CRH

Improving air quality requires improving emission control methods in coal power plants employing emerging technologies.

Despite growing electricity demand and ensuing industrialization, coal may remain a significant power source worldwide, making shifting to carbon-neutral fuels challenging. The consumption of coal also leads to severe air pollution and health concerns. Plant owners and managers must improve air quality in coal power plants by improving emission control technologies. There is evidence that conventional air pollution control methods can remove pollutants individually, and few studies examine the possibility of controlling multiple pollutants simultaneously using the latest technologies. Burning coal annually emits 15 billion tonnes of carbon dioxide, contributing 27 percent of the global primary energy supply.

Air pollution causes respiratory diseases and lung diseases. Humans have been affected by mercury-related neurological damage, and other animals have faced developmental problems due to mercury exposure. Greenhouse gases such as CO2 contribute to global warming. As part of its report, the Intergovernmental Panel on Climate Change (IPCC) recommended limiting global warming to 1.5 degrees Celsius. The Paris Climate Agreement, 2015 also emphasized the need to achieve carbon neutrality and net-zero emissions worldwide by 2050. According to the Emissions Gap Report, updated nationally determined contributions and mitigation pledges under the Paris agreement only reduced 7.5 percent of projected 2030 greenhouse gas emissions. Global warming could reach 2.7°C by the end of this century if national policies are not in place.

The following technologies can manage air pollution arising due to coal-powered plants.

Flue gas desulfurization (FGD): Coal's sulfur content and the efficiency of its treatment technology determine how much it emits SO2. FGD removes pollutant pollutants from flue gases using sorbents. FGD technologies can be wet or dry. Flue gas passes through an absorber saturated with moisture, resulting in slurry and wet byproducts in a wet FGD (WFGD). There is no saturation of flue gas in dry FGD (DFGD) because the waste is dry. Most of the time, this technique is effective for coal containing a low to medium sulfur content, but it can also be important for coal containing a high sulfur content. As part of the sorbent injection method, sorbents are usually injected upstream of flue gas in powder or slurry form. Precipitation of pollutants from coal combustion is more effective using limestone in the fluidized bed (FB) method.

Carbon removal and storage technologies: An effective post-combustion method involves the removal of CO2 by adsorption. Plant owners can leverage the adsorption characteristics of the post-combustion method. Adsorbent characteristics include surface area, pore size, solubility, functional groups, molecular weight and size, and operating conditions, such as temperature and pressure, which determine the removal efficiency of any gaseous pollutant. It is important to understand these individual factors' impact on adsorption behavior, as several factors can impact the adsorption process.

Energy-efficient process technologies: Commercial-scale power generation relies heavily on pulverized coal combustion (PC). In the technology industry, improvements have primarily focused on improving plant thermal efficiency by increasing steam pressure and temperature. A circulating fluidized-bed (CFB) boiler burns low-grade coal or coal that is difficult to burn in a PC boiler by CFB.

Most countries plan to phase out coal power plants and switch to other renewable sources such as hydroelectric, water, solar, and wind. Global governments prioritize reducing greenhouse gas emissions and improving air quality by reducing coal's electricity and energy production share. A phase-out of coal can limit the construction of new coal mines, power plants, and associated infrastructure while encouraging the use of other renewable energy sources.

A low input cost of renewable resources might be one of the reasons many countries are moving away from coal. Due to policy changes, coal-fired power plants may become non-performing assets and a liability in the future.