Investments	12 Months Ended
Dec. 31, 2022
Equity Method Investments and Joint Ventures [Abstract]
Investments	14. Investments Chem-Mod LLC - At December 31, 2022, we held a 46.5% controlling interest in Chem-Mod LLC. Chem‑Mod LLC possesses the exclusive marketing rights, in the U.S. and Canada, for technologies used to reduce emissions created during the combustion of coal. Prior to 2022, the refined coal production plants discussed below, as well as those owned by other unrelated parties, licensed and used Chem-Mod LLC’s proprietary technologies, The Chem-Mod™ Solution, in the production of refined coal. The Chem‑Mod™ Solution used a dual injection sorbent system to reduce mercury, sulfur dioxide and other emissions at coal-fired power plants. We believe that the application of The Chem-Mod™ Solution prior to 2022 qualified for refined coal tax credits under IRC Section 45 when used with refined coal production plants placed in service by December 31, of both 2011 and 2009. Chem-Mod LLC was marketing its technologies principally to coal-fired power plants owned by utility companies, including those utilities that were operating with the IRC Section 45 refined coal production plants in which we hold an investment. Chem-Mod LLC is determined to be a variable interest entity (which we refer to as a VIE). We are the manager (decision maker) of Chem‑Mod LLC and therefore consolidate its operations into our consolidated financial statements. At December 31, 2022, total assets and total liabilities of this VIE included in our consolidated balance sheet were $14.8 million and $1.1 million, respectively. At December 31, 2021, total assets and total liabilities of this VIE included in our consolidated balance sheet were $19.4 million and $1.1 million, respectively. For 2022, total revenues and expenses were $1.0 million and $5.7 million, respectively. For 2021, total revenues and expenses were $82.7 million and $14.5 million, respectively. We are under no obligation to fund Chem-Mod’s operations in the future. Chem-Mod International LLC - At December 31, 2022, we held a 31.5% noncontrolling ownership interest in Chem-Mod International LLC. Chem-Mod International LLC has the rights to market The Chem-Mod™ Solution in countries other than the U.S. and Canada. Such marketing activity has been limited to date. C-Quest Technology LLC and C-Quest Technologies International LLC (which we refer together as C-Quest) - At December 31, 2022, we held a noncontrolling 12% interest in C-Quest’s global entities. C‑Quest possesses rights, information and technology for the reduction of carbon dioxide emissions created by burning fossil fuels. Thus far, C‑Quest’s operations have been limited to laboratory testing. C-Quest is determined to be a VIE, but we do not consolidate this investment into our consolidated financial statements because we are not the primary beneficiary or decision maker. Clean Coal Investments - • We have investments in limited liability companies that own or have owned 35 refined coal production plants which produce refined coal using proprietary technologies owned by Chem-Mod LLC. We believe the production and sale of refined coal at these plants prior to 2022 was qualified to receive refined coal tax credits under IRC Section 45. The 14 plants placed in service prior to December 31, 2009 were eligible to receive tax credits through 2019 and the 21 plants placed in service prior to December 31, 2011 were eligible to receive tax credits through 2021. • As of December 31, 2022: o We have a noncontrolling interest in one plant, which is owned by a limited liability company (which we refer to as a LLC). We have determined that this LLC is a VIE, for which we are not the primary beneficiary and therefore do not consolidate it. At December 31, 2022, total assets and total liabilities of this VIE were $35.3 million and $35.3 million, respectively. For 2022, total revenues and expenses of this VIE were zero and $0.3 million, respectively. • We and our co-investors each funded our portion of the on-going operations of the limited liability companies in proportion to our investment ownership percentages. Other than our portion of the on-going operational and decommission funding, there are no additional amounts that we are committed to related to funding these investments. Other Investments - At December 31, 2022, we owned a noncontrolling, minority interest in one startup venture totaling $2.2 million, four venture capital funds totaling $3.4 million and five certified low-income housing developments with zero carrying value. The low-income housing developments and real estate entities have been determined to be VIEs, but are not required to be consolidated due to our lack of control over their respective operations. At December 31, 2022, total assets and total liabilities of these VIEs were approximately $4.6 million and $0.4 million, respectively.

