Carlsbad desalination plant

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Carlsbad desalination plant
File:Carlsbad desalination plant3.jpg
The site of the Carlsbad desalination plant is between the lagoon and the Encina Power Station. This view is looking from north to south, prior to construction of the desalination plant
Location within San Diego County
Desalination plant
Location Encina Power Station, Carlsbad, California
Coordinates Lua error in package.lua at line 80: module 'strict' not found.
Estimated output 50 million US gallons (190,000 m3) per day
Cost US$1,000,000,000[1]
Technology Reverse osmosis
Percent of water supply Estimated 7% of San Diego County
Website Official website (see Project website note under External links)

Carlsbad desalination plant (officially known as the Claude "Bud" Lewis Carlsbad Desalination Plant) is a desalination plant that opened on December 14, 2015 in Carlsbad, California, adjacent to the north end of the Encina Power Station.[2][3] The San Diego County Water Authority (SDCWA), the recipient of the fresh water produced by the plant, calls it "the nation’s largest, most technologically advanced and energy-efficient seawater desalination plant." The entire desalination project cost about $1 billion for the plant, pipelines, and upgrades to existing SDCWA facilities to use the water.

History

The idea of a desalination plant in San Diego County, California began in 1993 after five years of drought.[1] Membrane technology used in the plant was pioneered by General Atomics in La Jolla.[4] Environmentalists opposed the construction due to various concerns, most notably energy consumption, brine discharge[1] and that the ocean water intake could kill fish.[5] Five lawsuits were brought against the plant, including by Surfrider Foundation, San Diego Coastkeeper, and the Coastal Environmental Rights Foundation, but none were successful.[4][6]

Construction

The plant construction started in December 2012, and was originally scheduled to be completed in 2016.[6][7] However, due to the continuing drought in California, plant completion was advanced to late 2015.[8] The plant was estimated to be completed in September.[9] After completion, it will undergo six months of testing before being put online.[9]

The fresh water output from the plant will be sent by a 10-mile (16 km) long, 4.5-foot (1.4 m) diameter pipeline, utilizing six pumps, to connect to the SDCWA distribution system in San Marcos.[10] Pipeline construction began in 2013,[11] and was completed June 28, 2015.[12]

Poseidon Water built the plant.[13] The main engineering companies on this project were GHD Group and U.S.-based Butier Engineering Inc.[14][15][16] IDE Americas Inc., a subsidiary of Israel-based IDE Technologies, designed the plant. IDE Technologies is jointly owned by Delek Group and Israel Chemicals.[17][18] Simon Wong Engineering was subcontracted to provide the design and structural engineering services.[19] J.F. Shea Company and Kiewit Corporation constructed the plant.[20]

The plant took nearly 14 years to build.[4] The total project cost was expected to reach near $1 billion; initial cost estimates were a quarter-billion in 2004, to six hundred ninety million in 2010.[21] The cost of construction was funded by bond sales.[6] In late-2012, Fitch Ratings gave the bonds the lowest investment grade rating.[22] Upon completion, it became the largest desalination plant in the Western Hemisphere.[6]

How it works

Up to 100,000,000 US gallons (380,000 m3) per day of cooling water from the Encina Power Plant is taken into the desalination plant.[23] The water intake is filtered through gravel, sand, and other media to greatly reduce particulates before going through reverse osmosis filtration.[13] Half of the saltwater taken into the plant is converted into pure potable water and the rest is discharged as concentrated brine.[24]

The outflow of the plant is put into the discharge from the Encina Power Plant for dilution, for a final salt concentration about 20% higher than seawater. Most desalination plants discharge water with about 50% extra salt, which can lead to dead spots in the ocean, because the super-saline brine doesn't mix well with seawater.[13] The NRG Encina Power Station is expected to go offline in 2017, and Poseidon Water will then take over dredging responsibility for the Agua Hedionda Lagoon, taking over from NRG;[25] without dredging at the mouth of the lagoon, it would revert to being a pre-1952 mudflat.[26]

To offset environmental impacts, 66 acres of wetlands were built in San Diego Bay.[6] Solar panels will be installed on the roof of the plant, and carbon emission offsets will be purchased.[27]

San Diego Coastkeeper is suing the SDCWA over environmental concerns. On July 29, 2015 they argued in a hearing before Superior Court Judge Gregory Pollack that the Authority's long-term water plan (and specifically the Carlsbad desalination plant) violates the California Environmental Quality Act, specifically with respect to energy needs and the greenhouse gasses associated with those. Coastkeeper is not opposed to desalination, but wants proper mitigation. The Authority says that these have been accounted for, and a mitigation plan has been put into place.[28]

Water quantity and cost

The plant is expected to produce 50 million US gallons (190,000 m3) of water per day[29] (0.069 cubic kilometres per annum) with energy use of ~3.6[30] kWh for 1 m3 fresh water, or ~38 MW of average continuous power.[6][31] Another estimate has the plant requiring 40 MW to operate, and a cost of $49 million to $59 million a year.[1] It will provide about 7% of the potable water needs for the San Diego region.[4]

The San Diego County Water Authority signed a contract with the plant operator to purchase a minimum 48,000 acre-foot per year of drinking water, but it can also demand up to a maximum of 56,000 acre-foot per year.[32][33] (Since one acre-foot is about equal to 1,233 cubic meters, the output would be a minimum of 59,184,000 cubic meters/year to a maximum of 69,048,000 cubic meters/year.) One acre-foot is normally enough water to supply two households of four for one year.[34][35]

The cost of water from the plant will be $100 to $200 more per acre-foot than recycled water, and $1,000 to $1,100 more per acre-foot than reservoir water, but $100 to $200 per acre-foot less than importing water from outside the county.[36] As of April 2015, San Diego County imports 90% of its water.[10] A group of environmentalist groups, Desal Response Group, claims that the plant will cost San Diego County $108 million a year.[13]

References

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  9. 9.0 9.1 http://www.sandiegouniontribune.com/news/2015/apr/11/carlsbad-desalination-project-nears-completion/
  10. 10.0 10.1 Lua error in package.lua at line 80: module 'strict' not found.
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  12. http://www.kpbs.org/news/2015/jun/29/carlsbad-desalination-plants-pipeline-now-complete/
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  23. http://carlsbaddesal.com/desalination-plant
  24. http://carlsbaddesal.com/how-it-works
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  28. http://touch.latimes.com/#section/604/article/p2p-84112921/
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  31. http://pacinst.org/reports/desalination_2013/energy/energy_full_report.pdf[dead link]
  32. http://carlsbaddesal.com/project-agreements
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  34. http://www.sdcwa.org/sites/default/files/desal-carlsbad-fs-single_1.pdf
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External links

Project website note. Some of the webpages are formatted incorrectly so that in some browsers no numbers are displayed. For example, "The WPA commits the Authority to purchase a minimum ,AF/year of product water and provides the option to demand a maximum ,AF/year" could be displayed, although the actual text in the file is "The WPA commits the Authority to purchase a minimum 48,000 AF/year of product water and provides the option to demand a maximum 56,000 AF/year." If you experience this problem, you have three options: (1) try another browser, (2) copy and paste the displayed text into a document and the text should show correctly, or (3) view the page source in HTML.