Midwest Energy Emissions Corp v. Evergy Inc

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Midwest Energy Emissions Corp. (n/k/a Birchtech Corp.) (Delaware)
  • Defendant: Evergy, Inc., Evergy Metro, Inc., Evergy Missouri West, Inc., and Evergy Kansas Central, Inc. (Missouri, Delaware, Kansas)
  • Plaintiff’s Counsel: The Simon Law Firm, P.C.; Caldwell Cassady & Curry P.C.
• Case Identification: 4:25-cv-00050, W.D. Mo., 01/23/2025
• Venue Allegations: Plaintiff alleges venue is proper because Defendants reside in the district, have committed acts of infringement in the district, and maintain a regular and established place of business at one or more coal-fired power plants located within the district, including the Iatan, Hawthorn, and La Cygne Generating Stations.
• Core Dispute: Plaintiff alleges that Defendants’ operation of coal-fired power plants infringes six patents related to methods for removing mercury from combustion flue gas.
• Technical Context: The technology concerns methods for controlling mercury emissions from coal-fired power plants to comply with environmental regulations, a critical function for the energy generation sector.
• Key Procedural History: The complaint notes that in a prior case in the District of Delaware, a jury found on March 1, 2024, that two of the patents-in-suit (the '517 and '114 patents) were willfully infringed by a third-party producer of refined coal. The complaint also alleges that Plaintiff contacted Defendants regarding their patented technology on multiple occasions between August 2016 and February 2022.

Case Timeline

Date	Event
2004-08-30	Earliest Patent Priority Date ('114, '225, '517 Patents)
2016-08-02	Plaintiff alleges first contact with Defendants regarding patented processes
2018-11-01	Plaintiff alleges second contact with Defendants
2019-07-09	U.S. Patent No. 10,343,114 issues
2019-08-07	Plaintiff alleges third contact with Defendants, providing '114 Patent
2020-03-17	U.S. Patent No. 10,589,225 issues
2020-03-24	U.S. Patent No. 10,596,517 issues
2020-03-24	U.S. Patent No. 10,668,430 issues
2021-02-23	U.S. Patent No. 10,926,218 issues
2021-03-03	U.S. Patent No. 10,933,370 issues
2022-02-08	Plaintiff alleges fourth contact with Defendants, providing additional patents-in-suit
2024-03-01	Jury verdict in separate Delaware litigation finds '517 and '114 patents willfully infringed
2025-01-23	Complaint filed

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 10,343,114 - "Sorbents for the Oxidation and Removal of Mercury"

• Patent Identification: U.S. Patent No. 10,343,114, "Sorbents for the Oxidation and Removal of Mercury," issued July 9, 2019.

The Invention Explained

• Problem Addressed: The patent describes the problem of removing mercury pollutants from flue gas generated by fossil fuel combustion. It notes that existing carbon injection methods are often inefficient, requiring large quantities of expensive sorbent that is difficult to separate from ash for reuse and creates solid waste disposal issues (Compl. ¶45; ’114 Patent, col. 2:11-20).
• The Patented Solution: The invention is a method using a halogen/halide-promoted sorbent to improve mercury capture. A promoter (such as bromine) is introduced into the process, reacting with a base sorbent (such as activated carbon) to create a highly reactive surface. This "promoted sorbent" then efficiently oxidizes elemental mercury and captures it from the flue gas stream (’114 Patent, Abstract; col. 3:13-22). The method can involve adding the promoter to the coal upstream, introducing it into the combustion chamber, or reacting it with the sorbent "in-flight" before injection (’114 Patent, col. 3:36-52).
• Technical Importance: This approach was designed to provide a more economical and effective mercury removal technology by using highly reactive sorbents that require shorter contact times and can be regenerated and reused (’114 Patent, col. 3:23-28).

Key Claims at a Glance

The complaint asserts at least one of claims 1-30 and specifically analyzes independent claim 25 (Compl. ¶¶ 168, 170).

• Claim 25: A method of separating mercury from a mercury-containing gas, comprising the steps of:
  • combusting coal in a combustion chamber to provide the mercury-containing gas, wherein the coal comprises an added bromine-based component (Br2, HBr, or a bromide compound) upstream of the chamber, or the combustion chamber itself comprises an added bromine-based component;
  • injecting a sorbent material comprising activated carbon into the mercury-containing gas downstream of the combustion chamber;
  • contacting the mercury in the gas with the sorbent to form a mercury/sorbent composition; and
  • separating the mercury/sorbent composition from the gas to form a cleaned gas.

