CAG’s Comments on the Executive Summary for proposed Ennore Thermal Power Station (ETPS) Replacement TPP (1X660 MW) at Ernavur Village, Tiruvottiyur Taluk, Thiruvallur District, Tamil Nadu by M/s. Tamil Nadu Generation and Distribution Corporation Ltd. (TANGEDCO) submitted at the Public Hearing held on 30.05.2017 in the premises of the Quarters (camp-1) of M/s Ennore Thermal Power Station, Ernavoor Village, Thiruvottiyur Taluk, Tiruvallur District.

 

Subject

Issue

Comment

Existing Thermal Power Plant

Closure of existing 450 MW (3x110 MW + 2x60 MW) TPP

It has served more than 40 years and to be closed by 31.03.2017.

The past operating plant would have accumulated fly ash, bottom ash etc, greenery area, whether sea disposal system exists or not.

Impacts of project closure activities are not addressed

New Project

Expansion 1 X 660 MW supercritical technology using local Coal in existing 120 Acres (total area available is 237 acres).

Non-compliance issues pertaining to the existing thermal power plant are not mentioned in the EIA report. These must be investigated by the relevant authority.

These include past environmental issues, site situation, residual ash and any non compliance issues related to Consent To Operate (CTO).

Sea water

The total seawater requirement is 37,76,256 m3/day, daily makeup requirement is 1,32,480 m3/day

These are not in line with specific water consumption norm for coastal based power plants.

Freshwater

The fresh water requirement is 7,200  m3/day.

Construction purposes

Water required for construction purposes to be obtained from CMWSSB.

This is to be stored in an underground water tank, and from where pumped into the overhead tank for further distribution by gravity to various points.

Given the drought, CMWSSB is already having problems to supply water for public needs.

It is submitted that seawater desalination plant should be planned at the construction stage.

 

 

Coal

Local coal requirement

@ 85% plant load factor is 3 (Million Tonnes per Annum) MTPA and

@ 100% plant load factor is 3.5 MTPA.

It is not clear why different plant load factors are considered. The convention is to take 85% plant load factor and so restrict coal consumption < 3 MTPA. This should be recalculated and corrected by the project proponent.

 

Ash content

Ash content of 34% has been considered both for 100% domestic coal and blended coal of 30% imported & 70% local coal.

It is submitted that there is a legal requirement is to use coal with ash content < 34%.

It is not possible to get ash content of 34% with domestic coal. It will be far higher.

 

Ambient air quality

A 24-hour average norm for PM 10 and PM 2.5 is considered.

A 24-hour norm is lax as it takes into account only for the day.

The measurement should be against annual average (which is more stringent and that must be compared). The ambient air quality measurements should be reworked by the project proponent.

 

Particulate emission

The project proponent has to adhere to a particulate emission norm of < 30 mg/Nm3

For this purpose, the project proponent has proposed installing ESP.

ESP considered is at 99.9%, which means the feed to ESP is < 30000 mg/Nm3

ESP alone will not be adequate.

Based on past operating experience, the project proponent should indicate what design changes have been opted for the new plant, including any operational modifications to ESP to reduce particulate emission.

For example, say the use of Ammonia to improve the conductivity of the dust etc.

 

Flue Gas Desulphurisation

No Mention made

There is no system adopted to meet the norm. This should be explained in the Draft EIA.

A temperature of intake and returned water

There is no mention of the same.

The project proponent must state both the design temperature of seawater intake and condenser return water temperature.

Desalination plant

Seawater requirement for desalination plant stated is 14976 m3/day and wastewater generation as 7788 m3/day, which means a permeate recovery of 47.99%.

The sweet water demand of 7200 m3/day.

There is no such recovery possible as the best world average is 29% recovery. The data is not reliable.

It is not clear from where demand the sweet water demand will be met.

 

fly ash management

3290 TPD Ash (Fly ash of 2566 TPD & bottom ash of 724 TPD).

 

By utilising (70:30 Indian coal & imported coal) about 2503 TPD Ash is generated from the proposed plant (i.e: Fly ash (1952 TPD) & bottom ash (551 TPD)).

The fly ash management must be based on worst case scenario of 100% domestic coal usage as stated in the first scenario.

The scenario should not take into account blended coal.

 Questions posted here are

The quantity is so huge in terms of the tonne per day - how can fly ash of 2566 TPD used in Cement plant and bottom ash of 724 TPD be utilized or stored in ash pond?

Details unavailable.

What kinds of Silo provisions have been made for storage of both fly ash & bottom ash?

Existing Ash pond

Not mentioned

The position of the existing accumulated ash of the old TPP is not clear.

What is the position of the existing ash? Has it been disposed?

Environmental Management Plan

The project cost is Rs 4800 Crores. Environmental Management Plan of a total indicated as Rs 478 Crores of capital. This equals 9.95% of project cost.

In addition, Rs.48 Crores is given as recurring expenditure apart from CSR provision

Environmental mitigation cost break-up is not provided.  It is not sure if it will be adequate for protecting the environment, taking into account the stringent PM, SO2, and other norms.

 

Disposal of Sea Water

Disposal of wastewater to sea is mention

There is no indication about outfall design and pumping system for Ocean disposal of RO reject & cooling water return.

Executive Summary of ETPS

Published in the New Indian Express and DT Next