Byesville, Ohio
The Guernsey Power Station is a 3-unit, modern, highly efficient natural gas-fired facility in Byesville, OH.
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Chief Nuclear Officer
Edward Casulli serves as Talen Energy’s Chief Nuclear Officer, responsible for overseeing all aspects of the company’s Susquehanna nuclear power plant, a two-unit, approximately 2,500-megawatt station in Salem Township, Luzerne County, Pennsylvania.
Mr. Casulli has nearly 30 years of nuclear industry experience. Before assuming his current role in December 2025, he served as Site Vice President at Susquehanna, where he was responsible for all plant operations and personnel. Prior to joining the company in early 2023, he had a long-tenured career with Public Service Enterprise Group’s Hope Creek Nuclear Generating Station, where he held roles of increasing importance, including Vice President, Operations Shift Supervisor, Senior Manager, Plant Engineer, Senior Director – Operations, and Executive Director – Plant Manager.
A graduate of the University of Pennsylvania, Mr. Casulli earned an Executive Master of Science degree in Management of Technology. He is a veteran of the U.S. Navy and received a Bachelor of Science degree in Electrical Engineering from the U.S. Naval Academy before enrolling in the Naval Nuclear Propulsion Program, where he reached the rank of lieutenant.
Vice President – Environmental Affairs
Megan Toomey serves as Vice President of Environmental Affairs for Talen Energy. In this capacity, she leads environmental operations, policy, compliance and advocacy efforts for the company’s 10.7 -gigawatt fleet of nuclear, natural gas, oil, and coal-fired generation facilities, as well as its other assets. Prior to her current role, she led Talen’s Environmental Projects group and held leadership roles in the company’s fossil engineering and regulatory teams.
Ms. Toomey has been in the energy industry for nearly 20 years, working for Burns & McDonnell and PPL Corporation prior to joining Talen. Her career has afforded her the opportunity to develop expertise in a wide range of areas -including engineering, thermal power plant operations and maintenance, environmental compliance and regulatory advocacy, and state government relations.
A graduate of Iowa State University, Ms. Toomey holds a Bachelor of Science degree in Chemical Engineering.
Vice President – External Affairs
Julie LaBella serves as Talen Energy’s Vice President of External Affairs. She is responsible for leading the company’s advocacy efforts related to state and federal policy and oversees Talen’s corporate communication function.
Ms. LaBella has more than two decades of experience in the energy industry. In addition to her current responsibilities, she held leadership roles in the areas of commodity risk management, compliance, and financial analysis. She began her career at PPL Corporation, where she spent nearly 15 years as a leader within corporate risk management, providing oversight for commodity risk and its enterprise risk management function. She continued in that role with Talen Energy in 2015.
After joining Talen, Ms. LaBella later transitioned into a leadership position within the company’s Regulatory and External Affairs department. Within this team she now leads advocacy efforts and drives policy solutions to promote and protect the interests of the company and its 12 generating facilities located in five states. She also co-chairs the company’s nuclear decommissioning trust committee which provides oversight and guidance on the investment activities of the fund.
Ms. LaBella holds a bachelor’s degree in Finance from Indiana University of Pennsylvania and a master’s degree in Business Administration, Finance and Accounting from St. Bonaventure University.
Active in the community, she currently serves as Treasurer on the Board of Directors and as Chair of the Finance Committee at the Third Street Alliance for Women and Children and is a member of the Impact Council at the United Way of the Greater Lehigh Valley.
Chief Development Officer
Darren Olagues serves as the Chief Development Officer for Talen Energy. In this capacity, he leads the company’s corporate strategy and development activities.
Mr. Olagues has over 25 years of energy experience, serving in a variety of leadership roles throughout his career. Before joining Talen Energy, he was Chief Financial Officer and Senior Advisor for independent power producer GenOn Energy, where he currently serves on the Board of Directors. Mr. Olagues also held various leadership roles with Cleco affiliated companies, including President and CEO of Cleco Corporate Holdings and President of Cleco Power where he led its $4.7 billion take private transaction. Prior to his tenure with Cleco, he held financial leadership roles at Exelon Corporation and Sithe Energies.
