Mumbai: The Bhabha Atomic Research Centre, or Barc, has built a barge-mounted desalination plant that can produce 50,000 litres of drinking water everyday. Desalination essentially means removing dissolved salts from sea and brackish water. Built as a technology demonstrator, the plant is currently docked near Goa and ready to sail.
“It is being transferred to the mining and mineral processing company, Indian Rare Earths Ltd, which will deploy it in one of its locations,” says P.K. Tewari, head, desalination division of Barc.
Safe drinking water is an unrealized dream for people in many parts of India, particularly in the coastal regions that have either sea or brackish water as their only source. The problem gets worse when natural calamities, recurrent along the country’s 7,517km-long coastline, disrupt the drinking water system.
A barge carrying Barc’s desalination plant, which can produce 50,000 litres of drinking water every day. Desalination essentially means removing dissolved salts from sea and brackish water
The idea behind Barc’s initiative was to test a “unique sustainable model” of water entrepreneurship where Barc would supply the technology and guidance, and the entrepreneur would bring in capital and devise a price mechanism, whereby he could repay his loan (if any, on his capital), make marginal profits and fulfil consumer needs.
Globally, even though desalination is gradually gaining ground as one of the means to tide over water shortage, its biggest downside is its energy-intensive nature. While renewable energy is being tested in some places, it’s still a few years away from running large plants. But Barc, which runs its barge unit with diesel to push water through a polyamide membrane to leave behind the salts, seems to have done its math.
A cost of about 12 paise per litre and around 10 litres per capita/day of usage (3 litres for drinking, 7 litres for cooking) makes this not a heavy price to pay even for rural areas, argues Tewari.
“With this calculation, our plant could serve a habitation of 5,000 people,” Tewari says. He thinks it’s ideal for disaster zones, places such as Lakshadweep, a cluster of 36 islands where there is almost no fresh water to be had, and the Rann of Kutch, one of the most arid area of India and the world.
There are not many barge-mounted public use desalination plants in the world today. Two such shore-based plants, each with a capacity of 26 million litres/day, are operational in Jeddah in Saudi Arabia, says Tom Pankratz, a director at the International Desalination Association (IDA) and desalination consultant in Houston, Texas.
But for the first time, Texas-based Water Standard Co., is building a 75 million litres per day desalination plant on an ocean-going ship.
Besides supplying water in critical situations, “barge- mounted plants have some construction and some cost advantages,” says Pankratz. Sometimes just access to seawater is a difficult issue; in other cases, constructing plants in remote areas where skilled labour is scarce.
But the system has its downsides. It’s not as easy as it sounds, says Pankratz. Even though the barge is located fairly close to the shore, off-loading capabilities still need to be developed. “Barge-mounted plants cannot always benefit from economies of scale and diesel is often not the most effective energy source,” says Pankratz.
Still, the drivers of desalination today are economics and environmental concerns. Research firm Global Research Insights estimates that between now and 2015, the desalination capacity in the world will almost double. According to IDA, about 13,080 desalination plants are operating today with a capacity of 55.6 billion litres/day.
Barc has an exhaustive desalination programme, which includes nuclear, thermal and membrane-based systems. Nuclear desalination units use waste heat from the nuclear power plants to process seawater. In thermal desalination, low-grade or waste heat from industry (or generated on-site) is used for desalination, whereas membrane-based systems use different types of pressure-driven semi-permeable membranes to filter dissolved salts from the brackish or seawater.
However, the barge-mounted plant derives from experiences gained from two seawater reverse osmosis systems that are installed at Barc’s Trombay campus in Mumbai and Indira Gandhi Centre for Atomic Research in Kalpakkam, near Chennai. Keeping safety in mind, the desalination vessel is certified by the Indian Register of Shipping so that it can be easily sailed from one place to another.
Now, the technology demonstrator has to make business sense so that more such barges can cruise out of Barc.