· Browse Textbook Solutions Ask Expert Tutors You can ask ! Earn ... 1 out of 1 points Why is desalinization of water an unreasonable solution? Selected Answer: b. All of the above Correct Answer: b. ... Course Hero member to access this document. Continue to access. End of preview. Want to read all 13 pages?
· Question 3 0 out of 1 points Why is desalinization of water an unreasonable solution? Selected Answer: a. Waste salts need to be disposed of Correct Answer: c.
· In May, the institute published a white paper based on the event to share the results with the world, and it isn’t particularly encouraging. The consensus was that desalination is unlikely to ever contribute significantly to California’s water supply, largely because of the costs and environmental impacts. On the other hand, it could become ...
· It is based on the Second Law of Thermodynamics, a fundamental law of physics. Desalination decreases the entropy of the water and salt (by separating them, that is, by …
Some coastal sewage treatment plants are beginning to experience challenges from climate change, such as backflow from seawater and potential discharge problems. Two experts explain how facilities in the San Francisco Bay Area are addressing these risks. Feb. 26, 2018
There was a preference for subsurface seawater intakes, meaning underground, because of the impact of open-ocean intakes, where entrainment of sea life has to be mitigated. Under the new state policy, if you have subsurface intakes, there’s no requirement to mitigate those impacts.
It is easy to assume seawater desalination is the answer to California’s long-term water woes. All you have to do is look west, and the vast Pacific Ocean simply glimmers with opportunity.
The consensus was that desalination is unlikely to ever contribute significantly to California’s water supply, largely because of the costs and environmental impacts. On the other hand, it could become the primary source of water for some coastal communities.
The state itself or NGOs could try to develop policies to create a comprehensive vision for desal and come up with criteria for truly sustainable desal. That was one idea we talked about that needs further work.
First of all, it ’s very expensive. Second, it takes a lot of energy, and it’s hard to find places where you can site desal facilities that are acceptable to the local community and people who are concerned about marine resources.
That was something else that was discussed extensively. There just are no good quantification tools to really compare choices. For instance, comparing marine impacts to CO2 (climate change) impacts. There’s no ready way to compare those in California.
It is based on the Second Law of Thermodynamics, a fundamental law of physics. Desalination decreases the entropy of the water and salt (by separating them, that is, by making them less disordered). Any process that does that must be accompanied by an entropy increase elsewhere.
Answer by Richard Muller , Professor of Physics at UC Berkeley, author of Now, The Physics of Time, on Quora: The world doesn’t have a shortage of water; it has a shortage of cheap water.
Salt water pools have their own problems, including their size, the corrosive power of salt water, and the growth of algae and other plants in the pools. This question originally appeared on Quora - the place to gain and share knowledge, empowering people to learn from others and better understand the world.
Desalinated water is cheaper than bottled water, but 275x more expensive than currently available farm water in the central valley of California. It is affordable if you need water to drink and to take showers, but not if you are using it for agriculture in a world market.
The high costs and the physics limit make it look as if desalination will never be cheap enough for agriculture. But there is a potential loophole: there are cheaper forms of energy than electricity . If you have big ponds of saltwater, you can use solar heating directly.
Freshwater scarcity is already posing major problems for more than a billion people around the world, mostly in arid developing countries. The World Health Organization predicts that by mid-century, four billion of us -- nearly two-thirds of the world’s present population -- will face severe fresh water shortages.
Desalination -- a process whereby highly pressurized ocean water is pushed through tiny membrane filters and distilled into drinking water -- is being held forth by some as one of the most promising solutions to the problem. But critics point out it doesn't come without its economic and environmental costs.
The practice of desalinating salt water is becoming more common worldwide. Ted Levin of the Natural Resources Defense Council says that more than 12,000 desalination plants already supply fresh water in 120 nations, mostly in the Middle East and the Caribbean. And analysts expect the worldwide market for desalinated water to grow significantly over the coming decades. Environmental advocates may just have to settle for pushing to "green" the practice as much as possible in lieu of eliminating it altogether.
On the environmental front, widespread desalination could take a heavy toll on ocean biodiversity. "Ocean water is filled with living creatures, and most of them are lost in the process of desalination," says Sylvia Earle, one of the world's foremost marine biologists and a National Geographic Explorer-in-Residence.
Earle also points out that the very salty residue leftover from desalination must be disposed of properly, not just dumped back into the sea. Food & Water Watch concurs, warning that coastal areas already battered by urban and agricultural run-off can ill afford to absorb tons of concentrated saltwater sludge.
Food & Water Watch advocates instead for better freshwater management practices. "Ocean desalination hides the growing water supply problem instead of focusing on water management and lowering water usage," the group reports, citing a recent study which found that California can meet its water needs for the next 30 years by implementing cost-effective urban water conservation. Desalination is "an expensive, speculative supply option that will drain resources away from more practical solutions," the group says. Of course, the recent California drought sent everyone back to their drawing boards, and the appeal of desalination has revived. A plant providing water for 110,000 customers opened in December 2015 in Carlsbad, north of San Diego, at a reported cost of $1 billion.
