The thermal plants in Ballari and Raichur that power Karnataka can cut costs by using waste water thus reducing the stress on fresh water in the two cities where people get less water than the standards fixed by the Union government, a new study by researchers from the National Institute of Advanced Studies (NIAS) says.
The study on urban water-energy nexus noted that people in Ballari and Raichur get 100 litres per capita per day (lpcd), which is much lower than the 135 lpcd stipulated by the Ministry of Housing and Urban Affairs. Both cities are located within the vicinity of water-guzzling thermal power stations (TPS).
Raichur TPS has installed capacity of 1,720 MW, Yeramarus (1,600 MW), Ballari TPS (1,700 MW) and JSW captive power plant has installed capacity of 860 MW. Except for the JSW plant, the water demand in thermal plants is “substantially” higher than the stipulated value of 3.5 cubic metre per MW.
Water shortage has also affected the TPSs, leading to partial shutdown of RTPS for 60 days in 2016 and partial shutdowns of BTPS for 98 days in 2017-18. As TPSs make for 72 per cent of the electricity generated in India, the study said: “There is an urgent necessity to ensure reliable TPS operations which is critical for providing affordable power to all,” it said.
Sherin S Das, Rudrodip Majumdar, A V Krishnan and R Srikanth from the Energy, Environment and Climate Change Programme, NIAS, tried to look at the water demand in Ballari and Raichur with an integrated approach to address the future needs of the growing cities.
Urbanisation and power demand
Noting that urbanisation will lead to higher demand for power and water, the study pushed use of treated water as a sustainable measure.
The researchers cited the example of Koradi TPS (1980 MW) in Nagpur which gets treated water at a cost of Rs 3.73 per cubic metre, less than half of the freshwater cost of Rs 9.6 per cubic metre. “This amounts to capital savings to the tune of Rs 23 crore and fresh water savings of 40 million cubic metre per year,” the study said.
By 2050, the population of Ballari city is projected to reach 9.2 lakh and the city’s domestic water demand will hit 124 mld. The water supply potential of the municipal corporation, however, will be limited to 85 mld after 15 per cent losses during supply.
Raichur will see its population reach 3.67 lakh with a need for 50 mld water but the water supply potential will be limited to 39 mld after 15 per cent losses during supply.
The TPSs and industries in the two cities will also see a rise in demand for water by 2050. Ballari TPS and industries will require 74 million cubic metres (MCM) of water annually while the Raichur TPS and industries will need 40 MCM annually.
The cost factor
Acknowledging the huge costs involved in building treatment plants, the study proposed that the urban local bodies, obliged to treat wastewater, should be allowed to enter into an agreement with TPS that can construct the treatment plants and the cost of the treatment can be borne by TPS.
The study said BTPS can save Rs 8.8 crore per annum in 2030 and Rs 12.6 crore per annum in 2050 at current price of treated water. YTPS could save Rs 6 crore and Rs 8 crore per annum in 2030 and 2050, respectively it said. This will in turn save freshwater which could be diverted for domestic consumption.
“The extent of additional allocation to cater to the domestic requirement could be 9.8 MCM per annum for Raichur city and 14 MCM per annum for Ballari municipal town area by 2030. This will translate to an additional 30-40 lpcd of drinking water availability for city dwellers,” it said.
To a question, corresponding author Rudrodip Majumdar said the use of treated wastewater will become even more important if water resources become scarce due to climate change.
“The price of treated wastewater should be substantially lower than that of freshwater. Then only the industries will be attracted towards using treated municipal wastewater,” he said.
On the possibility of using secondary treated water, he said though tertiary treatment is expensive, TPSs have certain water quality expectations for different processes which cannot be compromised. “For example, if the treated water is used in the cooling towers, the water quality requirements will be higher, whereas, secondary-treated water would do fine for ash handling. Power plants have to make these choices based on the quantum of the treated wastewater available in a regular manner,” he said.