California Desalination Report With More Than A Grain Of Subjectivity Part 2

By Author: Nikolay Voutchkov
Total Articles: 76
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Is desalination affordable for Californians?
The PI report indicates that one of the major reasons for California desalination's ‘immaturity' is its lack of affordability. Currently, the cost of desalinating seawater in California is relatively higher than that of traditional low-cost water sources (groundwater and river water) and water reclamation and reuse for irrigation and industrial use. Indeed, the cost of traditional local groundwater water supplies in some parts of the state
is as low as $0.5/1,000 gallons ($160/acre foot [AF]). However, the quantity of such low-cost sources is very limited (less than 30 percent of water resources statewide). For example, notwithstanding that over 40 percent of the current Orange County water supplies are in this category, that county's water agencies have embarked on exploring seawater desalination because practically all available fresh aquifers currently delivering this low-cost water are tapped-in and over-drafted. Most of the utilities in southern California currently purchase imported water
from the Bay Delta and Colorado River at a rate of $1.5 to 1.8/1,000 ...
... gallons ($500 to $600/AF) and the cost of these water supplies is very likely to increase by 10 to 15 percent in the next five years due to additional expenditures needed to comply with more stringent drinking water
quality regulatory requirements recently promulgated by the US EPA.

Based on the 2006 California Water Charge Survey published in July 2006 by Black & Veatch (http://www.bvaeservices.com/news/articles/jul06/ca_ survey_businesswire.htm), the average residential monthly charge for 1,500 cubic feet
of drinking water was $36.39 ($3.24/ 1,000 gallons or $1,058/AF). The survey also indicates that the cost of residential water supply has increased by 16.7 percent since 2003.

Meanwhile, the cost of desalinated water has been decreasing steadily over the last 10 years and the majority of the projects included in the California desalination initiative, declared premature by the PI report, are projected to produce water at a cost of $2.6 to $3.7/1,000 gallons
($850 to $1,200/AF). These costs are estimated based on an asset life of 30 years and unit power costs of $0.08/kWh to $0.11/kWh. Therefore, if we follow the gem of advice in the PI report that, cost comparison must be made on comparable basis, then the costs for production of desalinated seawater would be similar to the future total costs for delivery of new incremental water supplies to many parts of the state, especially to municipalities and utilities in southern California relying on imported water supplies.

The PI report uses the argument that desalinating seawater and brackish water is generally more expensive than the production of reclaimed water and the implementation of water conservation measures. This argument however, is fatally flawed by the fact that water conservation
and reuse do not create new sources of drinking water—they are merely a rational tool to maximize the beneficial use of the available water supply resources. Under conditions of prolonged drought when the available water resources cannot be replenished at the rate of their use, aggressive reuse and conservation can help but may not completely alleviate the need for new water resources and water rationing. Simply
put, if your backyard well is dry you cannot resolve your household water supply challenges by reusing or conserving more of the well water you do not have.

A real-life example is the period of prolonged drought in California in the early ‘90s, which created the need for emergency fast-track implementation of a number of water desalination projects, despite the fact that some municipalities, such as the City of Santa Barbara, had
reduced their water use by nearly 40 percent by aggressive conservation measures. While the relatively high cost of seawater desalination ($4.6 to $6.1/1,000 gallons or $1,500 to $2,000/AF) and the available low-cost reclamation and reuse measures combined with a period of several
wet years following that long drought marginalized the benefits of seawater desalination at that time, the water conditions, costs and challenges
California faces today are very different.

The main differences stem from the significant reduction of the costs for seawater and brackish water desalination over the last 10 years and the incrementally higher costs associated with achieving dramatic increase in water reuse and conservation statewide after the initial set of low-cost/high-effect water reclamation and conservation measures are implemented. While in the early ‘90s extensive conservation and reuse were uncommon for the majority of the municipalities in California, the prolonged drought during this period forced many utilities to implement lowcost
water reuse and conservation measures that now constitute 5-15 percent of their water portfolios. Utilities which already have comprehensive water reuse and conservation programs will not be able to squeeze another 10 or 15 percent of water savings via the same low-cost reuse and conservation measures. Implementing the next tier of more sophisticated equipment and technology-intensive reuse and conservation measures to reach water-saving goals of an additional 20-25 percent comes at a price which, in some cases, may approach that of desalination.