A graduate of Tulane University, New Orleans, Mr. Olagues has bachelor’s degree in Accounting and Business/Management.
Senior Vice President, Regulatory and External Affairs
Jennifer Mansh serves as Senior Vice President, Regulatory and External Affairs for Talen Energy. She is responsible for the development and implementation of federal regulatory and policy strategies, as well as overseeing regulatory and NERC compliance for Talen and its subsidiaries.
Ms. Mansh has worked in the energy industry for almost 20 years. Most recently, she served as Counsel with Vinson & Elkins, where she represented electric utility companies, merchant transmission companies, wholesale power marketing companies, financial institutions, and generation companies in rate, licensing, and enforcement proceedings before FERC. Prior to joining Vinson & Elkins, she was a Senior Associate Attorney with Gibson, Dunn & Crutcher LLP for almost a decade, where she was recognized in “The Best Lawyers in America: One to Watch” for Energy Law.
Ms. Mansh began her career working at Exelon Corporation’s wholesale marketing division at the time, called Power Team, where she was a Senior Financial Analyst.
Ms. Mansh graduated cum laude from Bryn Mawr College in Pennsylvania with a Bachelor of Arts degree in Economics. She received her Juris Doctorate with honors from Washington University in St. Louis School of Law. She is a member of the Pennsylvania and District of Columbia Bar Associations and is admitted to practice in Pennsylvania and the District of Columbia.
In the community, Ms. Mansh is a member of the Board of McLean MOMs.
Vice President, Finance
Katie Sussen serves as Vice President, Finance for Talen Energy. In this role she leads the Company’s financial planning and analysis, plant finance, and supply chain functions and is responsible for its long-term planning activities.
With over 15 years of experience in the energy industry, Ms. Sussen has deep experience in the competitive power generation sector. Prior to joining Talen, she served in senior finance roles at NRG Energy, Inc., GenOn Energy, Inc., and Dynegy, a subsidiary of Vistra Corp.
Ms. Sussen holds Bachelor of Accounting and Master of Business Administration degrees from Southern Illinois University at Carbondale and is a Registered Certified Public Accountant in the state of Illinois.
Senior Director, Investor Relations
Ellen Liu is Talen Energy’s Senior Director of Investor Relations. In that capacity, she establishes and manages the company’s relationships with shareholders, prospective investors, and research analysts, oversees strategic communications with the financial community, and leads key areas of the quarterly reporting process.
Prior to joining Talen, Ms. Liu was a Vice President at Jefferies in the Energy Investment Banking group. In her six years there, she advised on M&A, public and private financings, and other strategic alternatives for energy companies. She also oversaw intern recruiting and analyst staffing. Ms. Liu joined Talen in 2019 as Director of Corporate Development, managing transactions and special projects.
Ms. Liu holds a bachelor’s degree in Economics and Statistics from Rice University and an MBA from Stanford Graduate School of Business.
Vice President and Treasurer
Sergio Castro serves as Vice President and Treasurer for Talen Energy. In this role, he leads the company’s treasury, capital markets, and investor relations functions.
Mr. Castro has significant experience in financial leadership roles within the energy sector. Prior to joining Talen, he served as Chief Financial Officer for Otto Energy where he oversaw all areas of the Finance organization. During his tenure with Contango Oil & Gas Company, Mr. Castro held positions of increasing importance, including Assistant Treasurer, Vice President & Treasurer, and Chief Financial Officer, and played key roles in several mergers and acquisitions, capital raises, and asset divestiture transactions.
A summa cum laude graduate of the University of Houston, Mr. Castro holds a bachelor’s degree in Accounting and is a Certified Public Accountant and Certified Fraud Examiner. He also proudly served in the United States Navy prior to pursuing his undergraduate studies.
