Status of Global Fresh Water Resources
Fresh water resources around the world are coming under increasing stress due
to rising populations, economic growth, and climate change impacts like
drought. Currently, over 1.1 billion people globally lack access to water and a
total of 3.6 billion face water scarcity for at least one month each year
according to the UN. As demand increases and supplies dwindle, communities are
seeking new sources of fresh water to meet their needs.
Global Water Desalination: Process and Technologies
Global Water Desalination
is
the process of removing salt and impurities from seawater or brackish water to
produce fresh water suitable for drinking or irrigation purposes. There are two
main desalination technologies currently used - thermal distillation and
membrane processes. Thermal distillation works by evaporating seawater and then
condensing the vapor to collect fresh water. It is an energy intensive process.
Membrane desalination technologies like reverse osmosis (RO) use semi-permeable
membranes to separate salts from water through applied pressure. RO is now the
dominant desalination method due to lower energy usage. Other emerging
technologies include forward osmosis, electrodialysis, and solar-powered
desalination.
Currently, over 17,000 desalination plants are operating globally, with total nominal capacity of around 78 million cubic meters per day. The majority of this infrastructure is located in the Middle East and North Africa region which hosts over half of global capacity. Saudi Arabia alone accounts for around 25% of total capacity and is planning additional large investments to diversify its water sources beyond depleting aquifers. Other leading desalting nations include the United Arab Emirates, Spain, China, and Australia. The largest desalination plants now can produce over 200,000 cubic meters per day, indicating the scale-up of infrastructure to serve major population centers.
Potential for Expansion and Challenges
While desalination still only covers a small fraction of global fresh water demand currently, its potential for expansion is huge. According to forecasts, total global desalting capacity could rise five-fold or more by 2050 to meet growing gaps between supply and demand. Major drivers will include rising populations in coastal cities as well as countries lacking adequate renewable water resources. Desalination also offers a climate-independent source. However, key challenges to future expansion include high energy use which drives up the cost of desalinated water. Environmental concerns around brine disposal must also be addressed. Technologies advancing solutions to these issues will unlock greater potential. Financial barriers exist as well, requiring large capital outlays for infrastructure that decades to pay off. Overcoming these hurdles will determine how widely desalination can supplemented limited natural freshwater endowments in the coming decades.
Desalination Takes Off in California
The state of California has shown how desalination can play an increasing role in urban water portfolios amid growing scarcity challenges. Facing severe droughts in recent years that depleted major reservoirs to record lows, the state accelerated planning for several large coastal desalination plants. The Carlsbad Desalination Plant came online in 2015, producing 50 million gallons of fresh water per day for the San Diego metropolitan region. It was the largest desal plant in the Western Hemisphere at the time. Additional major facilities are under development near Los Angeles and Monterey. By diversifying its water sources and taking advantage of its ocean access, California aims to boost drought resilience through desalination. Going forward, the technology's integration with renewable energy could lower costs and drive further adoption.
Potential Global Water Desalination Markets and New Applications
Beyond supplying drinking water to cities and industry, desalination may also expand into new market areas. Agricultural irrigation represents huge potential globally as nearly 70% of freshwater withdrawals go to farming. However, the higher salt concentrations of brackish groundwater require different technologies than seawater. Portable or modular desalination units could supply remote mining or oil/gas operations, military bases, or emergency relief situations. There is also growing interest in small-scale household units for the poorest countries. Novel approaches include integrated solar desalination-greenhouse systems to co-produce fresh water and crops. With continued innovation, desalination capacity may be tapped for many non-traditional uses alongside traditional municipal/industrial water supplies as scarcities intensify in this century.
The Road Ahead for Sustainable Desalination
As freshwater shortages and population growth collides over the coming decades,
desalination will very likely continue its rapid rise globally as a
climate-independent source of new water supplies. However, realizing
desalination's massive potential sustainably requires further reducing energy
needs through technology, powering plants with renewable energy when possible,
and developing innovations to minimize environmental impacts. Integrating
desalination planning into broader water management will optimize use of all
sources. With the right policy and investment framework, desalination can play
a major long-term role in meeting escalating global demand for fresh water
while protecting public health and ecosystems. Concerted action is now underway
internationally to ensure this strategic resource is deployed responsibly well
into the future.
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