in desalination will contain these important nutrients. Once the process of desalination has occurred, the remaining salt must be disposed of and in most cases that is back into the ocean where it increases salinity of our costal ecosystem that is already plagued by both urban and agricultural runoff. While the salty byproduct, can be diluted in other flows of water into the oceans such as runoff or output from treated sewage water, the negative affect from the intake outweigh the benefits of an increased freshwater supply.
Food & Water Watch advocates for better fresh water management practices. “Ocean desalination hides the growing water supply problem instead of focusing on water management and lowering water usage.” A key issue to focus on is the overall water usage of the population in southern California. With the growing need for freshwater, desalination may not quench southern California’s increasing thirst for freshwater. The environmental implications of desalination surpass the fiscal benefits water companies stand to gain and undoubtedly allow for further degradation of our costal ecosystems while not addressing overall water conservation.
About the authors: Lucas Biging and Nick Leonard are working towards their bachelor degrees in the USC Dornsife College of Letters, Arts and Sciences.
As global population continues to rise, the amount of freshwater available for human consumption becomes an increasing issue. Though sources are rapidly depleting, the United States in general has yet to understand the importance of conserving water.
For coastal states such as California, an alternative means to obtaining freshwater is right at their disposal: the ocean.
The spotlight on desalination has been glowing brighter in recent years, as researchers debate on whether or not it is an adequate provider of water for the public. But while desalination provides a new source of freshwater, the environmental and monetary costs outweigh the potential benefits considering the lack of focus on conservation in California.
As far as the environment goes, negative effects of desalination are far too great at this point; the debris left over from distilling the water is put back into the ocean, increasing salinity and killing off biodiversity that is not adapted to such high levels of salt. According to David Rosenfeld, “desalination plants have the potential to entrap sea lions, millions of fish and other marine life,” their environmental impacts also including “the heavy concentrates of salt and the remains of other chemicals that could be dumped into the ocean,” as he writes in his article, Conservationists Push Back Against Desalination in California. When species all around the world are already rapidly declining due to anthropogenic reasons, consciously decreasing ocean biodiversity is not the answer to finding more sources of freshwater.
In addition, desalination is an extremely energy intensive process. Rosenfeld furthers his argument to say that desalination has a massive carbon footprint—around 40 percent of the operating cost is the cost of electricity used to power to plant.
Even while the issue of wasted energy can be mitigated with improved technology, the biodiversity lost cannot be replaced, and the costs put into the additional technology renders the whole business impractical.
While desalination seems like one of the only options for increasing our freshwater resources, in addition to the environmental degradation, it is currently not economical. A proposed plant in Carlsbad is estimated to cost $700 million dollars and will satisfy only 8% of San Diego’s water needs. For this 8% of the water supply it will use as much electricity as 45,000 homes, which is an additional recurrent operating cost on top of the $700 million. The amount of energy required for desalination is extremely high and will be very costly. The cost of water from the desalination plant will be tied to the cost of energy and as the price of energy rises, so will the price of water. “The Public Utilities Commission has approved a plan to allow publicly traded California American Water to potentially quadruple water bills on 40,000 ratepayers in order to pay for the proposed plant,” writes Rosenfeld. Consumers are unaware that the cost of desalination plants will be passed on to them, which is why they are cost-effective for the owners of the plant.
In terms of the allocation of state money, while our education system struggles on budget cuts, Proposition 50 (passed in 2002) provide $50 million to support desalination projects. This year, the Metropolitan Water District of Southern California reduced its conservation to $10 million while allocating $350 million for the Carlsbad desalination plant and promising $250 per acre-foot of fresh water produced to future desalination plants. Rather than spending tons of money on desalination plants that are harmful to the environment, we should first focus on maximizing conservation. While at some point, desalination might be necessary for human survival, we should increase our conservation first: “In parts of Southern California, up to 70 percent of all household water is used outdoors, mostly to water lawns, and an estimated 1.3 billion gallons of wastewater drains into the ocean each year” (Rosenfeld). Southern California is a desert and people living here need to accept that they cannot have a green lawn. If you want a green lawn, move to Northern California or Oregon. Otherwise plant some native plants that don’t need as much water and stop exploiting our water resources just to have a pretty front yard. In terms of in house conservation, low-flow toilets and showerheads, efficient washing machines and dishwashers could all be made extremely affordable if state subsidies were reallocated from desalination plants to conservation technologies.
Desalination plants cause too much environmental degradation and are too expensive to be implanted when there so much there is so much left to be done as far as conservation. We can reevaluate the need for desalination plants when excessive water use has been reduced significantly.
About the authors: Leslie Chang and Lauren Taymor are working towards their bachelor degrees in the USC Dornsife College of Letters, Arts and Sciences.