U.S. Patent No. 10,596,517 - "Sorbents for the Oxidation and Removal of Mercury"

• Patent Identification: U.S. Patent No. 10,596,517, "Sorbents for the Oxidation and Removal of Mercury," issued March 24, 2020.

The Invention Explained

• Problem Addressed: The '517 Patent addresses the same technical problem as the '114 Patent: the inefficient and costly removal of mercury from combustion flue gas using conventional sorbent technologies (’517 Patent, col. 2:11-20).
• The Patented Solution: The patent discloses a method for reducing mercury in flue gas by combusting coal that comprises a bromine-based additive. This process forms a mercury-containing gas, from which mercury is then collected using a sorbent comprising activated carbon that is added to the gas stream (’517 Patent, Abstract; col. 3:36-44). The core technical principle is consistent with that of the ’114 Patent.
• Technical Importance: The method aims to provide a more cost-effective mercury removal process that can be implemented in facilities like coal-fired power plants to meet regulatory standards (’517 Patent, col. 3:23-28).

Key Claims at a Glance

The complaint asserts at least one of claims 1-30 and specifically analyzes independent claim 1 (Compl. ¶¶ 189, 191).

• Claim 1: A method for reducing mercury in a mercury-containing gas, comprising the steps of:
  • combusting coal in a combustion chamber, where the coal comprises an additive that includes Br2, HBr, a bromide compound, or a combination thereof, to form the mercury-containing gas; and
  • collecting mercury in the mercury-containing gas with a sorbent comprising activated carbon that is added to the gas.

U.S. Patent No. 10,589,225 - "Sorbents for the Oxidation and Removal of Mercury"

• Patent Identification: U.S. Patent No. 10,589,225, "Sorbents for the Oxidation and Removal of Mercury," issued March 17, 2020.
• Technology Synopsis: This patent discloses a method for treating mercury-containing gas by combusting a specific mixture comprising coal, pyrolysis char, and a bromine-based additive (HBr or a bromide compound). After combustion, a particulate sorbent comprising activated carbon is added to the resulting gas to capture mercury (’225 Patent, col. 23:66-col. 24:2).
• Asserted Claims: The complaint asserts at least one of claims 1-29, focusing on independent claim 1 (Compl. ¶¶ 206, 208).
• Accused Features: The complaint alleges infringement by the operation of the Accused Coal Plants, which allegedly combust coal, pyrolysis char, and a bromine-based additive before adding activated carbon sorbent (Compl. ¶211, 213).

U.S. Patent No. 10,668,430 - "Sorbents for the Oxidation and Removal of Mercury"

• Patent Identification: U.S. Patent No. 10,668,430, "Sorbents for the Oxidation and Removal of Mercury," issued March 24, 2020.
• Technology Synopsis: This patent claims a method of separating mercury where a bromine-based additive is added to the coal before it enters the combustion chamber, or is present within the chamber itself. A sorbent comprising activated carbon is then injected downstream to capture the mercury, which is subsequently separated from the gas (’430 Patent, col. 35:48-60).
• Asserted Claims: The complaint asserts at least one of claims 1-29, focusing on independent claim 1 (Compl. ¶¶ 223, 225).
• Accused Features: The complaint alleges infringement through the process at the Accused Coal Plants of combusting coal with a bromine-based additive, followed by downstream injection and collection of an activated carbon sorbent (Compl. ¶¶ 228, 230, 234).

U.S. Patent No. 10,933,370 - "Sorbents for the Oxidation and Removal of Mercury"

• Patent Identification: U.S. Patent No. 10,933,370, "Sorbents for the Oxidation and Removal of Mercury," issued March 3, 2021.
• Technology Synopsis: This patent claims a mercury separation method that requires a specific weight ratio of the halide/halogen additive to the activated carbon sorbent. The claimed ratio is between approximately 1:100 and 30:100 (’370 Patent, col. 35:55-61).
• Asserted Claims: The complaint asserts at least one of claims 1-29, focusing on independent claim 1 (Compl. ¶¶ 244, 246).
• Accused Features: The complaint alleges that Defendants' process at the Accused Coal Plants uses a weight ratio of additive to sorbent that falls within the claimed range (Compl. ¶251).

