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Using treated sewage water for power plants impractical, says new report

The power ministry made it mandatory for plants located within 50 kms of sewage treatment plants to use treated wastewater.

health Updated: Jun 13, 2017 18:21 IST
Coal power plants require large quantities of water to function,. The government is proposing using  treated sewage water  to meet some of the demand.
Coal power plants require large quantities of water to function,. The government is proposing using treated sewage water to meet some of the demand.(HT File Photo)

The power sector is a water guzzler and this is a problem in a water stressed country like India. However, a new Greenpeace report claims that the power ministry’s proposal to use treated wastewater in coal plants is a not viable solution.

Coal plants use as much as 3.5 litres of water for every unit of energy produced, according to the report. Plants use freshwater for two major uses: to run the turbines and for cooling. The latter accounts for 80% of the total water consumption of thermal power plants.

This water has to be treated because untreated or saline water can lead to corrosion of the turbines or lead to biological growth that clogs up water channels. Thermal power plants usually get freshwater and use it after clarification.

The Power ministry last year made it mandatory for coal power plants that are located within a 50km radius of a sewage treatment facility to use treated water.

Even water that is treated by sewage treatment plants will need to undergo tertiary treatment at the plant. Buying treated wastewater from the municipal bodies will add to the cost of operation. The report claims that buying treated wastewater and installing infrastructure for its further treatment would push costs up by as much as 300 to 600 % and the cost is likely to be passed on to the consumer.

Because the sewage treatment capacity in India is so low. Less than 40% of sewage generated even in urban areas can be treated with existing facilities. Almost 86% of plants will not have access to treated sewage plants in the first place, Jai Krishna, the author of the report said, so it doesn’t really solve the larger problem of ensuring that coal power plants have ready access to water even when there is acute scarcity of freshwater.

The analysis included operational power plants with an installed capacity of 172.1 GW. The total installed capacity of operational power plants in India is 206 GW

“To claim that the use of sewage would solve coal power’s water problem would be like claiming a drop of water will save a man dying of thirst,” Jai Krishna, Greenpeace researcher and author of the report, said.

The author also said that diverting treated sewage water for use in power plants also has ecological impacts because it limits return flows into rivers and other surface water bodies. Even if it is not used for drinking the sewage water goes back into circulation instead of being stashed away for power generation.

Power ministry officials were not immediately available for a response. The government’s proposal attempts to tackle two problems in one go. It tried to ensure assured water supply for power plants while improving sewage treatment facilities. If municipalities find consumers who are willing to pay for the treated water they will be incentivised to improve their sewage treatment facilities.

The policy will have such a limited impact that it will fulfil neither objective while adding to costs and cause possible ecological damage, the report said.