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Solar Desalination with Brine Recovery Salt Pans Could Stop Desert Water Wars
If solar powered desalination plants had brine recovery salt pan attachments as in Point Paterson, Austrailia they would be a better option than trying to heist water from already overburdened aquifers as the SNWA has attempted for decades. The desalination plant of the future would be solar and wind powered and use the heat of the desert sun to evaporate the salt from the brine in salt pans creating zero waste. If our society can justify spending billions on unmanned CIA drones to bomb funeral processions in Afghanistan just to kill one Taliban we certainly can invest in our future here by replenishing our overtaxed aquifers through solar powered desalination.
The Southern Nevada Water Authority's pipeline from the aquifers up north has been temporarily voted down by Utah's Governor Herbert due to overwhelming public pressure form Native Americans, ranchers and environmentalists who are concerned about the risk of groundwater depletion and extinction of endemic spring dependent species. These aquifers in northern Nevada are like many others throughout the U.S., overused and dropping groundwater levels consistantly. There may be some advantages for southern Nevada to replenish their own aquifers that caused the extinction of the Las Vegas dace several decades ago. That extinction resulting from aquifer overdraft could be excused then as ignorance though today we all know better and the pattern of aquifer depletion must be reversed by aquifer replenishment.
"Water May Soon Become A Federal Issue
If the States can't come to sensible water agreements soon, the Federal Government may get involved. It only makes sense that if inland States pay for desalination facilities off the coast, they should get more water from the rivers that lead to the coast. And coastal communities should support this because they too will get more water.
But how much more water? 1%? 5%? 20%? 50%? Negotiations for how much more water coastal communities get than upriver communities could lead to standoffs that could last for years, if not decades. If the States can't agree to providing more water for everybody, the Federal Government may step in to set guidelines.
But then again, there may be other reasons the Federal Government may get involved.
Developing a new technology is expensive. Developing renewable energy powered offshore desalination is no exception. Coastal military bases, such as Camp Pendleton, are considering desalination. Herein lies an opportunity for the use of Defense monies to develop renewable energy powered offshore desalination facilities. Also; Federal subsidies for desalination would be a sensible use of taxpayer monies.
And if that doesn't work, Nevada still can sue to get the Federal Government to pick up at least part of the bill. Nuclear Tests polluted a vast amount of underground water under the Nevada Test Site. Nevadans didn't ask to be the sacrificial nuclear test site area. Which means that the Federal Government owes Nevada for the water they polluted. Either way, Southern Nevadans could save 15 to 20 billion dollars on the watergrab pipeline and get significant Federal financial help designing/developing/building desalination facilities off the coast. Moreover, SNWA would only have to pay for desalination facilities as needed. Which means far less money up front from people in Nevada who won't really benefit from these water projects.
The people who already live in Las Vegas already have enough water. This water is for growth. The people of Las Vegas are being told they have to foot the bill for water someone else. At the present population, that amounts to almost $10,000 for every man, woman, and child in the Las Vegas Valley. When the watergrab pipeline bills start to come in, they aren't going to be happy. But if smaller desalination projects can be built, as needed, new residents can pay the bills for their own water. We shouldn't have to ask the Federal Government to force SNWA to be more fair. But apparently, it has come down to that."
The main problem with desalination is the discharge of concentrated salty water or brine being released into the ocean from desalination. The Point Paterson desalination plant in Austrailia has overcome this previously thought of as unavoidable pollution by using solar thermal salt pans.
"Port Augusta is a particularly suitable location for producing water via desalination, given its increasingly arid climate and remoteness from fresh water sources. Using solar energy to drive the desalination process is efficient for a number of reasons.
Firstly, South Australia is an importer of electricity and suffers occasional supply shortages in summer when the interconnectors to the national grid reach their limits. Secondly, producing water locally saves the energy currently used to pump water several hundred kilometres from the east of South Australia, where the increasingly scarce water is located.
South Australia also has excellent solar insolation, and the location chosen is close to existing power lines (for the Northern and Playford brown coal-fired power stations nearby), water pipelines and salt pans for solar brine harvesting.
This minimises a lot of the infrastructure costs and also enables a drawback of desalination plants (the environmental impact of discharging briny water back into the sea) into a potential positive, as it can be used to feed a salt production process instead.
The Acquasol plant will be producing water using a desalination process known as "multi effects", driven by 1.75-kilometer square concentrating parabolic trough mirror field. The desalination plant, solar thermal storage (apparently using molten salt, but this isn't clear) and other operating equipment will be sited in a small area adjacent to the solar field.
Multi-effects evaporates salt water using a vacuum and recondenses the vapor into drinking water. Both require energy, usually between 2.7-4.5 kilowatthours per kilolitre (though improvements to the technology are expected to lower this figure - hopefully to around .7 kilowatthours per kilolitre). At present, pumping Murray River water to the Upper Spencer Gulf consumes up to five kilowatthours per kilolitre. Multi-effects deslination can also use heat as an energy input, skipping the initial conversion into electricity and increasing efficiency.