Chem-Mod LLC - At December 31, 2022, we held a 46.5% controlling interest in Chem-Mod LLC. Chem‑Mod LLC possesses the exclusive marketing rights, in the U.S. and Canada, for technologies used to reduce emissions created during the combustion of coal. Prior to 2022, the refined coal production plants discussed below, as well as those owned by other unrelated parties, licensed and used

Chem-Mod LLC’s proprietary technologies, The Chem-Mod™ Solution, in the production of refined coal. The Chem‑Mod™ Solution used a dual injection sorbent system to reduce mercury, sulfur dioxide and other emissions at coal-fired power plants.

We believe that the application of The Chem-Mod™ Solution prior to 2022 qualified for refined coal tax credits under IRC Section 45 when used with refined coal production plants placed in service by December 31, of both 2011 and 2009. Chem-Mod LLC was marketing its technologies principally to coal-fired power plants owned by utility companies, including those utilities that were operating with the IRC Section 45 refined coal production plants in which we hold an investment.

Chem-Mod LLC is determined to be a variable interest entity (which we refer to as a VIE). We are the manager (decision maker) of Chem‑Mod LLC and therefore consolidate its operations into our consolidated financial statements. At December 31, 2022, total assets and total liabilities of this VIE included in our consolidated balance sheet were $14.8 million and $1.1 million, respectively. At December 31, 2021, total assets and total liabilities of this VIE included in our consolidated balance sheet were $19.4 million and $1.1 million, respectively. For 2022, total revenues and expenses were $1.0 million and $5.7 million, respectively. For 2021, total revenues and expenses were $82.7 million and $14.5 million, respectively. We are under no obligation to fund Chem-Mod’s operations in the future.

Chem-Mod International LLC - At December 31, 2022, we held a 31.5% noncontrolling ownership interest in Chem-Mod International LLC. Chem-Mod International LLC has the rights to market The Chem-Mod™ Solution in countries other than the U.S. and Canada. Such marketing activity has been limited to date.

C-Quest Technology LLC and C-Quest Technologies International LLC (which we refer together as C-Quest) - At December 31, 2022, we held a noncontrolling 12% interest in C-Quest’s global entities. C‑Quest possesses rights, information and technology for the reduction of carbon dioxide emissions created by burning fossil fuels. Thus far, C‑Quest’s operations have been limited to laboratory testing. C-Quest is determined to be a VIE, but we do not consolidate this investment into our consolidated financial statements because we are not the primary beneficiary or decision maker.

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We have investments in limited liability companies that own or have owned 35 refined coal production plants which produce refined coal using proprietary technologies owned by Chem-Mod LLC. We believe the production and sale of refined coal at these plants prior to 2022 was qualified to receive refined coal tax credits under IRC Section 45. The 14 plants placed in service prior to December 31, 2009 were eligible to receive tax credits through 2019 and the 21 plants placed in service prior to December 31, 2011 were eligible to receive tax credits through 2021.

We have a noncontrolling interest in one plant, which is owned by a limited liability company (which we refer to as a LLC). We have determined that this LLC is a VIE, for which we are not the primary beneficiary and therefore do not consolidate it. At December 31, 2022, total assets and total liabilities of this VIE were $35.3 million and $35.3 million, respectively. For 2022, total revenues and expenses of this VIE were zero and $0.3 million, respectively.

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We and our co-investors each funded our portion of the on-going operations of the limited liability companies in proportion to our investment ownership percentages. Other than our portion of the on-going operational and decommission funding, there are no additional amounts that we are committed to related to funding these investments.

Other Investments - At December 31, 2022, we owned a noncontrolling, minority interest in one startup venture totaling $2.2 million, four venture capital funds totaling $3.4 million and five certified low-income housing developments with zero carrying value. The low-income housing developments and real estate entities have been determined to be VIEs, but are not required to be consolidated due to our lack of control over their respective operations. At December 31, 2022, total assets and total liabilities of these VIEs were approximately $4.6 million and $0.4 million, respectively.