An Unconventional Desalination Technology Could Solve California's Water Shortage
This year, farmers in California's Central...
Thu, Mar 13, 2014, 0:12AM EDT - US Markets open in 9 hrs and 18 mins
An Unconventional Desalination Technology Could Solve California's Water Shortage
By Dina Spector
12 hours ago
WaterFX
A
parabolic trough collects energy from the sun. The heat is used to
evaporate clean water from the salty agricultural drainage water of
irrigated crops.
This year, farmers in
California's Central Valley likely won't receive any water through the
federal irrigation program, a network of reservoirs, rivers, and canals
that is normally replenished yearly by ice melt from the Sierra
mountains.
Crippling water shortages have made desalination technology more attractive, including a startup, WaterFX, that uses the sun to produce heat. The heat separates salt and water through evaporation.
WaterFX has fewer environmental
repercussions than traditional methods of desalination that rely on
fossil fuels to generate electricity.
The technology could not have come at a better time.
No end in sight
During a drought-free year, the federally run Central Valley Project provides enough water to irrigate 3 million acres of agricultural land. Last year, farmers only received 20% of their allotment.
The lack of water is not just worrying for growers. It affects all people who eat food. One third of the nation's produce is grown in the Central Valley — composed of Sacramento Valley in the north and San Joaquin Valley in the south — and the deep water cuts mean that more than half a million acres of crop land will be left unplanted.Some scientists predict California's drought could last as long as a century . Going forward, the state is going to need a substantial water supply that doesn't rely on the aqueduct system, says Aaron Mandell, WaterFX chairman and founder.
However, in order to counter
California's drought, the push must be toward renewable desalination
plants rather than fossil-fuel dependent facilities that further
contribute to climate change.
Making freshwater from sunshineIn WaterFX's system, a solar trough, which looks like a jumbo-sized curved mirror, collects energy from the sun's rays and transfers that heat to a pipe filled with mineral oil. The mineral oil feeds the heat into a system that evaporates the salty water being treated. Steam is produced, which condenses into pure liquid water. The remaining salt solidifies and can be removed, says Mandell. That salts can be used in other industries as building materials, metals, or fertilizers.
In order to operate continuously, the solar trough is very large so that it collects extra heat during the day. The energy is stored and used to run the system at night when the sun isn't shining.
By using sun as the fuel source,
WaterFX uses roughly one-fifth of the electricity consumed by
traditional desalination plants, according to Mandell. Less electricity
means lower operating costs. With conventional desalination, electricity
makes up 50-60% of the water costs, says Mandell. A typical
desalination plant in San Diego operates at about $900 per acre-foot,
while it costs around $450 to produce an acre-foot of water with
WaterFX. (An acre-foot is 325,000 gallons, or the amount of water it
takes to cover an acre at a depth of one foot).
WaterFX
WaterFX chairman and founder, Aaron Mandell.
"Solar desalination is still a very immature technology so there's a
quite a bit of room to drive that cost down even further," said Mandell.
Many desalination facilities, including the $1 billion Carlsbad plant
set to open in 2016, use a process known as reverse osmosis that forces
seawater through billions of tiny holes that filter out salt and other
impurities. This method can produce fresh water on a large scale, but
has economic and environmental drawbacks. It uses an immense amount of
electricity and only about half of the seawater that goes into the
system comes out as clean water. The remaining half is dumped back into
the ocean as salty brine where it can be harmful to marine plants and
animals.
By contrast, Mandell says that
WaterFX has a 93% recovery rate, meaning that for every 100 gallons of
water that goes in, 93 gallons of usable water are spit out.
WaterFX also helps solve an issue
that has long plagued irrigated land. Soils in the arid west of San
Joaquin Valley naturally contain a lot of salt as well as high
concentrations of metals, like selenium, which can be toxic to humans and wildlife.
When the soil is irrigated, the salt, selenium, and other elements
become concentrated in the drainage water that collects in a system of
drains and pumps under the crops. In the past, harmful drainage water
might have been discharged into rivers, wetlands, and aquifers
in the San Joaquin Valley. Now, that otherwise unusable water can be
diverted to WaterFX and turned into irrigation water again.
The first test
The Panoche Water District in Central Valley is home to the first
demonstration plant, a 6,500-square foot system that is capable of
producing around 10 gallons of freshwater a minute, or roughly 14,000 of
freshwater each day.When the demonstration plant is operating in commercial mode, running 24 hours a day, it can put out 25 to 30 gallons of freshwater a minute, says Mandell.
WaterFX
The pilot project, funded by the
California Department of Water Resources, will hopefully prove that the
WaterFX system is more reliable (it doesn't depend on the Sierra
snowpack) and affordable than other freshwater sources.
The water that's being treated by
the pilot plant streams in from a canal that collects salty drainage
water from around 200 farms in the area and brings it to a single
location. In the pilot phase, the clean water that's produced is blended
back in with the drainage water, but a commercial plant would send the
water back to farmers through a series of canals that are already in
place.
Additionally, small-scale systems could be used by individual farmers on site to recycle their own drainage water.
A bright future
WaterFX is not the first company to experiment with solar desalination. The Sahara Forest project in Qatar and an Australian company called Sundrop Farms
are using the technology to grow food in greenhouses. But this is the
first time a company has focused on using the sun's energy "to produce a
scalable, long-term water supply," Mandell said.
The goal is to eventually be able to treat salty groundwater in addition to drainage water.
The immediate next step for
WaterFX is to expand operations in Panoche to produce 2 million gallons
of water per day. "From there it's about laying out a pathway for
replicating this model all up and down the Central Valley," Mandell
said. "We're trying to put a plan in place so that by 2020, we may be in
a position to wean ourselves off the aqueduct system entirely."
More From Business Insider
- 75,000 Killer Bees Attack A Woman, Stung 1,000 Times
- Lake Erie Is Turning To Slime [PHOTOS]
- SCIENTIST: California's Crazy Drought Could Last More Than 100 Years
No comments:
Post a Comment