In addition, seawater desalination cost benefits extend beyond the production of new water supplies. If desalination is replacing the use of over-pumped coastal or inland groundwater aquifers, or is eliminating further stress on environmentally sensitive estuary and river habitats, then the higher costs of this water supply alternative would also be offset by its environmental benefits. Similarly, desalination provides additional
benefits in the time of drought where traditional water supplies may not be reliable and their scarcity may increase their otherwise relatively low costs.

Will desalination ‘break the back' of California's power supply system?

Desalination is more power intensive than conventional treatment of fresh water sources because it requires additional energy to overcome the naturally occurring osmotic pressure exerted on the reverse osmosis (RO) membranes by the saline water source (ocean or brackish
water). Table 1 presents the energy use associated with various California water supply alternatives. The table does not incorporate the costs associated with raw water treatment of the surface water imported from the Colorado River project and supplied by the State Water
Project and product water delivery costs for any of the listed alternatives.

It is interesting to note that the PI report contains a number of factual inaccuracies which indicate the authors' superficial understanding of the factors affecting the energy demand associated with seawater desalination and the contribution of power expenditures to the overall cost of water production. Based on reference to energy use of projects in Israel, the Middle East and Spain, where ocean water has approximately 20 percent higher salinity than the Pacific Ocean along the California coast, the report concludes that even if best available technologies are used, the power demand for production seawater desalination will be 12 kWh/1,000 gallons (3,912 kWh/ AF). In fact, since the Pacific Ocean has lower salinity than the referenced locations, the energy needed to produce desalinated water ranges between 8.6 and 11 kWh/1,000 gallons (2,800 to 3,600/ kWh/AF).

The PI report remains silent about the outstanding efforts of the Californiabased Affordable Desalination Collaboration (ADC) which recently completed a study to demonstrate what the currently available state-of-the art desalination technology can do to reduce energy use for seawater desalination. ADC is a non-profit organization composed of leading companies and public agencies involved with seawater desalination. The
expert-reviewed results from over one year of operation of the ADC seawater desalination demonstration facility located at the US Navy's Desalination Research Center in Port Hueneme, California validate the energy consumption values included in Table 1 and also indicate that in the not-so-distant future the power use for seawater production can be reduced even further (see www.affordabledesal.com).

The PI report contains another inaccuracy with important implications regarding the viability of seawater desalination in California. Without normalizing data from foreign desalination plants for the site-specific conditions in California (labor, construction, equipment costs, etc.) the report stipulates that electrical energy accounts for 44 percent of the total water production costs of a typical membrane seawater desalination
plant and 60 percent of costs for thermal water desalination. In fact, due to site-specific differences, the power costs for seawater desalination in California would contribute only 20-30 percent of the total costs of water production. The PI report draws the erroneous conclusion that the fluctuations in international fuel markets will have a dramatic effect on the viability of desalination; it also misses the point that energy cost increases will also have the same incremental effect on all water supply alternatives in California. According to a report prepared by the
California Energy Commission, the current power demand of the water sector in California (including both water and wastewater conveyance and treatment) totals 13,341,000 mWh. Assuming a conservative unit energy use for seawater desalination of 11 kWh/1,000 gallons, the
total energy needed to produce 450 mgd of drinking water is 4,950 mWh, which is only a 0.037 percent increase of the current California water sector energy demand. Based on these facts, it is erroneous to conclude that the current desalination initiative would ‘break the back' of the California energy supply system, nor could such be objectively used as a valid argument for rejection of the viability of seawater desalination in
California. This assessment also diffuses the PI report's claim that, desalination facilities exacerbate climate change with their large use of energy, and that it, can contribute to greater dependence on fossil fuels.

It should also be pointed out that an objective analysis of the energy use for seawater desalination should take into consideration that while the energy use for production of desalinated water is projected to decrease further (by 10-20 percent over the next five years, as a result of advancements in membrane and energy recovery technologies), the total energy demand for conventional water treatment would increase (by 15 to 20 percent) in the same timeframe because of the energy demand associated with the additional treatment (such as micro- or ultra-filtration, ozonation, UV disinfection, etc.) which would be needed in order to meet the most recent regulatory requirements for production of safe
drinking water.