Middle East Desalination

Huntington Beach Proposal

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Huntington Beach Proposal

Desalination is seen by some as a solution to the problem of a shortage of potable water. In the state of California alone the population is expected to increase by 60,000 people per year. In an effort to meet the demand for fresh water, California already has 11 seawater desalination plants in operation along the cost. An additional 21 plants are in the planning stages. Desalination technology is becoming more beneficial in the cost aspect. Over the last decade the price has gone down from $2,000 per acre foot in 1990 to $800 in 2003. (An acre foot is equivalent to 326,000 gallons or about one households use in a year). As an incentive to increase the production of desalination plants, the Metropolitan Water District in Southern California is offering subsidies of $250 per acre foot. States such as Florida, Texas, Hawaii, and New Mexico are also applying desalination technology to meet their water demand needs.

http://www.surfcity-hb.org/files/users/planning/Section%203.0%20-%20Project%20Description.pdf

In addition to using seawater for desalination, brackish ground water may also be used. Below are some statistics comparing the two.

 

	Seawater	Brackish Groundwater
Energy use	3,260-4,900 kWh per acre foot	1,300-3,250 kWh per acre foot
Plants in operation	11	40
Plants in planning	21	30-35
Salinity Concentration	5,000-20,000 ppm	< 30,000ppm

The energy and cost is lower in the desalination of brackish groundwater because of the lower saline concentration.

Legislation
There are various regulatory bodies overseeing the planning, building, and maintenance of desalination plants in the United States. Some bodies include the EPA, Coast Guard, and the Army Corps of Engineers. Specifically California desalinations are regulated under the California Coastal Act, among others. Details of this act are discussed below.

California Costal Act and Environmental Impacts
Two sections of the California Costal Act specifically address the issues of marine life and water quality and are stated as follows:

Section 30230:
“Marine resources shall be maintained, enhanced, and where feasible restored. Special protection shall be gives to areas and species of special biological or economic significance. Use of marine environment shall be carried out in a manner that will sustain the biological productivity of coastal waters and that will maintain healthy populations of all species of marine organisms adequate for long-term commercial, recreational, scientific, and educational purposes.”

Section 30231:
“The biological productivity and the quality of coastal waters, streams, wetlands, estuaries, and lakes appropriate to maintain optimum populations of marine organisms and for the protection of human health shall be maintained and , where feasible, resorted through, among other means, minimizing adverse effects of waste water discharges and entrainment, controlling runoff, prevention depletion of ground water supplies and substantial interference with surface water flow, encouraging waste water reclamation, maintaining natural vegetation buffer areas the protect riparian habitats, and minimizing alteration of natural streams.” http://www.coastal.ca.gov/energy/14a-3-2004-desalination.pdf


Intake and Discharge
In the process of reverse osmosis, the technique used most in the US, for every 2 gallons of intake water, 1 gallon of potable water is produced and 1 gallon of brine is produced. Intake, the first step in desalination, and discharge can have the potential to adversely harm marine life. The California Costal Act states that the water and marine life should at the minimum be maintained, a task which intake and discharge practices can impede on. During intake, marine life can be harmed or even killed when they are pulled into the intake pipe and are unable to escape due to the large water velocity.

Potential Solutions:
A solution to the intake problem is the potential use of a subsurface intake such as a beachwell or an open water intake. In areas where the soil types consist of clay, silt or unfractured rock, this alternative would not work. Ideally sandy soil would be needed to act as a natural filter.

The city of Long Beach, California has proposed a system that would reduce the harmful effects of intake. They plan to use a system of pipes located underneath the sand in the ocean. Sand acts as a natural filter to the water being drawn into the plant. This system can also be used for the highly concentrated brine byproduct of desalination that is discharged. http://www.lbwater.org/desalination/Under.html

Other Solutions:
1. Reducing the intake velocity- Fish and other organisms are able to escape or avoid being pulled in when the velocity is below .5 feet per second.
2. Velocity Caps-Fish have the ability to detect changes in horizontal velocity, but have a difficult time detecting changes coming vertically. Most intake systems pull water from above, making it difficult for the fish to detect. Placing a cap on the intake and leaving a gap between the intake and the cap allows for a flow that can be detected by fish.
3. Screens and fish return systems- screens placed at the landward side of the intake system allow fish to be release into an area prior to the plant. A fish return system can be implemented in this area to route the fish back to the body of water.

