Difference between revisions of "Desalination in California's Central Coast Region"

From CCoWS Wiki
Jump to: navigation, search
(Customer Rate Increase)
(Links)
Line 149: Line 149:
 
<references/>
 
<references/>
  
==Links==
+
==See also==
 
*[[CalAm Use of Carmel River Groundwater Basin]]
 
*[[CalAm Use of Carmel River Groundwater Basin]]
 
*[[ Los Padres Reservoir Capacity Issues]]
 
*[[ Los Padres Reservoir Capacity Issues]]
 +
*[[Carmel River]]
 
*[[ The Carmel River Watershed]]
 
*[[ The Carmel River Watershed]]
 +
*[[Carmel Valley Aquifer]]
 
* [[Monterey Peninsula Groundwater Replenishment Project]]
 
* [[Monterey Peninsula Groundwater Replenishment Project]]
 +
*[[Seaside Groundwater Basin]]
 +
*[[Salinas Valley Seawater Intrusion]]
  
 
== Disclaimer ==
 
== Disclaimer ==
  
 
This page may contain student work completed as part of assigned coursework. It may not be accurate. It does not necessary reflect the opinion or policy of [http://csumb.edu CSUMB], its staff, or students.
 
This page may contain student work completed as part of assigned coursework. It may not be accurate. It does not necessary reflect the opinion or policy of [http://csumb.edu CSUMB], its staff, or students.

Revision as of 14:54, 7 April 2014

Summary

Desalination is being considered as an alternative supply for water in Central California. In 2009, the California State Water Resources Control Board issued a Cease and Desist Order, requiring CalAm to reduce its pumping from the Carmel River by 70% by 2016 [1]. The Carmel River is the primary water source for the region, therefore, a significant water supply alternative is needed. The central coast also relies heavily on groundwater supplies. However, problems with seawater intrusion make this a not sustainable alternative. As a result, many proposals for desalination facilities have been submitted as a possible solution to the water gap.

Desalination facilities in the Central Coast

Proposed and existing desalination plats in Monterey Bay. Image: MBNMS 2006

Existing

Proposed

Unit conversions

Desalination plants are generally rated in terms of Million Gallons per Day (MGD), whereas water supply planning is often accounted in Acre Feet per Year (AFY).

1 MGD = 1,120 AFY

MGD AFY
0.5 560
1 1,120
2 2240
5 5600
10 11200

Main Issues

Energy Consumption

Comparison of the energy intensity of California water supplies. Image: Pacific Institute [7]

The proposed desalination technologies for the Central Coast are energy intensive. Producing a million gallons of desalinated seawater uses about 15,000 kWh [7], which is equivalent to the energy use of 913 California homes per day [8]. Most of the total energy use goes towards the reverse osmosis process (70%), while pre- and post-treatment and pumping account for 13% each [7]. Pumping water from the ocean to the plant is an additional 7%.

Greenhouse Gas Emissions

High energy consumption of desalination results in high carbon dioxide emissions. Most projects, such as the Monterey Peninsula Water Supply Project, will tap into the existing power grid. As the central coast transitions to renewable power sources, desalination emission estimates may decrease. Some of the theoretical emissions associated with some of the proposed desalination plants in the Central Coast are below [7]. As a reference, 1 MMT of CO2 emissions is equivilent to about one year of electricity use by 193,000 average California households [9].

Project Location Capacity (MGD) Energy Use (MWh/day) Emissions (MMT CO2e/yr)
City of Santa Cruz, Soquel Creek Water District Santa Cruz 5 75 0.007
Monterey Peninsula Water Management District Del Monte Beach, Monterey 2 30 0.0003
California American Water North Marina 10 150 0.01
Ocean View Plaza Monterey 0.25 3.8 0.003

Impacts to the Marine Environment

The main potential impacts from desalination to the marine environment are impingement and entertainment of marine organisms at the water uptake as well as potential harm from the disposal of highly concentrated salt brine back into the environment [10]. Impingement occurs when fish and other organisms are trapped against inflow screens, which often results in death. Entrainment is when organisms are drawn into the facility, which are exposed to high pressure an temperatures.

