Chennai

Thermal plants: emission norms a blow to Tangedco

The proposal of the Ministry of Environment, Forest and Climate Change (MoEFCC) to bring in certain modifications to pollution norms for coal-based thermal power plants is bound to adversely impact Tamil Nadu Generation and Distribution Corporation (Tangedco) financially.

The notification issued by the Environment Ministry seeks to amend the Environment (Protection) Rules, 1986, setting standards for existing and new coal-based thermal power plants to be commissioned after January 1, 2017, on water consumption and emission limits of particulate matters.

With Tangedco having more than 5,000 mega watt (MW) capacity of thermal power plants in the State, senior officials said they will object to the Ministry’s new provisions. The norms have been arrived at without considering the high ash content prevalent in Indian coal when it comes to particulate emissions and the subsequent costs for constructing cooling towers to remove heat from the discharged water.

A senior Tangedco official says except Mettur Thermal Power Station (MTPS) Stage 2 (1x600 MW), which has cooling towers, the six thermal power stations including MTPS Stage 1, Ennore, Tuticorin, North Chennai Stage 1 and 2 and ST-CMS (Neyveli), would have to create capital outlay of more than Rs. 2,500 crore for constructing such towers. The estimated cost to construct one cooling tower is around Rs. 200 crore, he points out.

All these plants operated under ‘once through cooling (OTC) technology’ and conform to prevalent pollution norms fixed by Central Pollution Control Board (CPCB). North Chennai and Tuticorin thermal power stations located in coastal regions have been drawing only sea water, that too from the port. Regarding water consumption he explains that NCTPS Stage 1 draws 90,000 cubic metre per hour and two lakh cubic metre per hour for Stage 2.

Citing that pre-cooling channels (that reduces heat by 2 to 3 degrees) have been provided for NCTPS, he brings to focus, the advantages of maintaining the ecological balance in Ennore Creek by letting huge quantity of heated water into the creek instead of being let out directly into the sea.

Highlighting there were no norms for Sulphur dioxide (SO2) and Oxides of nitrogen (NOx) emission previously, the new emission limits that would come into force in 2017 have fixed parameters for particulate matter. It has set standards under three categories – thermal power plants installed before December 31, 2003, those installed between December 31, 2003, and Decmber 31, 2006, and power plants to be commissioned from January 1, 2017.

While the new norms have fixed 100 milligram per normal cubic metre for particulate matter, 200 milligram for So2 and 600 milligram for NOx (units having capacity of 500 MW and above for TPPs installed before December 31, 2003), Stage 2 of both North Chennai and Mettur plans emit 50 milligram for particular matter. Similarly NCTPS Stage 2 has recorded emission for So2 and NOx of less than 100 milligrams. He also picked holes regarding the emission of particulate matter of 30 milligram for new plants to be installed from January 1, 2017, which can never be achieved because of high ash content prevalent in Indian coal.

Stating that the Ministry has brought the subject of mercury emissions for the first time, the official said tests conducted in the past found no trace of any mercury in the coal.

What's the issue?

The notification issued by MoEF for coal-based thermal power plants under the Environment (Protection) Act, 1986, regarding water consumption and emission norms would take effect in the year 2017.

 

A tangled path

Installing cooling towers in the existing coal-based thermal plans could cost dearly. A cooling tower costs around Rs. 200 crore

While considering the particulate matter, the MoEF has not taken into consideration the large ash content present in Indian coal, which is one of the reason for higher pollution.

Regarding bringing down sulphur dioxide, installing a flu gas de-sulphurisation plant would bring the sulphur content to almost nil. But the plant would require huge quantities of limestone and the byproduct Gypsum would be hard to dispose off

The North Chennai Thermal Power Station (Stage 2) and Mettur Thermal Power Station (Stage 4) has already achieved 50 mg/Nm3 against the proposed 100 mg/Nm3                     

Standards recommended for water consumption:

1. All plants with once through cooling (OTC) shall install cooling towers and achieve water consumption maximum four million cubic(mc)/MWh (mega watt per hour) within 2 years.

2. All existing coal-based thermal plants shall reduce specific water consumption upto max. of 3.5 mc/MWh within 2 years.

3. New plants to be commissioned after January 1, 2017, shall meet specific water consumption max. of 2.5 mc/MWh and achieve zero liquid discharge.

Standards recommended for particulate matter:

1. 100 mg/Nm3 (for plants installed before Dec. 31, 2003)

2. 50 milligram (mg)/Nm3 (Normal cubic meter) (for plants installed between Jan. 2004 and Dec. 31, 2006)

3. 30 mg/Nm3 (for plants to be installed from January 1, 2017)  

Standards recommended for sulphur dioxide (SO2)

1. 100 mg/Nm3 (for plants of 500 MW and above and installed before Dec. 31, 2003)

2. 200 mg/Nm3 (for plants installed between Jan. 2004 and Dec. 31, 2006); 

3. 100 mg/Nm3 (for plants to be installed from January 1, 2017)

Standards recommended for Oxides of Nitrogen (NOx)

1. 600 mg/Nm3 (for plants installed before Dec. 31, 2003)

2. 300 mg/Nm3 (for plants installed between Jan. 2004 and Dec. 31, 2006);

3. 100 mg/Nm3 (for plants to be installed from January 1, 2017)


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Printable version | Oct 23, 2021 8:44:06 PM | https://www.thehindu.com/news/cities/chennai/thermal-plants-emission-norms-a-blow-to-tangedco/article7339525.ece

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