We provide environmental solutions to customers in coal-fired power generation, municipal water and other industries primarily through emissions and water purification control technologies of our subsidiaries and joint ventures. Our proprietary technologies and associated product offerings provide pollutant control solutions to enable coal-fired power generators, municipal water and industrials to meet applicable regulations.
As of December 31, 2018 and 2017, we held equity interests of 42.50% and 50.00% in Tinuum Group, LLC ("Tinuum Group") and Tinuum Services, LLC ("Tinuum Services"), respectively, and each of their operations significantly impacted our financial position and results of operations for the years ended December 31, 2018, 2017 and 2016. We account for Tinuum Group and Tinuum Services under the equity method of accounting.
We operate two segments: Refined Coal ("RC") and Power Generation and Industrials ("PGI") (f/k/a "Emissions Control" or "EC"). The segments are discussed in more detail later under this Item 1. Our products are currently used for the removal of mercury and other air pollutants and for the purification of water.