According to the non-profit Food & Water Watch, desalinated ocean water is the most expensive form of fresh water out there, given the infrastructure costs of collecting, distilling and distributing it. The group reports that, in the U.S., desalinated water costs at least five times as much to harvest as other sources of fresh water. Similar high costs are a big hurdle to desalination efforts in poor countries as well, where limited funds are already stretched too thin.
This process, called desalination, has been turning sea and brackish groundwater into potable water since the mid-20th century.
The technology could become increasingly important in the near future, as the rising temperatures and erratic rain patterns of climate change threaten freshwater supplies. Cities with growing populations and arid climates face the possibility of running out of water, as Cape Town almost did in early 2018. But desalination is also costly and energy intensive. Many researchers are working to improve the technology so it can reach more people — and address climate change without contributing to it.
In the 1960s, a new technology called reverse osmosis (RO) began sweeping the desalination world. RO works by pushing saltwater at a very high pressure through a series of fine polymer membranes that let water molecules through but catch larger salts and minerals. After the first RO plant was built in Kuwait, the technology spread quickly and now dominates about 70 percent of the global market, says Beatriz Mayor, a researcher at the International Institute for Applied Systems Analysis in Laxenburg, Austria.
Already, Qadir estimates 142 million cubic meters of brine are produced every day by global desalination efforts, about 50 percent more than the amount of freshwater produced daily. Most brine is currently discharged into the sea and, if not done so responsibly, could threaten marine life that comes into contact with the super salty water ...
Even with these possible improvements, desalination today remains impossibly expensive for some countries, Qadir says. It can cost billions of dollars and take several years to build a desalination plant. While there is research aimed at making the process more accessible, affordability is still a limiting factor.
Desalination technology started with the simple premise of boiling water. The first desalination plant, built in England in 1945, heated water so it evaporated as steam, leaving the salts behind, and then cooled down and condensed as freshwater.
But desalination is also costly and energy intensive. Many researchers are working to improve the technology so it can reach more people — and address climate change without contributing to it. Despite the challenges, the desalination industry is expected to grow around the world over the next several decades.
Why Desalination Doesn't Work (Yet) With water fast becoming a hot commodity, especially in drought-prone regions with burgeoning populations, an obvious solution is to take the salt out of seawater. Desalination technology has been around for thousands of years, after all. Even Aristotle worked on the problem.
But the first actual practice of desalination involved collecting the freshwater steam from boiling saltwater. Around 200 A.D., sailors began desalinating seawater with simple boilers on their ships.
Currently, between 10 and 13 billion gallons of water are desalinated worldwide per day. That's only about 0.2 percent of global water consumption, but the number is increasing.
The number of desalination plants worldwide has grown to more than 15,000, and efforts continue to make them more affordable.
"In the last ten years, seawater reverse-osmosis has matured into a viable alternative to thermal desalination," Crisp says.
Back in the 4th century B.C., Aristotle imagined using successive filters to remove the salt from seawater.
The energy required for this distillation process today makes it prohibitively expensive on a large scale. A lot of the current market for so-called "thermal desalination" has therefore been in oil-rich, water-poor countries in the Middle East.
Desalination plants around the world produce about 27 billion gallons of drinking water each day – more than the daily total used by all U.S. households. However, this drought-proof approach of converting brackish or saltwater to potable water is costly because it requires a lot of energy. It also produces about one and a half times more brine than potable water.
The new approach could also help cut brine disposal costs, which can account for up to a third of total desalination expenses, and avoid damaging environmental impacts. Current brine disposal methods can cause salinity and acidity spikes along with oxygen-deficient conditions in waterways that kill or drive off animal and plant species.
Water-salt splitting separates the brine into positively charged sodium and negatively charged chlorine ions with the use of an electrochemical cell – a device that employs electrical energy to kickstart chemical reactions.
A new device capable of turning desalination waste into commercial ly valuable chemicals could make the process cheaper and more environmentally friendly.
Taking a new approach to an old problem, Stanford researchers have created a device that could make converting seawater to freshwater profitable and environmentally benign. Their research, published in ACS Sustainable Chemistry & Engineering, outlines an efficient method for transforming water with very high concentrations of salt and chemicals, known as brine, into commercially valuable chemicals as part of the desalination process. The approach avoids the need for disposing potentially hazardous chemicals in local ecosystems.
This work was funded by the Department of Chemical Engineering at Stanford University and the Stanford Linear Accelerator Center. The authors also thank the Stanford Linear Accelerator Center for support with electrode characterization (Grant No. 5474).
Stanford researchers have developed a device that can convert waste from desalination facilities into commercial chemicals. (Image credit: Pixabay/Jarmoluk) “Desalination could be a powerful tool to mitigate water scarcity around the world, but it is limited by energetic and monetary costs for treatment and brine management,” said study senior ...