New Report Flags Sulphur Dioxide Emissions From Bokaro Steel Plant

Decarbonising the steel industry — one of the largest coal consuming industries in India — focuses primarily on reducing carbon dioxide emissions to prevent the greenhouse gas effect. However, industrial processes in steel-making also cause air pollution, releasing sulphur dioxide, nitrogen oxides, and particulate matter, all of which adversely impact public health.

A new analysis by the Centre for Research on Energy and Clean Air (CREA) tracked air pollution emissions disclosures from the Bokaro Steel Plant (BSL) in Jharkhand. It found that even though BSL met existing regulatory limits, pollution from the plant led to around 273 low birthweight births, and 284 preterm births each year.

India’s installed crude steel capacity is projected to reach between 260 million and 280 million metric tons by 2035, keeping up pace with growing demand from the automotive, renewables, and defence sectors. It currently accounts for 10-12% of India’s carbon emissions, making it a key sector for decarbonisation on the way to net-zero emissions. The use of blast furnaces and basic oxygen furnaces in additional steel capacity could lock in a carbon-intensive process.

Until innovations on how to replace coal in steel-making become viable, investing in better air monitoring and filtration could help reduce the impacts of air pollution caused by the same process, the CREA report suggests.

“The emissions by the industry are self-reported or reported by a third party hired by the industry. The reported emissions for compliance are always below the standard, whether it is BSL, Bhillai Steel Plant, IISCO [Indian Iron and Steel Company] Plant, or Durgapur Steel Plant. Data discrepancies and inconsistencies undermine the steel sector’s impact on air pollution,” said Anubha Aggarwal, an analyst at CREA and the lead author of the report.

Sulphur dioxide from sintering

BSL was chosen because it’s one of India’s oldest steel plants, operated by the Steel Authority of India Limited, India’s largest government-owned steel maker, accounting for 13% of the country’s crude steel capacity. BSL is set to expand its capacity from 5.25 million tonnes per annum to 7.5 million tonnes per annum. “This expansion is expected to substantially increase the plantʼs fuel consumption and emissions, making an assessment of its current environmental performance timely and policy-relevant,” says the study.

Data for emissions were taken from the plant’s six monthly compliance reports, and covered the plant’s sinter plant, coke oven, refractory material plant, blast furnace, and steel melting shop. In total, the plant emitted 34,700 tonnes of particulate matter (PM), 19,600 tonnes of nitrogen oxides (NOX), and 47,700 tonnes of sulphur dioxide (SO2).

The sinter plant, where heat is used to fuse together fine particles of iron ore and other elements like limestone, was the most polluting process, accounting for 49% of PM, 40% of SO2, and 52% of NOX emissions.

These emissions were within government-prescribed limits for integrated steel and iron plants, which were issued in 2012 and have been revised periodically. The norms prescribe limits for each component of the plant, such as the coke oven, steel melting shop, and blast furnace.  While sintering plants are prescribed limits of up to 150 micrograms per metre cubed for PM2.5, there are no sulphur dioxide limits for them.

“Sulphur dioxide is a precursor of PM2.5 and secondary particulate matter contributes 50% to overall PM2.5 levels in India,” said Aggarwal. “The Commission for Air Quality Management in its report, stated that secondary particulate matter formed from key precursor gases such as sulphur dioxide, oxides of nitrogen, ammonia, and Volatile Organic Compounds (VOCs), accounts for 27% of Delhi’s air pollution problem,” she added.

CREA simulated the extent to which pollutants from the plants disperse across the region using the CALPUFF model, which has been evaluated and adopted by the U.S. Environmental Protection Agency. As per the model, emissions from the plant reach as far as Ranchi and Dhanbad, major cities in Jharkhand.

Mongabay-India wrote to the head of the Bokaro Steel Plant requesting comment on CREA’s report, but did not receive a response at the time of publishing.

Continuous monitoring for better compliance

One possible solution to improving air pollution emissions is replacing the technology in the plant’s stacks. Currently, of the six ducts for sinter stacks in the BSL plant, four are operating with multi-cyclone dust collectors, an older technology that uses centrifugal force to collect coarse particles from gas streams. Electrostatic precipitators (ESPs) can efficiently remove particles from a gas stream by electrically charging them, but are installed in only two of BSL’s sinter ducts.

“Cyclones and Multicyclones dust collectors are primitive technology, and ESPs are very commonly used with a good supply chain. Public sector-operated steel plants in India are mostly using ESP technology, and private sector-operated large integrated steel plants use a combination of ESPs and bag filter technology,” said Jayanta Moitra, a senior consultant at EMTRC, an environmental consultancy, who was not involved with CREA’s report. “Trapping point source emissions is much easier than trapping the fugitive emissions from secondary sources in a steel plant. Fugitive emissions are not adequately controlled by most integrated steel plants in India at the moment,” he added. Fugitive emissions are unintended leaks of particles, vapours, and gasses from industrial plant processes.

The CREA report notes that emissions from the plant’s stacks are consistently reported as being well below recommended regulatory levels. All data reported is from manual monitoring. “Such uniform compliance raises questions about the credibility of the monitoring process — for example, given the variability within the small number of reported readings, it is possible or even likely that a complete set of continuously monitored hourly data would show periods of non-compliance,” says the report.

Continuous emission monitoring systems (CEMS) could make data more transparent and accessible, said CREA.

(Published under Creative Commons from Mongabay India)