Coal is good right arm of the Indian power sector for generating electricity. Out of total installed capacity of power stations, share of electricity generation from use of coal is close to 55%. From total coal consumption, approximately 65% is consumed by the power utilities and nearly 6% by the captive power units. Coal’s ability to supply power during peak power demand either as base power or as off-peak power is greatly valued. Coal is easy to burn and produces high energy upon combustion. Coal is the most abundant and geographically dispersed fossil fuel and therefore is a reliable energy source. Generating electricity using coal is relatively inexpensive. The initial investment costs for the construction of a coal power plant are high, but the subsequent operating costs are low. Power plant operators thus have an economic interest. Coal-fired plants are considered safer and certainly not likely to cause catastrophic events. Coal is still the favorite fuel for the electricity generation and its usage is continuously increasing to meet the energy demands of the country. National Electricity Plan has been revised to make room for more coal. It adds 94,000 MW of new coal-fired capacity in between 2018 to 2027.
Unwelcome Situation
Electricity is a clean form of energy at the point of consumption. Extensive use of coal as fuel for thermal power plants producing electricity has a striking impact over the climate and natural environment depending upon the various factors.
Many grades of coal are being used to produce power and are categorised on the basis of useful heat value (UHV). Coals are classified into three main ranks lignite, bituminous coal, and anthracite based on the amount of carbon, oxygen and hydrogen present in the coal. Other constituents include hydrogen, oxygen, nitrogen, ash and sulfur. Capacity of coal to give energy depends upon the percentage or carbon content. Indian coal has high ash content which leads to technical difficulties in utilising the coal. Some specific problems with the high ash content include high ash disposal requirements, corrosion of boiler walls and fouling of economisers, and high fly ash emissions. Indian coal is mostly of sub-bituminous followed by bituminous rank and lignite. Coal power plants bring jobs and prosperity to their surrounding regions but at the same time are the main contributors for atmospheric pollution and greenhouse gases.
Coal combustion in power plants is a complex phenomenon. Formation of the heat and other byproducts like pollutant gases go through many complex non-linear processes. The anthropogenic pollutants emitted to the atmosphere from these coal using power plants depend largely upon the characteristics of the coal burned, temperature of the furnace, actual air used and any additional devices to control the emissions. Emissions that come from these plants could be categorised as gaseous emissions, particulate emissions and trace elements.
Gaseous Emissions
Five major gaseous forms of nitrogen compounds are released as a result of burning coal for electricity production. These include nitrogen gas (N2), ammonia (NH3), nitrous oxide (N2O), nitric oxide (NO), and nitrogen dioxide (NO2). Nitric oxide (NO) and nitrogen dioxide (NO2) collectively known as NOx. Nitrogen oxides are contributors to acid deposition caused by the oxidation reaction of NO to nitric acid. The epidemiological studies provide evidence that long-term NO2 exposure may decrease lung function and increase the risk of respiratory symptoms and cause relaxation of smooth muscle cells, increase pulse rate and effect the systolic blood pressure, acute circulatory collapse and fainting are also possible. Dilation of vessels in the retina leads to vision disorders. The organic nitrate, peroxyacetyl nitrate (PAN), is often present in highly polluted areas because of the reaction between the peroxyacetyl radical and nitrogen dioxide which in cohesion with photochemical smog irritates the mucous membranes, eyes and skin.
The combustion of coal is the primary source of sulfur pollutants. The sulfur in the coal is oxidised to form sulfur dioxide gas when the coal is burned. Hydrogen sulfide (H2S) is emitted from each coal-to-electricity system. Inhaling can damage the respiratory system and are irritants.
Combustion of coal at thermal power plants emits mainly carbon dioxide (CO2) which is produced from the burning of carbonaceous materials. CO2 is the most publicised of the greenhouse gases due to its increasing rate of production and atmospheric concentration. Atmospheric concentrations of carbon dioxide have been steadily rising. Excess carbon in the atmosphere warms the planet and makes the ocean water more acidic, putting marine life in danger.
Carbon monoxide (CO) results from the incomplete combustion of hydrocarbons. This odourless, colourless, tasteless and flammable gas directly influences the concentrations of other greenhouse gases in the atmosphere by removing hydroxyl radicals. Its higher concentrations can produce toxic symptoms including headache, mental dullness, dizziness, weakness, nausea, vomiting and loss of muscular control. Methane, the simplest hydrocarbon has an estimated global warming potential of 21 times that of carbon dioxide. It is also a contributor to photochemical smog.
Particulate Emissions
Coal-fired power plants are a major source of fine particulate matter (PM) the ultrafine dust. The chemical composition of PM varies with coal type, power plant design and location, and also with ambient conditions such as temperature and wind direction. PM is usually classified by particle size because of the wide variation and complexity of its chemical composition. National emission standard limit is PM2.5 which means fine particles less than 2.5 mm in diameter. Primary PM2.5 particles are those that are emitted directly to the air from coal-fired power plants. Secondary PM2.5 is formed from reactions with gaseous pollutants, such as SOx, NOx, NH3 and volatile organic compounds (VOCs) through nucleation, condensation, coagulation and evaporation of water droplets in which the gases are dissolved and reacted. PM is known to contain a number of harmful chemicals such as antimony, arsenic, beryllium, cadmium, chromium, cobalt, lead, manganese, mercury, nickel, selenium and polycyclic organic matter (POM). High concentrations of PM2.5 significantly affect the health of citizens and its long-term exposure augments cardiovascular and respiratory illnesses.