The company expects that by having reverse osmosis desalination and multi-effects desalination operate side-by-side in future, powered by solar energy and incorporating thermal energy storage and a backup gas turbine backup, further operational efficiencies can be reaped that lower costs.
The water produced could also be in demand from large water users inland, like BHP's Olympic Dam mine, which currently draws around 30 megalitres of water per day from the Great Artesian Basin, and will need another 120 megalitres per day to service the expansion of the mine. BHP are currently proposing to build another desalination plant at Port Bonython near Whyalla, though this is being resisted for a number of reasons, one being a vulnerable local population of giant cuttlefish.
Another Australian experiment with desalination using solar thermal power is being performed by RMIT at Pyramid Hill in Victoria - this seems to be completely independent of the Acquasol project.
The Trouble With Water
Australia's troubles with water are well known by now, thanks to our recent bout of intense drought and the impact this has had on agricultural production and subsequently on a number of global commodity prices - rice being the most recent example.
The United States has also started to experience issues with water supplies in both the south east and south western states.
Access to fresh, clean water has increasingly become an issue worldwide in recent years, as a number of factors come into play affecting both supply and demand:
* Population is increasing - and most rapidly in drier regions
* People have become wealthier and accustomed to using more water
* Polluted water has become more common, as large swathes of the developing world industrialise
* Ever increasing demand for power (and newer forms of energy like biofuels or coal to liquids plants)
* Groundwater aquifers have been depleted by irrigation for agriculture
* The water industry is mostly made up of public utilities that have often been starved of new investment funds
* Climate change has impacted rain patterns, reducing rainfall levels and increasing the frequency and intensity of droughts
* Melting glaciers have reduced water flows
* Water has been cheap, so there is little incentive to conserve it"
Other reasons to support solar thermal desalination plants in desert regions and the Gulf of Mexico is that rising sea level will result in saline intrusions. Freshwater cypress swamps in the Gulf of Mexico are suffering from salt water intrusion and are the only natural barrier preventing the sea from entering southern Louisiana. Friendly freshwater alligators would be replaced by the more aggressive saltwater crocodiles and the cypress trees that buffer against storm surge would be killed by salt water.
Even if everyone magically stopped driving tomorrow the effects of global warming and sea level rise will remain. Moving large amounts of desalinated sea water into the interior regions to store in aquifers may be expensive, but then again so are yearly repeated floods and droughts.
"Sea-level Rise and Coastal Inundation
Global sea levels are rising due to melting continental ice sheets, melting glaciers, and warming-induced expansion of the oceans. In some parts of the South such as the Louisiana Gulf Coast, sea level rise is compounded by subsidence, the gradual “sinking” of land surface to geological processes, removal of oil, gas, groundwater or other pressurizing substances from the ground, and the lack of offsetting sediment deposition. As sea levels rise, saltwater intrudes and increases the salinity of estuaries, coastal wetlands, and tidal rivers. As a result, salt-sensitive plants and trees die and related ecosystems are forced to migrate further inland to survive, unless prevented by barriers such as roads, farms, and towns. In addition, at certain elevations, saltwater can intrude into freshwater aquifers.
By disrupting coastal forest ecosystems such as cypress swamps, sea-level rise and coastal inundation can have adverse effects on forest-related ecosystem services. For example, coastal forests and wetlands act as natural barriers to storm surges. Thus, the loss of these ecosystems increases the vulnerability of inland communities to flooding caused by tropical storms and hurricanes. Likewise, the loss of coastal forests can increase the loss of sediment to the sea. In addition, it can decrease the recreational and hunting benefits people derive from these ecosystems."
Hoyle, Zoe (2008). That Carbon Dance: Compass 10. Online at http://www.srs.fs.usda.gov/compass/issue10/issue10.pdf
The job of the federal government is to protect the people and the environments we all share. Having depleted aquifers going dry in Nevada and intruding salt water along the Gulf's coastal swamps isn't in the best interest of the people or the ecosystem. We have evidence that desalination can be performed without salty brine being dumped into the ocean so we can demand this become a priority above the military-industrial complex being funded by taxpayer dollars.
Are we to believe that it is really more beneficial to spend money on unmanned drones that only serve to anger people in other nations when they attack funeral processions and kill innocent civilians alongside the occasional Taliban or Al Queda terrorist?
Clearly logic says no to overseas military interventions and mechanized drones conducting poorly planned hits on potential terrorist targets and then killing civilians in the process. If we want the fire of terrorism to go out we need to quit feeding more fuel into the fire!!
We the people in the U.S. demand and end to the military-industrial complex and desire a more sustainalble water transport infrastructure here in the U.S. that can address rising sea level, aquifer depletion and other issues with solar powered zero waste desalination with brine recovery salt pans.