Flue Gas Desulfurization: Industry and Market Overview

This blog post is the first in a three-part series that discusses flue gas desulfurization (FGD). This post provides overviews of sulfur dioxide pollution (SO₂) and emissions regulations, the FGD industry, and global FGD market trends. The second post provides high-level overviews of wet, semi-dry, and dry FGD technologies with respect to SO₂ capture applications at coal-fired power plants. The final post explores representative FGD process flows and chemistry for each of the three FGD technology types as applied to coal-fired power plant applications.

Sulfur dioxide (SO₂) is formed primarily through the combustion of sulfur-containing fossil fuels, such as coal and oil, by the power generation sector and other industrial facilities.¹ Because processed natural gas typically contains only trace amounts of sulfur, natural gas combustion is generally not a significant source of SO₂ emissions.² FGD is a suite of technologies developed over the years to reduce SO₂ emissions by capturing SO₂ from point sources of flue gas such as coal-fired power plants.

SO₂ has many harmful health and environmental effects including:^3,4,5

• Irritation of the eyes and mucous membranes;
• Irritation of the respiratory system (coughing, bronchitis);
• Worsening of existing respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD);
• Reaction with atmospheric moisture to form sulfuric acid, resulting in acid rain, which causes acidification of surface waters, corrosion and damage of buildings, and soil degradation; and
• Formation of particulate matter pollution that results in haze, reduces visibility, and may penetrate deeply into the lungs and contribute to health problems.

Given the harmful health and environmental effects of SO₂ in the atmosphere, many governments around the world have enacted regulations aimed at significantly reducing SO₂ emissions. These regulations are typically attained using FGD.

In “Global Sulfur Dioxide Emissions and the Driving Forces,” Zhong et al. write that developed countries have made significant progress in mitigating SO₂ pollution through decades of effort, while most developing countries have only recently started to adopt effective SO₂ control strategies. Zhong et al. state that China only began to impose SO₂ regulations in 2000 and that China’s pace of emission reduction accelerated following the issuance of the Air and Pollution Prevention and Control Action Plan in 2013, while India and other countries have seen continuing increases in SO₂ emissions because of the growth of electricity demand and the absence of effective emissions control regulations.⁶

In the United States, the Environmental Protection Agency (EPA) has set national ambient air quality standards for six criteria pollutants, including SO₂, under the Clean Air Act (CAA),⁷ and the CAA’s “Good Neighbor” provision addresses cross-state air pollution of emissions including SO₂.⁸ The EPA’s Acid Rain Program (ARP) caps the amount of SO₂ emissions by power plants at approximately one-half of the 1980 SO₂ emissions from the power plant sector.⁹ Further, SO₂ is also controlled under the EPA’s Regional Haze Rule,¹⁰ and the Mercury and Air Toxics Standards (MATS) led to additional decreases in SO₂ emissions.¹¹

As will be discussed in detail in subsequent blog posts of this series, FGD technologies generally fall into one of three categories:¹²

• Wet FGD systems utilize a scrubber, or spray tower, to contact an aqueous slurry of alkaline sorbent (typically calcium-based reagents such as limestone or lime) with the flue gas to absorb acid gases including SO₂.
• Semi-Dry FGD systems utilize a spray dryer to contact the flue gas with an aqueous slurry (typically calcium- and sodium-based reagents), similar to wet FGD systems, but the slurry has a higher sorbent concentration and finer spray droplets than wet systems.
• Dry FGD systems inject powdered sorbent, typically calcium- and sodium-based alkaline reagents, directly into the furnace, the economizer, or downstream ductwork of power plants to absorb SO₂ and other acid gases.

Importantly, with respect to the global construction industry, the deployment of FGD systems (particularly wet FGD systems) typically results in large capital projects. Installation of wet and semi-dry FGD systems typically entails equipping new SO₂ point sources or retrofitting existing SO₂ point sources with large reaction vessels (scrubbers and spray dryers) as well as associated large-scale ducting, fans, piping, pumps, reagent storage and delivery systems, and/or de-watering equipment.

Several market analysis reports indicate growth in the global FGD market over the next decade:

• Markets and Markets (MnM) states that the global FGD market was valued at USD 19.3 billion in 2021 and is projected to reach USD 24.9 billion by 2026 (5.2% compound annual growth rate, CAGR). MnM writes that the wet FGD segment accounted for the largest market share in 2020, and that market drivers include stringent SO₂ emissions standards and an increased number of coal-fired power plants in China and India.¹³
• Inkwood Research states that the global FGD market is expected to reach USD 36.1 billion by 2032, growing at a CAGR of 4.9% between 2023 and 2032. Inkwood Research indicates that dry FGD systems are the fastest-growing technology in the market, power generation is the dominating application in the market, and Asia-Pacific (China, India, and others) is the fastest-growing region in the market.¹⁴
• IMARC Group states that the global FGD market is expected to grow at a CAGR of 4.41% between 2024 and 2032. IMARC Group also indicates that wet FGD systems, power generation, and the Asia-Pacific region account for the largest market shares of system type, application, and geographical region, respectively.¹⁵
• Research Nester indicates it expects the global FGD market to grow at a CAGR of over ~8% from 2024 to 2036, with revenue up from ~USD 10 billion in 2023 to an expected USD 20 billion in 2036 due to expected increase in demand for electricity. Research Nester expects dry FGD systems and the Asia-Pacific region to generate the highest market shares.¹⁶
• Straits Research indicates that the global FGD market was valued at USD 20.81 billion in 2022 and is estimated to reach USD 29.36 billion by 2031, a CAGR of 3.9%. Straits Research writes that wet FGD systems, power plant applications, and the Asia-Pacific region dominate the market.¹⁷

