The Role of Lignite in India's Energy Security

In an interaction with Industry Outlook, Shri Prasanna Kumar Motupalli, Chairman and Managing Director, NLC India Limited shared his views on the key advantages of using lignite over other fossil fuels like coal and natural gas in India, how lignite contributes to reducing India's dependence on imported energy sources, and how it enhances the country's energy security and more.

Could you provide an overview of the current landscape of lignite production and usage in India? How significant is lignite in India's overall energy mix?

Lignite deposits in India are primarily located in the tertiary sediments in the Southern & Western parts of the peninsular shield, particularly in Tamil Nadu, Puducherry, Gujarat, Rajasthan, and Jammu & Kashmir. Lignite is also in minor quantities in Odisha, Kerala & West Bengal. The production of lignite is 44.990 MT in 2022-23. Tamil Nadu accounted for 49.97% of the production, followed by Gujarat at 27.37%, and Rajasthan at 22.67%.

Tamil Nadu accounts for about 82% of India’s lignite reserves of 40.9 billion tonnes. Tamil Nadu has lignite reserves of 33,309.53 million tonnes. At present, only a small percentage of the total lignite reserves have been exploited. There is considerable scope for their exploitation and use of lignite in thermal power stations subject to cost economics, particularly in Tamil Nadu, Rajasthan, and Gujarat, which have limitations in the transportation of coal.

In terms of dispatch of lignite, Tamil Nadu had the highest share of 24.166 MT or 51.61%, followed by Gujarat at 26.27%, and Rajasthan at 22.12%. Tamil Nadu’s lignite production stood at 23.635 MT in 2021-22, followed by 18.026 MT in 2020-21.

Most lignite is used in boilers to generate electricity. However, small amounts are used in agriculture, in industry, and even, as a jet, in jewelry. Lignite fly ash produced by the combustion of lignite in power plants may also be valuable as a soil amendment and fertilizer.

Lignite may also be used for the cultivation and distribution of biological control microbes that suppress plant pests. Reaction with quaternary amine forms a product called amine-treated lignite (ATL), which is used in drilling mud to reduce fluid loss during drilling.

In India, the total installed generation capacity (MW) is 6,620 MW. This accounts for 1.6 % of the total installed generation capacity. About 4000 MW of lignite-based power plants are in various planning and construction stages.

Given the current landscape, what are the key advantages of using lignite over other fossil fuels like coal and natural gas in India?

Lignite is generally used for the generation of electricity. Across the world, when you consider the worldwide statistics, around 75% of lignite produced is used for power production, and around 12-13% is used for gasification. This lignite is not only used in agriculture to improve the quality of the land but is also used as a gem in pieces of jewelry.

Lignite-based power plants are pit head plants and generally avoid the transportation cost of fuel. This makes the power generated from Lignite relatively cheaper. Lignite-based power plants generate electricity at a cost significantly below that of all coal and natural gas power plants nationwide. Even though the calorific value of Lignite is less, the landed cost of lignite is less compared in terms of other fossil fuels. Considering less transportation involved, the environmental impact caused is also less. Hence, Lignite has advantages over coal and natural gas in terms of cost & environmental impact.

Furthermore, the adoption of Circulating Fluidized Bed Combustion technology for lignite was possible due to its lower Calorific value. This helps in avoiding the generation of undesirable emissions like SOx & NOx from combustion. Lignite contributes a smaller percentage to the Indian fossil fuel portfolio, however, is being utilized in full terms for its advantages.

Lignite mines are mostly Open cast mines and the Overburden in the Neyveli Region contains Clay & Silica. This has been effectively utilized for M-Sand production and sale of Ball clay for other purposes. This provides an opportunity for Wealth from Waste. The presence of lignite is comparatively not far from load centers similar to the presence of coal & natural gas. This effectively addresses the cost associated with the transmission of Power or fuel as well. Being an open cast mine, the mine voids and the OB dump provide opportunities for the Pumped Storage Project as well.

How does lignite contribute to reducing India's dependence on imported energy sources, thereby enhancing the country's energy security?

India’s electricity demand is growing at a faster pace compared to the capacity addition in terms of power generation and mining. Last year this resulted in the import of coal from foreign countries, to avoid supply disruption of electricity. A major challenge in coal-based power generation is the logistics. Transportation of coal from the Mine end to the Thermal Power Plant boundary has been constrained due to Railway line congestion.

Even though India has abundant coal reserves and production facilities, such a situation has been encountered in the country. To mitigate this challenge developing pit-head power stations near the load centers in the country. This is not possible because the presence of coal is mostly in the Eastern belt and the Load center is in the Western and southern parts, mandating transportation as a requirement.

However, the Lignite deposit exploited in Neyveli is relatively close to load centers like Chennai, Coimbatore, and Bangalore supporting in terms of cost economics. This results in reduced landed cost of power and addresses India’s Energy Security requirement. In addition, to meet the upcoming requirement, gasification of lignite to produce Methanol has been contemplated. NLCIL is establishing a 0.4 MTPA Lignite to Methanol project at Neyveli, which will in a large manner address the sustainability challenge.

In the context of environmental concerns, what role can technological advancements play in improving efficiency and reducing the environmental impact of lignite-based power generation? Could you also share some initiatives undertaken by NLC to reduce environmental impact?

Elector static Precipitators (ESP) fundamentally play a major role in capturing the fly ash generated from thermal power stations and its efficiency has also been at its best. In addition, with current-day Flue Gas Desulphurization (FGD) unit and Selective Catalytic Reduction (SCR) unit being introduced to new plants or retrofitted to the existing plants provide the opportunity to reduce SOx and NOx emissions. Additionally, the advanced ultra-supercritical technology plants based on higher parameters increase the efficiency and reduce the fuel consumption, overall reducing the emission impact.

The adoption of CFBC technology has also largely impacted emission generation. All of the above, the greenhouse gas emissions and the Carbon dioxide generated from Thermal Power Stations pose the biggest environmental challenge in terms of Greenhouse emissions. This emission is responsible for global warming and there has been much fear towards the possible outcome. Technological development in Carbon Capture, Utilization, and Sequestration has to happen in the country.

Therefore, with this the emissions level will be comparatively lesser and the impact on the environment is also lesser. In addition to this, the lignite power generation, there is a technology called CFBC technology, Circulating fluidized bed combustion technology where the emission levels are much lesser than the conventional thermal power generation capacity. Hence, in our TPS-II expansion, we have adopted the CFBC technology where the emission levels are very low and the ash generated is also effectively utilized in many environmentally friendly activities. 

In addition to this going forward to control the carbon emissions, the important aspect is to develop technology for carbon capture and carbon sequestration. Hence, we have entered into an agreement with Annamalai University and are going to sign an MOU where a pilot project will be established for establishing the carbon capture and sequestration process, and with that the emissions will further be reduced.

The R&D being done in this area has to be boosted up and pilot plants established to scale up to commercial scale. Only this will help in making the thermal power generation a viable option in the near future. Proper utilization of the captured carbon dioxide is the key to the real-time success of this technology. Theoretically, many options are available, and making it a reality is very important.