Impacts to the marine environment are of particular concern in the Central Coast because the proposed facilities will operate within the Monterey Bay National Marine Sanctuary (MBNMS). The mission of the MBNMS is to protect natural resources and to implement their mission three of the Sanctuaries regulations are related directly to preventing impacts from desalination [11]: 1. "prohibition on discharging or depositing any material within Sanctuary boundaries", 2. "discharging materials outside of the boundaries, which subsequently enter Sanctuary waters and negatively impact MBNMS resources", and 3. "prohibition on activities that cause alteration of the seabed".

Marine impacts can be avoid or minimized with careful planning and mitigation measures. Subsurface intakes can minimize impingement and entrainment compared to traditional open ocean intake methods [11]. Siting projects away from sensitive habitat or highly productive areas can also reduce the impact. To reduce impacts from brine discharge, it is recommended the brine water be diluted to a salinity of less than 5% above ambient concentration at the point of discharge [12].

Customer Rate Increase

The cost of desalination is falling, but remains an expensive alternative. Given the high construction and energy costs, customer water bills are expected to increase with desalination. For example, a typical customer should expect their water bills to increase by approximately 40% by 2018 if the proposed Monterey Peninsula Water Supply Project is approved[13]. Below is an estimate of what a typical customer will expect to pay with the implementation of the Monterey Peninsula Water Supply Project [14].

Monterey Water Supply Project monthly bill estimate
2013 2014 2015 2016 2017 2018
$75.74 $79.86 $88.42 $97.27 $97.38 $106.73

Regulatory Agencies

Federal

State

Local and Regional

References

  1. http://www.mpwmd.dst.ca.us/CDO/FinalCDOPage.htm
  2. 2.0 2.1 2.2 http://montereybay.noaa.gov/resourcepro/resmanissues/pdf/110806desal_final.pdf
  3. Sand City Water Supply Project http://www.sandcity.org/News_and_Events/Sand_City_Water_Supply_Project.aspx
  4. City of Santa Cruz Water Department Desalination Project http://www.scwd2desal.org/
  5. Ocean View Plaza Coastal Development Permit Application http://ventana.sierraclub.org/conservation/ocean_view_plaza/OVP_CSD_Staff_Report.pdf
  6. http://www.cpuc.ca.gov/Environment/info/esa/mpwsp/index.html
  7. 7.0 7.1 7.2 7.3 Key Issues for Seawater Desalination in California http://pacinst.org//wp-content/uploads/sites/21/2013/05/desal-energy-ghg-full-report.pdf
  8. http://www.energy.ca.gov/reports/400-04-009/2004-08-17_400-04-009ES.PDF
  9. http://www.arb.ca.gov/cc/factsheets/1mmtconversion.pdf
  10. http://www.pacinst.org/wp-content/uploads/sites/21/2013/02/desalination_report3.pdf
  11. 11.0 11.1 Guidelines for Desaination Plants in the Monterey Bay National Marine Sanctuary 2010 http://montereybay.noaa.gov/resourcepro/resmanissues/pdf/050610desal.pdf
  12. State Water Resources Control Board (2013) Desalination Plant Entrainment Impacts and Mitigation http://www.swrcb.ca.gov/water_issues/programs/ocean/desalination/docs/erp3_desal9062013.pdf
  13. http://www.amwater.com/caaw/customer-service/rates-information/regional-desalination-project.html
  14. Monterey Water Supply Project: California American Water updates Customer Rate Impact estimates for proposed Monterey Peninsula Water Supply Project http://www.amwater.com/caaw/customer-service/rates-information/regional-desalination-project.html

See also

Disclaimer

This page may contain student work completed as part of assigned coursework. It may not be accurate. It does not necessary reflect the opinion or policy of CSUMB, its staff, or students.