The Earth is often called the “Blue Planet” due to its vast oceans, which cover over 70% of its surface. Despite this vastness, fresh water is increasingly scarce for human consumption. By 2030, global freshwater demand is predicted to exceed supply by 40%, highlighting a significant challenge for communities worldwide. Given that oceans hold most of the planet’s water, why can’t we simply use this abundant resource?
The Salinity Barrier
Ocean water is unsuitable for direct human use due to its high salinity, containing a significant concentration of dissolved salts. Seawater typically contains about 3.5% dissolved salt by weight, primarily sodium chloride, a concentration too high for safe human consumption.
When seawater is consumed, its high salt content makes the bloodstream saltier. Kidneys must work excessively to remove this excess salt, requiring more water than consumed, leading to dehydration. Continued consumption intensifies dehydration, causing severe health issues like dizziness and confusion.
High salinity also poses problems for agriculture and industrial processes. Saltwater irrigation leads to soil salinization, making land infertile and damaging crops by drawing water from plant cells. In industrial applications, saltwater causes corrosion and scaling, reducing efficiency and increasing maintenance costs.
Desalination’s Hurdles
Desalination, the process of removing salt from ocean water, offers a potential solution to freshwater scarcity, but faces practical challenges. Common methods like reverse osmosis and thermal distillation are energy-intensive.
This energy requirement translates into high operational costs. Building and maintaining large-scale plants also demands financial investment. These facilities require specialized infrastructure for water intake, output, and distribution. The cost of desalinated water is higher than from conventional sources like rivers or groundwater.
Operating these facilities requires specialized expertise and continuous maintenance. Reverse osmosis membranes can foul, requiring cleaning or replacement, and machinery needs consistent monitoring for efficient operation.
Ecological Considerations
While desalination provides fresh water, its large-scale implementation raises environmental concerns, particularly regarding brine disposal. Brine is the leftover hypersaline water, containing high concentrations of salts and sometimes chemicals.
Discharging brine into marine environments can increase local water salinity, harming marine organisms not adapted to such conditions. Increased salinity and reduced oxygen in discharge areas can disrupt marine ecosystems, impacting biodiversity and altering habitats. Intake systems also threaten marine life.
Organisms, from small fish to plankton, can be drawn into intake pipes (entrainment) or trapped against screens (impingement), leading to injury or death. Desalination’s energy demands also contribute to its carbon footprint. If powered by fossil fuels, it leads to increased greenhouse gas emissions, exacerbating climate change. This environmental impact presents a dilemma: while desalination addresses water scarcity, it can also contribute to ecological challenges if not managed sustainably.