Discharge:
The brine discharged from a desalination plant can have a saline concentration of 70,000 ppm compared to the intake water of 35,000ppm. Organisms are adapted to the natural saline concentration and most of the time cannot handle the dramatic increase in concentration. Also, organisms at different stages of their lives have different sensitivity levels to saline.

“Chemicals used during the desalination process include chlorine, ozone, or other biocides, various coagulants, acids, antiscalants, and others”. http://www.coastal.ca.gov/energy/14a-3-2004-desalination.pdf Contaminants found in the intake water also become part of the waste stream produced through desalination.

The filters and membranes used in intake and the desalination process itself collect biomass. The accumulated dead organisms are forced to become part of the plants waste.

Solutions:
1. Location, Location, Location! - finding a proper location for discharge is crucial. Discharge should be done in areas where the population is not sensitive to changes in water quality.
2. Diffusers- allowing the discharge to be spread over a large area can result in faster diffusion into the water.

It is very important to note that the environmental impacts as well as cost and benefits vary from place to place.



http://www.coastal.ca.gov/energy/14a-3-2004-desalination.pdf

BENEFITS OF DESALINTAION
Seawater is not in short supply
Reduce withdrawal from surface and groundwater sources (top 2 http://www.coastal.ca.gov/energy/14a-3-2004-desalination.pdf
Local control of water supplies
Reliable water source in times of drought (next 2 http://resources.ca.gov/ocean/97Agenda/Chap5Desal.html)
• improved fish habitat due to reduced diversions from rivers, streams, and groundwater
• energy savings and less air pollution if the amount of water being pumped across the state is reduced
• greater protection of high-quality groundwater due to reduced pumping of aquifers (bullets from http://currents.ucsc.edu/05-06/07-11/desalination.asp)
Disadvantages http://www.unep.or.jp/ietc/publications/techpublications/techpub-8e/desalination.asp
High Cost
Not energy efficient

 

http://www.wildnatureimages.com/HB%20Surfer%20Sunset%202.htm
Huntington Beach, California
There is a current debate in Huntington Beach, California, located in Orange County, over a proposed reverse osmosis desalination plant on 11 acres of land. It would be capable of producing 50 million gallons of water a day and contain transmission lines to other cities. A vote by the city council to approve the project has been postponed to December 19th, 2005

The plant would be located adjacent to the Huntington Beach Generation Station (HBGS) which uses a once through cooling system with an offshore intake and outfall. Water would be taken from the cooling system. HBGS uses an intake structure that is located about 1,840 feet offshore. The brine discharge created would be blended with HBGS discharge and released. http://www.surfcity-hb.org/files/users/planning/Section%201.0%20-%20Executive%20Summary.pdf

There are other techniques in the process of desalination, such as multi-effect distillation, and alternatives to the intake method, such as using vertical wells. Neither of these alternatives are feasible because of the extreme heights of the vertical tubes required for muti-effect and the dependency of electrical power to generate steam. The number of vertical wells required to meet the 50 million gallons per day output is infeasible.

Reverse Osmosis membranes would have the capability to “retain and remove over 99.5 percent of the seawater salinity; over 99 percent of the metals and organics; 99.99 percent of the bacteria and other pathogens (Giardia and Cryptosporidium) and 99.9 percent of the viruses in the source water.” http://www.surfcity-hb.org/files/users/planning/Section%203.0%20-%20Project%20Description.pdf In addition, the desalinated water would be treated with chloramines to provide another level of safety.

 

http://www.surfcity-hb.org/files/users/planning/Section%203.0%20-%20Project%20Description.pdf

Controversies: http://www.surfcity-hb.org/files/users/planning/Section%201.0%20-%20Executive%20Summary.pdf
The city council has identified three major controversies as identified by the public.

1. Current harm to marine life through the once through cooling system, and the potential harm that could arise from the proposed project.
2. The potential of growth-impacts due to the project
The potential for a new seemingly unlimited supply of freshwater may draw an increased population to the coastal areas.
3. Pipelines are in existence for regional distribution of existing water, but there is a potential for the new system to be incompatible.

For more information on the Huntington Beach City Council’s decision, environmental impact statements and staff reports click http://www.surfcity-hb.org/citydepartments/planning/major/poseidon.cfm.

 

Sources are listed as they are used in above text.