Thermal Power Plants Should Comply with New Emission Norms in Post COVID-19 World

A difficult and different year that upended lives and economies is behind us and the new year is all about revival. While the world was busy combating an unprecedented pandemic, several other ongoing issues, for instance rising carbon emissions, had to be given equal attention. With every industry that suffered a setback in some form or the other, looking to revive itself in a post pandemic world, the need for adhering to emissions is now urgent, more than ever before. In case of thermal power plants in India, there are several strategic priorities and technologies that need to be implemented, as we move ahead into the post COVID-19 era.

The Coal Imperative and Making Peace with It

For starters, alongside policy pronouncements to shift to cleaner fuels which has delivered astounding results in the past decade for both solar and wind plants and has resulted in them occupying a centre stage, base load power demand in India being such that coal-fired thermal power plants still account for over 70% of India’s electricity. So, we can expect thermal power to continue to occupy the top slot for quite some time to come, and we need to make strategies to mitigate risk of carbon emissions, pollution, and climate change by adopting technologies that lower coal consumption on one end and reduce emissions on another.

Adoption and The Science Behind NOx Reduction Technology

Let’s begin with understanding the ways in which NOx reduction technology can be adopted. There are two solutions, any of which can help keep emission within 300 mg / Nm3. First is staged combustion, which is used in most application. This method supplies only a part of the air required by stoichiometry in the burner area and the remaining 20-40 per cent via the over fire air (OFA) system. The second is using low-NOx burners, which, in their new or modified form offer several additional advantages (besides NOx reduction). These include flame stability, fast ignition, good flame shape and wide turn-down ratio. Furthermore, NOx-reduction measures allow you to tailor them depending on the boiler dimensions, auxiliary equipment, fuel quality and other conditions at the power plant. Reducing them can also improve efficiency of coal plants. Implementing these solutions on site, however, can take up to one year.

Consequently, achieving less than 300 mg/ Nm3 should not be an issue. There is a general misconception that just changing some components in the furnace will help reduce NOx. While alteration or replacement of boiler burner may lead to 10-15 per cent reduction in NOx emissions, more changes must be done in terms of air flow staging to reduce NOx near burners.

Further reduction must be done by adopting flue-gas treatment technologies such as selective non-catalytic reactors (SNCR) or selective catalytic reactors (SCR). However, these are expensive compared to the modern primary NOx reduction technologies. Europe an coal-based power plants have been meeting stricter NOx limits than Indian coal-based power stations. While existing coal-based thermal power units in Europe have limits to emit no more than 165mg / Nm3, those in India can emit up to 450 mg/Nm3.

As industry players are willing to provide technical support to effectively operate the system there is hope for thermal powers in India running uninterrupted and realising their true potential in the country’s energy generation capacity. By using state-of-the-art primary NOx reduction technology the level of NOx emissions that can be achieved and have been achieved also in India by burning Indian coals is even less than 200mg/Nm3 and anyhow well below 300mg/Nm3.

So, what makes NOx reduction technology an ideal choice to ensure sustainable functioning of thermal power plants. Elevated levels of NOx affect a person’s respiratory tracts. Besides being harmful to everyone in general, it puts the vulnerable lot, those with respiratory infections and asthma at further risk than they already are. The chances of chronic lung diseases are much higher with this kind of exposure. Such gases can reduce the lungs’ defence against bacteria, making them more susceptible to infections. Also, sunlight triggers photochemical reaction in such gases that can cause the formation of ground-level ozone and secondary particulate matter formation.

Way Forward

Coal-powered thermal plants account for around 72 per cent of the country’s power generation. Even NITI Aayog, the government think tank, has estimated that coal’s share in the overall energy mix will be around 44 per cent in 2040. As the second largest producer of coal globally, India has the 4th largest reserves of coal in the world. Though efforts are being made in the right direction to increase power generation from renewable energy sources, India would still be dependent on coal in foreseeable future. Quicky regulatory decisions and adoption advanced technology solutions, are the two key elements for ensuring environment-friendly and uninterrupted functioning of thermal power plants in India.

- Sanjay Agarwal, Managing Director, Fortum India