Why better policies are needed for sewage water use in thermal power plants

Power generation is a water-intensive process. In 2019 alone, approximately 36.5 billion cubic metres of water was withdrawn in the country to cater to the power needs of 1.33 billion people. With growing water stress, incidences of power plant shutting down due to unavailability of water have been increasing.

A 2018 report by Water Resources Institute (WRI) indicated that “water shortages are hurting India’s ability to produce power” and that “40 per cent of the country’s thermal power plants are located in areas facing high water stress”.

At least 14 of the 20 largest thermal power plants had to shut their operations at least once due to shortage of water between 2013 and 2016. The crisis is especially aggravated during summers when rising power demand, due to increasing cooling needs, adds further load on thermal power plants. Monsoon failures and droughts also add to the stress.

To address the situation, with the tightening the thermal power water norms in 2015, the Union government has been exploring other options to prudently satiate power plants' water needs, and one option being considered is the use of treated sewage water.

On January 20, 2016, the Union Ministry of Power (MoP) amended the Power Tariff Policy of 2006, requiring thermal power plants within 50 km of a sewage treatment plant (STP) to use treated sewage water. It was decided that the associated cost on this account would be allowed as a pass-through in tariff.

However, policy could not effectively materialise on field. According to the MoP reply in Lok Sabha in December 2018, only 1,179 million litre per day (MLD) of STP water is available for TPP, out of which 250 MLD of STP water is currently utilised.

This means, only 5 per cent of the total treated sewage (23,000 MLD) in India is available for thermal power plants within 50 km, out of which, till December 2018, TPPs were able to utilise only one per cent of the total treated water.

Understanding the considerable delay happening in sewage utilisation in thermal power plants, the MoP slightly tweaked the accountability in March 2020 to ensure sewage water be used by the thermal power plants. Reasons for poor utilisation of sewage water considered was the confusion between municipal corporation and power plants to set up pipelines and tertiary treatment plant and setting up the charges for water.

In a 2016 tariff policy, two options were provided (see table below). It was seen when municipal bodies laid the infrastructure (eg, pipes) and recovered the cost by levying tariffs on each kilolitre of water, there were disputes regarding the rates. Considering this, the MoP set the accountability for pipelines from STP to powerplant, pumping water and tertiary treatment to thermal power plants only.

However, power experts believe that the situation will not change much on the field despite policy modification. With changes in accountability to power plants, they would need to install tertiary treatment facility at their own premises, as installation of tertiary treatment plant at the STP would be difficult due to land ownership issues.

Installing tertiary treatment at STPs instead of power plants will have some economic and environmental benefits; tertiary treatment rejects 10-30 per cent of input water and rejecting waste water at the STP itself will significantly reduce the pumping cost.

Second, STPs can be better equipped than power plants to handle reject waste water from tertiary treatment.  

Looking from a broader perspective, utilisation of sewage water is already restricted due to its availability near power plants and poor water policy framework in the states. According to the Central Pollution Control Board (2016), waste water generated in India was around 62,000 MLD, out of which 23,000 MLD was being treated in 920 sewage treatment plants across the country.

According to a report by non-profit Greenpeace International, less than 15 per cent of the total coal power plant capacity dependent on freshwater had a sewage treatment plant within 50 km of their location.

This is because large sewage treatment facilities are usually located near large urban areas while coal power plants are mostly located near coal mines or in regions where land and water is available at lower costs, which, again, are usually far away from urban regions.

As sewage water demands of power plants cannot be met fully, there is a need to maintain their existing freshwater supply to do so.

“There are currently no incentives in several states for thermal power plants to replace their freshwater usage with treated sewage water. Ineffective policies are leading to lack of positive ground results,” said Sugandha Arora, programme officer, Industrial Pollution Unit, Centre for Science and Environment.

She added that in states where fresh water charges for industries were high and where there was acute water stress, industries were coming forward to buy water from sewage treatment plants.

“The need of the hour is to formulate effective water policies for the water guzzler,” she said. 

Water conflicts are set to increase with growing water demand within various sectors. Industrial sectors, especially power plants, will face the major brunt of this conflict. It is matter of survival for thermal power plants and only a comprehensive approach towards water can save their future.

Ensuring compliance to water norms in thermal power plants, innovating cooling technologies to minimise water use in water scare regions; rapidly upscaling the capacity for sewage treatment; rationalising fresh water charges in states to make treated water use viable, can be a few steps in moving towards a better future.   

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