U.S. Patent No. 10,926,218 - "Sorbents for the Oxidation and Removal of Mercury"

• Patent Identification: U.S. Patent No. 10,926,218, "Sorbents for the Oxidation and Removal of Mercury," issued February 23, 2021.
• Technology Synopsis: This patent is similar to the '370 Patent but is directed specifically to iodine-based additives (HI, an iodide salt, or combinations thereof). It also requires a weight ratio of the additive to the injected activated carbon sorbent of between approximately 1:100 and 30:100 (’218 Patent, col. 35:60-col. 36:11).
• Asserted Claims: The complaint asserts at least one of claims 1-26, focusing on independent claim 1 (Compl. ¶¶ 265, 267).
• Accused Features: The complaint alleges that, in the alternative to bromine, Defendants' process uses iodine-based additives and that the weight ratio of this additive to the sorbent falls within the claimed range (Compl. ¶¶ 77, 272).

III. The Accused Instrumentality

Product Identification

• The accused instrumentalities are the mercury removal methods performed at coal-fired power plants owned and/or operated by the Defendants, including at least the Iatan, Hawthorn, La Cygne, Jeffrey Energy Center, and Lawrence generating stations (the "Accused Coal Plants") (Compl. ¶112).

Functionality and Market Context

• The complaint alleges that the Accused Coal Plants perform a multi-step process to control mercury emissions. This process involves: (1) combusting coal in a combustion chamber with a bromine-based additive (or, alternatively, an iodine-based one); (2) injecting a sorbent material comprising activated carbon into the flue gas downstream of the combustion chamber; and (3) using a particulate collection device, such as a baghouse or an electrostatic precipitator (ESP), to collect the sorbent, which has bound to the mercury (Compl. ¶¶ 76-79, 112). This process is allegedly performed to comply with federal Mercury and Air Toxics Standards (MATS), which is a regulatory prerequisite for the continued operation of such plants (Compl. ¶111).
  No probative visual evidence provided in complaint.

IV. Analysis of Infringement Allegations

U.S. Patent No. 10,343,114 Infringement Allegations

Claim Element (from Independent Claim 25)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
A method of separating mercury from a mercury-containing gas.	Defendants perform this method to comply with federal and/or state mercury regulations.	¶171	col. 33:47-49
combusting coal in a combustion chamber to provide the mercury-containing gas, wherein the coal comprises added Br2, HBr, a bromide compound, or a combination thereof, added to the coal upstream of the combustion chamber, or the combustion chamber comprises added Br2, HBr, a bromide compound, or a combination thereof.	Defendants burn coal with an added bromine-based additive either by adding it to the coal or introducing it directly into the combustion chamber.	¶173	col. 33:50-58
injecting a sorbent material comprising activated carbon into the mercury containing gas downstream of the combustion chamber.	Defendants inject an activated carbon sorbent into the flue gas after it exits the combustion chamber.	¶175	col. 33:59-62
contacting mercury in the mercury-containing gas with the sorbent, to form a mercury/sorbent composition.	Mercury present in the flue gas physically contacts the injected sorbent material within the same gas stream.	¶177	col. 33:63-65
separating the mercury/sorbent composition from the mercury-containing gas, to form a cleaned gas.	Defendants use equipment such as baghouses or electrostatic precipitators to collect the sorbent material with the captured mercury.	¶179	col. 33:66-34:1

Identified Points of Contention

• Scope Questions: A potential point of dispute may be the interpretation of "added." The claim requires that the bromine-based component be "added" to the coal or the combustion chamber. The infringement analysis may turn on evidence demonstrating that the presence of these components is due to an affirmative addition for the purpose of mercury control, rather than being naturally present in the fuel source.
• Technical Questions: A key evidentiary question will be whether Plaintiff can prove that the defendants' processes meet the specific alternative limitations of the "combusting" step: is the additive applied to the coal upstream of the chamber, or is it introduced into the chamber itself? While the claim covers both, the factual proof for each may differ in strength and availability.

