DESALINATION

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Context: While the technology to convert ocean water to fresh water is not new, it has not been a viable solution for most regions due to its high economic and environmental costs.

Details: 

The challenges:

• Uneven distribution of finite sources of water:
• While around 70% of Earth’s surface is covered with water, less than 1% percent is actually drinkable.
• In hot, dry regions with growing populations and increasing living standards, there is not enough water to go around — a situation exacerbated by climate change.
• Water poverty is set to worsen as populations increase along with temperatures, with Sub-Saharan Africa predicted to become a “hotspot of water scarcity” by 2050.

About Desalination:

• The centuries-old concept uses thermal distillation or a reverse osmosis membrane to separate salt from the sea.
• Costs have “decreased tremendously” — from around $5 ($4.69) per cubic meter (1,000 liters) in the 2000s to 50 cents today.

Alternatives: solutions such as cloud seeding or even iceberg harvesting remain unproven at scale.

Global use:

• The technique is now being utilized globally, with well over 20,000 desalination plants currently operating in over 170 countries — the 10 largest in Saudi Arabia, the United Arab Emirates (UAE) and Israel.
• Around 47% of the world’s desalinated water is produced in the Middle East and North Africa alone.
• The hottest and driest nation in the EU, Cyprus relies on desalination for 80% of its drinking water.

Marine and climate impacts of desalination:

• Separating salt from water is highly energy intensive.
• Four desalination plants in Cyprus generate around 2% of its total greenhouse gas emissions.
• The plants also accounted for 5% of the total electricity consumption in Cyprus, representing one of the largest shares by sector of electricity consumption.
• Highly toxic brine: Desalinated water produced generated around 103 million cubic meters of toxic, high-salinity brine effluent that impacted the Mediterranean seagrass ecosystem in the region of the discharge pipes.
• Increased salinity, combined with climate-driven temperature rise, can cause a decrease in the dissolved oxygen content, resulting in conditions called hypoxia.
• This hypersaline water can sink to the ocean bed and kill marine microorganisms that are vital to the entire food chain.
• In addition, chemical compounds such as copper and chloride are also observable in the desalination pre-treatment process and can be toxic to organisms in the receiving water

Solutions:

• A Berlin-based company, Boreal Light, has developed off-grid solar and wind energy desalination plants that ensure greater energy independence and immunity from price fluctuations.
• Sodium, magnesium, calcium, potassium, bromine, boron, strontium, lithium, rubidium and uranium could be harvested from the filtered material and reused in industry and agriculture.
• MIT Scientists have suggested ways to repurpose brine by using the salt to produce caustic soda, or sodium hydroxide.

 

PRACTICE QUESTION Q) Despite being highly energy intensive and environmentally toxic, Desalination is the obvious way to go. Comment.  (150 words)

 

https://indianexpress.com/article/explained/explained-climate/is-ocean-viable-solution-for-water-scarcity-8514631/