Trace Elements
Trace elements (TEs) are of great concern as the emissions are higher in coal-based power plants. TEs are defined as elements that exist at concentrations of <100 ppm. TEs are emitted in both the gas phase as well as in solid form referred to as coal fly ash. Coal ash typically contains heavy metals. Coal is found to emit the highest amount of 6 priority hazardous air pollutants (HAPs) which are also TEs compounds [i.e. arsenic (As), chromium (Cr), mercury (Hg), nickel (Ni), hydrogen chloride (HCl), hydrogen fluoride (HF)]. TEs are hazardous, depending on the concentration. If eaten, drunk or inhaled, these toxicants can cause nervous system impacts such as cognitive deficits, developmental delays and behavioural problems.
Sequel
Coal power generation is a primary cause of greenhouse gas (GHG) and toxic airborne emissions and is a major contributor to local air pollution. The economic cost of the health impacts from outdoor air pollution is estimated to be 3% of India’s GDP. As coal use expands, the impacts on public health and broader environmental issues are set to worsen. Coal power plants in India are most lethal in the world. Therefore, understanding the environmental implications of producing electricity from coal is an important component of any plan to reduce total emissions and resource consumption. Further on 2-10-2016 India has ratified the Paris Agreement on climate change which require curbing carbon dioxide (CO2) emissions to keep global average temperatures from rising above 1.5°C. Achieving this goal will not be possible without a rapid phase-out of existing coal-fired electricity and a dramatic reduction in the construction of new coal power.
Solution Strategy
India is looking to alter the generation mix in the years to come, focusing on a low carbon growth strategy. Renewables have become synonymous with climate change mitigation and India is successfully adopting these sources of energy. In the past four years, there has been a clear shift towards renewables, especially solar energy.
India’s push for solar energy began in 2010 when the Government announced the Jawaharlal Nehru National Solar Mission (Jnnsm) under National Action Plan on Climate Change (Napcc). Phase I focused on capturing the “low-hanging” options in solar thermal, promoting off-grid systems and modest capacity addition in grid-based systems, Phase II intended to achieve aggressive capacity addition. The mission has a target of 20 GW installed solar capacity by 2022. In 2015, the Government of India revised its target for Jnnsm to 100 GW by 2022.
The Government is promoting solar energy through fiscal and promotional incentives such as capital and interest subsidies, generation-based incentives, viability gap funding (VGF), financing solar rooftop systems as part of home loans, preferential tariff for power generation from renewable sources, foreign direct investment (FDI) up to 100 per cent and a Modified Special Incentive Package Scheme (M-SIPS) of the Ministry of Electronics and Information Technology (MEIT). The Ministry of Power (MoP) has issued the renewable purchase obligation (RPO) trajectory up to 2019. Green energy corridors (GEC) with dedicated transmission system are being created for power from renewable energy projects. A World Bank loan financing arrangement of $100 million is being worked out for creating internal infrastructure of solar parks. International solar alliance was approved by the Cabinet in December 2016. Solar Parks and Ultra Mega Solar Power Projects will be set up by 2019–2020 with the Central Government’s financial support. The total capacity, when operational, will generate 64 billion units of electricity per year that will lead to an abatement of around 55 million tonnes of CO2 per year over its life cycle. The World Bank, KFW, Asian Development Bank (ADB) and New Development Bank (NDB) have sanctioned $1300 million for State Bank of India (SBI), Punjab National Bank (PNB), Canara Bank to fund solar rooftops at less than 10% interest.
Rechristened Ministry of New and Renewable Energy has to ensure increase in the share of clean power: renewable (bio, wind, hydro, solar, geothermal and tidal) electricity to supplement fossil fuel based electricity generation and develop new renewable energy technologies, processes, materials, components, sub-systems, products and services at par with international specifications, standards and performance parameters. Its Green Campus Program aims to reduce fossil fuel-based consumption in next five years by 25% through renewable energy applications and energy efficiency measures.
India has joined the International Energy Agency (IEA) as an association country. IEA Clean Coal Centre provides information and assessments on all aspects of coal including end-use technologies to environmental issues.
The Indian national ambient air quality standards have been implemented by the Central Pollution Control Board (CPCB), a division of the Ministry of Environment and Forests.
Indian power plants are looking at converting their conventional particle emission control devices (PECD) such as electrostatic precipitators (ESP) into and fabric filters (FF). 99% of dust particles and other substances are absorbed while passing through the ESP. FF are dust filters which can effectively remove unintentional PM and are sensitive to removal of acid gases.
India, despite the adoption of alternative energy sources and energy efficient systems to reduce the rate of CO2 emissions, is now ready for large-scale carbon capture, utilisation and storage (CCUS) which encompasses methods and technologies that captures carbon dioxide emissions from coal-fired power plants and reuses or stores it, thus preventing CO2 from entering the atmosphere. CCUS technologies have the potential to secure up to 90% of CO2 emissions.
Closing
Reducing the negative health effects of coal power generation is on priority. India is on track to catalyse new investment in renewable energy infrastructure. It is significant to update the regulatory framework for enforcing power plant emission standards, including substantial automatic fines for every violation of emission limits. The world is walking away from coal. India needs a time-bound action plan to move away from coal-fired generation. However, there may be challenges and requirements for achieving this major energy transition.
Carbon Capture and Storage (CCS) technology seeks to capture CO2 before it is released into the atmosphere and store it underground.
*Harsha Rajwanshi is the Assistant Professor of Law, Gujarat National Law University & Faculty Advisor to GUVNL-GNLU Research Fellowship on Energy Law and Policy.