U.S. Patent No. 10,596,517 Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
A method for reducing mercury in a mercury-containing gas.	Defendants perform this method at the Accused Coal Plants to comply with mercury emissions regulations.	¶192	col. 35:46-47
combusting coal in a combustion chamber, the coal comprising an additive comprising Br2, HBr, a bromide compound, or a combination thereof, to form the mercury-containing gas.	Defendants combust coal that contains an added bromine-based additive, which creates the mercury-containing flue gas.	¶194	col. 35:48-52
collecting mercury in the mercury-containing gas with a sorbent added to the mercury-containing gas, the sorbent comprising activated carbon.	Defendants add a sorbent containing activated carbon to the flue gas, which is then collected by equipment such as baghouses or electrostatic precipitators.	¶196	col. 35:53-56

Identified Points of Contention

• Scope Questions: The term "collecting mercury... with a sorbent" may be a point of construction. A question may arise as to whether the two-step process of injecting a sorbent and then capturing it in a separate piece of equipment (e.g., a baghouse) meets the single claim step of "collecting."
• Technical Questions: An evidentiary question will be whether the specific additive used by the Defendants qualifies as "Br2, HBr, a bromide compound, or a combination thereof." This raises a technical question about the chemical composition of the materials used in the accused process and whether they fall within the scope of the claim language.

V. Key Claim Terms for Construction

• The Term: "combustion chamber" (asserted in independent claims of the '114 and '517 patents)

  • Context and Importance: The claims create a spatial sequence of events occurring upstream of, inside of, and downstream of the "combustion chamber." The precise physical boundaries of this term are therefore critical to determining whether the accused methods meet the claim limitations in the required order.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The specification refers to the overall process as occurring in a "combustion system" and discusses the invention's applicability to the "flue gas from combustion systems" (’114 Patent, col. 9:59-66), which may support an interpretation that the term encompasses the entire boiler or furnace unit.
    • Evidence for a Narrower Interpretation: The patent also refers to introducing a promoter "upstream of a boiler or a combustion chamber" (’114 Patent, col. 8:60-61), which could suggest the two are distinct or that the "combustion chamber" is a specific sub-part of a larger boiler system where active combustion occurs. Figure 6, which shows a "Boiler" as a distinct unit, may be used to argue for a narrower definition.

• The Term: "sorbent material comprising activated carbon" ('114 Patent, Claim 25)

  • Context and Importance: Practitioners may focus on this term because the composition of the injected sorbent is central to infringement. Whether this term requires the sorbent to be solely activated carbon or allows it to be a mixture containing activated carbon could be dispositive.
  • Intrinsic Evidence for Interpretation:
    • Evidence for a Broader Interpretation: The use of the open-ended transitional phrase "comprising" suggests that the sorbent material can include other components in addition to activated carbon. Plaintiff may argue that as long as activated carbon is present in the injected material, this element is met.
    • Evidence for a Narrower Interpretation: A defendant may argue that the specification consistently describes the invention as using "activated carbon" as the base sorbent that is then promoted or enhanced (’114 Patent, col. 3:39-41). This could support an interpretation that the "sorbent material" must be primarily activated carbon, not a blend where activated carbon is a minor component.

VI. Other Allegations

• Indirect Infringement: The complaint alleges inducement against the parent entity, Evergy, Inc., based on its alleged control over its operating subsidiaries and its role in providing technical and financial services that facilitate the infringing activities (Compl. ¶¶ 114-115, 181). Inducement is also alleged against Defendants who co-own but do not operate an accused plant, based on allegations that they direct and pay the operating agent to perform the patented methods to ensure regulatory compliance (Compl. ¶182).
• Willful Infringement: Willfulness allegations are based on Defendants' alleged pre-suit knowledge of the patents-in-suit. The complaint cites multiple specific instances of communication, beginning on August 2, 2016, where Plaintiff allegedly informed Defendants of its patented technology (Compl. ¶¶ 153-157, 161). The complaint also points to the prior Delaware jury verdict of willful infringement as evidence that Defendants knew or should have known their actions would constitute infringement (Compl. ¶69).

VII. Analyst’s Conclusion: Key Questions for the Case

• A core issue will be one of evidentiary proof: can Plaintiff produce sufficient technical evidence from Defendants' power plants to demonstrate that the accused processes meet every limitation of the asserted claims? This will be particularly crucial for the patents that recite specific weight ratios ('370 and '218 patents) or distinguish between bromine and iodine additives ('218 patent).
• A key legal question will be one of corporate liability: beyond the direct infringement of the entities operating the power plants, can Plaintiff establish that the parent corporation and non-operating co-owners exercised the specific intent and control required to be held liable for induced infringement under 35 U.S.C. § 271(b)?
• The case may also turn on a question of claim scope: how broadly will the court construe key terms such as "combustion chamber" and "additive comprising...a bromide compound"? The outcome of claim construction will directly impact the breadth of activities that can be found to infringe.