¹     “Sulfur Dioxide Basics,” U.S. Environmental Protection Agency (U.S. EPA), accessed July 17, 2024. https://www.epa.gov/so2-pollution/sulfur-dioxide-basics.

²     Jonathan DeVilbiss and Suparna Ray, “Sulfur dioxide emissions from U.S. power plants have fallen faster than coal generation,” U.S. Energy Information Administration, February 3, 2017. https://www.eia.gov/todayinenergy/detail.php?id=29812.

³     U.S. EPA, “Sulfur Dioxide Basics.”

⁴     “Sulfur dioxide (SO2): sources and health impacts,” Meersens, accessed July 17, 2024. https://meersens.com/sulfur-dioxide-so2-sources-and-health-impacts/?lang=en.

⁵     “Global Flue Gas Desulfurization Market Forecast 2023–2032,” Inkwood Research, accessed July 17, 2024. https://www.inkwoodresearch.com/reports/flue-gas-desulfurization-market/.

⁶     Qirui Zhong, et. al., “Global Sulfur Dioxide Emissions and the Driving Forces,” June 29, 2020, p. 3, Retrieved on July 18, 2024. https://discovery.ucl.ac.uk/id/eprint/10102375/3/Meng_Global%20Sulfur%20Dioxide%20Emissions%20and%20the%20Driving%20Forces_AAM.pdf.

⁷     “Clean Air Act Requirements and History,” U.S. Environmental Protection Agency (EPA), retrieved July 18, 2024. https://www.epa.gov/clean-air-act-overview/clean-air-act-requirements-and-history.

⁸     “Cross-State Air Pollution,” U.S. Environmental Protection Agency (EPA), retrieved July 18, 2024. https://www.epa.gov/Cross-State-Air-Pollution/cross-state-air-pollution.

⁹     “Acid Rain Program,” U.S. Environmental Protection Agency (EPA), retrieved July 18, 2024. https://www.epa.gov/acidrain/acid-rain-program.

¹⁰     “Fact Sheet: Final Amendments to the Regional Haze Rule and Guidelines for Best Available Retrofit Technology (BART) Determinations,” U.S. Environmental Protection Agency (EPA), June 15, 2005. Retrieved July 18, 2024. https://www.epa.gov/sites/default/files/2016-02/documents/fs_2005_6_15.pdf.

¹¹     “Mercury and Air Toxics Standards,” U.S. Environmental Protection Agency (EPA), retrieved July 18, 2024. https://www.epa.gov/stationary-sources-air-pollution/mercury-and-air-toxics-standards.

¹²     “Air Pollution Control Technology Fact Sheet: FGD – Wet, Spray Dry, and Dry Scrubbers,” U.S. Environmental Protection Agency (EPA), EPA-452/F-03-034, 2003. Retrieved June 10, 2024. https://www3.epa.gov/ttncatc1/dir1/ffdg.pdf.

¹³     “Flue Gas Desulfurization System Market,” Markets and Markets, December 2021. Retrieved on July 18, 2024. https://www.marketsandmarkets.com/Market-Reports/flue-gas-desulfurization-systems-market-862.html.

¹⁴     “Global Flue Gas Desulfurization Market Forecast 2023-2032.” Inkwood Research. Retrieved July 18, 2024. https://www.inkwoodresearch.com/reports/flue-gas-desulfurization-market/.

¹⁵     “Flue Gas Desulfurization Market Report by Product Type (Wet FGD Systems, Dry and Semi-Dry FGD Systems), End Use (Power Generation, Cement, Chemical, Iron and Steel, and Others), and Region 2024-2032,” IMARC Group, retrieved July 18, 2024. https://www.imarcgroup.com/flue-gas-desulfurization-market.

¹⁶     “Flue Gas Desulfurization System Market revenue to surpass USD 20 Billion by 2036, says Research Nester,” GlobeNewswire, March 20, 2024. Retrieved July 18, 2024. https://www.globenewswire.com/news-release/2024/03/20/2849278/0/en/Flue-Gas-Desulfurization-System-Market-revenue-to-surpass-USD-20-Billion-by-2036-says-Research-Nester.html.

¹⁷     “Flue Gas Desulfurization System Market,” Straits Research, retrieved July 18, 2024. https://straitsresearch.com/report/flue-gas-desulfurization-system-market.

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