Desalination plants harm environment: UN

Desalination plants harm environment: UN

Context: Prevailing drinking water crisis in India and the prospect of desalination technology in India.

Availability and access to improved source of drinking water is a basic indicator for human development and bears direct relevance to health and well-being of individuals.

Availability of drinking water in India is falling:

• Between 2001 and 2011, there has been a significant decrease in use of wells (22.0 %), as a major drinking water source, indicating fall in ground water tables.
• Per capita annual availability of water in the country is expected to fall from 1860 metre cube a year in 2001 to 1140 metre cube a year by 2050.
• Niti Aayog report warns that 21 cities are likely to run out of groundwater by 2020. Report estimates that demand will be twice the availability by 2030 and water scarcity would account for a 6% loss in India’s gross domestic product (GDP).
• Rural areas also cannot rely on groundwater due to erratic rains and the fact that the groundwater is increasingly used for farming when monsoon rains are delayed or insufficient.

Considering above problems, using seawater, that most coastal states have access to, can be an effective solution. India’s National Water Mission identifies desalination as a major tool to make sea water and brackish water accessible and usable for the people. India already has desalination plants but to bring uniformity in the field of water desalination in the country the Union government is working on a new mission on desalination.

Desalination: Desalination essentially means removing salt and other minerals to make water fit for drinking or other purposes. The filtration of saline water can be done through Thermal Desalination Technology or Membrane Technology like Reverse Osmosis (RO).

Australia, Caribbean Islands, the Middle East, South Africa, USA, etc are some other countries that have established large desalination plants for domestic use. Israel now gets 55 percent of its domestic water from desalination and is helping India to set up desalination plants.

Gujarat and Tamil Nadu have the highest installed capacity of desalination in India. Chennai’s one-third water demand is met by two desalination planta of Minjur and Nemmeli, churning out 200 million litres of water per day (MLD).

Challenges posed by desalination plants:

• Environmental and human rights issues: the discharge from desalination plants i.e. brine, comprises about 5% salt whereas global seawater has 3.5% salt.
• The brine reject tends to create a sort of niche microhabitat with higher levels of salinity around areas where they are let out.
• Brine can cut levels of oxygen in seawater near desalination plants with “profound impacts” on shellfish, crabs and other creatures on the seabed.
• Brine water often contains toxins like chlorine and copper used in desalination.
• Brine reject from the plant is often let out directly onto the beaches and near coastlines, thus eroding the coastline and the livelihoods of locals, in addition to turning the groundwater salty.
• Less efficient: As per a UN study, desalination plants pump out 142 million cubic metres of salty brine every day, to produce 95 million cubic metres of fresh water, thus increasing the overall salinity of the oceans.
• High energy cost: Desalination plants are highly energy-intensive and capital intensive. Using coal to heat saline water means thousands of tonnes of carbon dioxide is produced in a 100 MLD plant.
• Lack of monitoring of plants: India does not have standards for governing the brine concentration entering the sea, nor the EIA process is followed during planning a plant, which allows companies running desalination plants to escape responsibility.

Following steps may help in increasing the viability of desalination in India:

• Using alternate energy sources: Using cheaper forms of energy other than electricity like solar power, wind energy etc. Big ponds of saltwater can use solar heating directly for desalination as done in regions in the Middle East.
• Salt extraction: Brine is rich in salt content which can be harnessed for extraction of salt by setting up adequate infrastructure near desalination plants.
• Pumping brine underground: Instead of flushing brine near coastal areas, it can be channelized and stored underground or piped deep into ocean.
• Alternate technologies: Setting small viable plants catering to small areas like individual villages using a different desalination technology called electrodialysis, powered by solar panels, could provide enough clean, palatable drinking water to supply the needs of a typical village.
• Legal framework: Harnessing of sea water resources should be included in the draft National Water Policy framework released in 2016, with legal safeguards and provisions for management of desalination plants.
• Exploring other options: Water rich states like Tamil Nadu receive ample rainfall from the monsoons and might not need large scale desalination plants. To meet drinking water needs of cities, conserving and protecting lakes and wetlands is a cheaper and environmentally better option than desalination.