Desalination in the American West
As drought conditions rage on throughout the American West, policymakers and engineers are working together to devise the solutions facing an increasingly arid landscape. The U.S. Bureau of Reclamation has recently told states in the Colorado River Basin that they have 60 days to create an emergency plan for water conservation, and all hands are on deck to craft solutions. One such proposal involving seawater desalination technology has gained traction as the frontier in water augmentation—but as with most climate solutions, its externalities could pose equally concerning ecological and economic downsides.
HOW IT WORKS
Desalination plants employ reverse osmosis technology to extract filtered water molecules from seawater. Oceanwater is forced through permeable membranes under high pressure, allowing smaller potable water molecules to pass through while leaving salter and other impurities behind its barrier.
Once water is desalinated, the excrements left behind comprise a salty brackish chemical mix harmful to the marine organisms ingesting it as well as the soil absorbing it. Desalination methods produce approximately 1.5 to 1.7 liters of salty brine per liter of freshwater, numbers far from negligible when assessing environmental impacts. If pumped back into local ocean ecosystems, this salty discharge disrupts the elemental composition of oceans and kills marine life in its wake. Additionally, marine organisms native to the seawater inlets supplying desalination plants are often killed when sucked onto the inlet covers of the desalination system through a process referred to as entrainment.
Desalination techniques are also incredibly energy intensive, consuming more than 200 million kilowatt-hours of energy each day in operation. Because energy costs comprise approximately 55% of a desalination plant’s operating costs, the market cost of desalinated water is particularly vulnerable to price increases in the energy sector. Energy costs, coupled with the costs of mitigating environmental damages, makes desalination plants an expensive investment for taxpayers.
HOW MUCH IT COSTS
Defying the basic economics of supply-and-demand, more supply via desalinated water projects doesn’t always mean lower prices for consumers. California’s Carlsbad Desalination Plant currently sells water for $2,725 per acre-foot; For scale, the Central Arizona Project that delivers Colorado River Water to Arizona farmers and municipalities charges most users $155 per acre-foot under its current rate schedule. Particularly in regions where rising costs of living are already an issue, achieving water security through the sale of expensive desalinated water is a difficult sell to the American consumer. Although in shorter supply and theoretically more expensive as a result, depleted water sources remain more cost effective in the face of desalination because its delivery and treatment infrastructure are already in place.
Desalination infrastructure presents an exorbitantly high cost of implementation up front, with the elusive promise of paying for itself in the future. On average, even a smaller scale desalination plant processing 2.5 million gallons per day runs about $32 million to construct—larger scale operations processing up to 100 million gallons per day cost about $700 million. Arizona Governor Doug Ducey recently touted plans to invest over $1 billion dollars into exploring the feasibility of desalination in the Gulf of Mexico. Were Arizona to fund such a project, Mexico in exchange would likely take less of their allocation of the Colorado River for Arizona’s use, a shared water source in notable shortage by recent calculations. Despite growing questions surrounding water security, many Arizona water users are left skeptical over rising fiscal costs if such a deal is struck.
California is already engaged in a bitter public battle over desalination. The California Coastal Commission recently rejected proposals for a $1.4 billion desalination plant in Huntington Beach after fervent public outcry regarding environmental harm and exorbitant consumer costs. If implemented, the plant’s water output would have sold at rates 400% more expensive than imported water and harvested rainwater. Many experts feel desalinated seawater in California is likely economically infeasible if sold at market value.
For many, tapping into vast ocean resources through desalination intuitively makes for sound policy, especially as sea levels continue to rise and freshwater becomes more precious. Researchers warn that the current drought in the Southwestern United States is reportedly the driest in over 1,200 years and showing no signs of stopping; theoretically, desalinated water presents near-limitless augmentation of existing freshwater sources in critical areas. In practice, however, mitigating the environmental downsides of desalination as currently understood may supersede the benefits of implementation.
Promising solutions are in the works to address desalination’s less attractive features. Researchers at MIT recently developed a prototype of a portable desalination unit that employs electrically charged membranes instead of pumps or filters, bringing attractive logistical efficiency to the scientific forefront. Similar measures for mitigating environmental problems such as evenly disbursing salty discharge across the high seas, installing protective intake mechanisms to prevent entrainment, developing sustainability projects for harnessing salty brine output, and utilizing renewable energy sources to fuel plant operations are all indications that desalination technology may be the new frontier of water development. As this space continues to evolve, however, investors and lawmakers should remain weary of desalination’s economic and environmental challenges.
Policymakers should recognize the realistic and nuanced opportunity that desalination presents. The solution to water scarcity will not be found in harnessing one miraculous source of potable H2O—rather, incorporating desalination reservedly into existing state water portfolios can balance economic costs and drive the price of desalination to more reasonable figures. Achieving water security requires a holistic approach utilizing a blend of water augmentation, conservation, and management tactics.
Climate Security in Focus is a blog series dedicated to exploring key elements of climate security that impact American interests both at home and abroad. The series aims to examine specific aspects of climate security issues in order to better understand climate policy challenges, facilitate conversation, and generate ideas.