Close monitoring of the technology’s performance is necessary to ensure compliance, says the Centre for Science and Environment
Aerial View of Dadri NTPC Power Station. Photo: Wikimedia GE Power, the largest energy technology company announced on September 26 that it will install its advanced low NOx Boiler Technology for the first time in India. The technology will be implemented in two units of 490 MW at NTPC Dadri power plant in Dadri, Uttar Pradesh. This technology can help reduce Oxides of nitrogen (NOx) generation by up to 40 per cent from current levels in these units, according to GE Power.
In December 2015, the Ministry of Environment, Forest and Climate Change (MoEF&CC) revised emission standards for coal power stations. The units commissioned between 2004 to 2016 are presently required to meet NOx emissions standard of 300 mg/Nm3 while those commissioned before 2003 are required to meet NOx standard of 600mg/Nm3.
Coal-fired boilers in India are required to adopt low NOx burners (LNBs), over fire air (OFA) dampers and combustion optimization solutions which limits the production of NOx within the combustion zone.
However, last month, Ministry of Power filed an affidavit requesting the Supreme Court to relax the NOx standard from 300mg/Nm3 to 400-450mg/Nm3 citing concerns related to sufficiency of these technologies to meet the current standards. According to power plant officials, plants will have to go for post combustion NOx control technologies such as selective non-catalytic reduction (SNCR) and selective catalytic reduction (SCR) in addition to primary control measures to comply with the present 300mg/Nm3 standard, said the affidavit. The suitability of SCR for NOx control in Indian context remains a concern, and as such NTPC is tasked with running pilots to test the same, it added.
But experts say that such concerns are unwarranted at this stage. Welcoming NTPC Dadri’s move to adopt low NOx boiler technology, Rohit Pathania, Programme Manager (Energy Unit), Centre for Science and Environment says that its performance post-commissioning should be closely monitored. “In India, almost all of the presently operational plants have to meet the NOx emission limit of 600 mg/Nm3 or 300 mg/Nm3. We have been told repeatedly by technology suppliers that primary control measures can be sufficient to meet the present norms. In fact, according to several technology suppliers, the latest advanced low NOx boiler technologies are sufficient to keep NOx emissions below the 300 mg/Nm3 limit. Hence, thorough monitoring of these low NOx boiler technologies is necessary,” he said.
In December 2017, the Central Pollution Control Board had issued section-5 notices under the Environment (Protection) Act, 1986 to power stations saying plants shall take immediate measures like installation of low NOx burners, providing over fire air (OFA) etc. and achieve progressive reduction.
The apex court has called all power stations to explain their lack of action in the next hearing on 11th October. They have held that the new technologies are costly.
Oxides of nitrogen (NOx) are major pollutants responsible for both smog and acid rain, formation of secondary particulate matter (PM) and ground level ozone. NOx emissions from thermal power plants were unregulated till recently and increased dramatically by over 97 per cent— between 1996 and 2010—with an average annual growth of about 5 per cent. It is estimated that the new norms will help reduce NOx emissions by almost 45 per cent by 2026–27 against a business as usual scenario where no pollution control technologies are used.
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