Vice President, Risk Management
Olivia Sigo serves as Talen Energy’s Vice President of Risk Management. She is responsible for the risk management function, including market risk, trade control activities, position reporting, P&L reporting, enterprise risk management, and credit risk management activities for the overall Company.
Ms. Sigo has over a decade of experience in the energy and power industry, with responsibilities including financial analysis, business management, and derivative sales. She began her career at Merrill Lynch, where she held various roles, including serving as an analyst for the commodities sales team. After Merrill Lynch, she spent over eight years at Deutsche Bank, where she was responsible for the overall management of the North American power and gas trading business, including facilitating growth initiatives, managing risk, and ensuring best practices and infrastructure were in place. Ms. Sigo joined Talen Energy in January 2018, where she eventually served as finance lead for over 3GW of generation.
Ms. Sigo holds a bachelor’s degree in Finance from the University of Houston-Downtown.
Senior Vice President and Chief Accounting Officer
Anthony “Tony” Plagens serves as Talen’s Senior Vice President and Chief Accounting Officer. In this role, he leads the company’s accounting, tax, and external financial reporting activities. Mr. Plagens has 20 years of combined energy industry and public accounting experience and joined Talen in September 2017 as Managing Director and Corporate Controller.
Prior to joining Talen Energy, he served as North American Controller for Mercuria Energy Trading. He also served in accounting management capacities at companies including ConocoPhillips, BP, and Ernst & Young across a variety of geographies throughout the U.S., U.K., and China.
A graduate of Albion College in Albion, Michigan, Mr. Plagens holds a B.A. in Economics and Management and is a Certified Public Accountant.
Chief Administrative Officer
Andrew “Andy” Wright was appointed as Talen Energy’s first Chief Administrative Officer in June 2023 after having served as the Company’s General Counsel and Corporate Secretary since June 2018. In this capacity, Mr. Wright oversees the Company’s Human Resources, Information Technology, Facilities, and Corporate Security functions.
Prior to joining Talen Energy, Mr. Wright spent 14 years as in-house counsel for Energy Future Holdings (EFH) Corp., most recently as Executive Vice President, General Counsel and Corporate Secretary.
Mr. Wright has a wealth of experience in the power generation space with an intimate knowledge of the financial, operational, and regulatory challenges facing the industry. He has led numerous fleet and balance sheet restructuring efforts, complex acquisitions and divestures, high-stakes litigation, and regulatory reviews. His experience includes being involved in the largest leveraged buyout in U.S. history and some of the largest financial restructurings in the industry. He also has worked closely with the board of directors at Talen Energy and EFH.
After receiving his Juris Doctorate from the University of Notre Dame, Mr. Wright went into private practice with Vinson & Elkins in both Dallas, Texas and London, England with a focus on corporate securities, mergers and acquisitions, and corporate governance.
Prior to pursuing his law career, he received a degree in Accounting from Southern Methodist University, obtained his CPA and practiced as an accountant with KPMG in Chicago, Illinois.
General Counsel and Corporate Secretary
John Wander joined Talen Energy in June 2023 as General Counsel and Corporate Secretary. In this position he leads the Company’s Legal and Regulatory and External Affairs functions, oversees corporate governance, and serves as the primary point of contact for its Board of Directors.
Mr. Wander has nearly 30 years of experience in commercial law with cases primarily pertaining to finance, accounting, and shareholder issues. Prior to joining Talen, he served as Partner – Shareholder Litigation & Enforcement for Vinson & Elkins and as the firm’s General Counsel. Since joining the firm in 1994, he worked on some of its most high-profile, high-stakes litigation matters, and focused his practice on commercial litigation in the accounting, securities, manufacturing, and insurance industries, routinely representing issuers and accounting firms before the Securities & Exchange Commission. He also tried numerous corporate governance cases in the Delaware Chancery Court. Mr. Wander variously held several leadership positions, including Managing Partner of the Dallas office, Co-Department Head of Litigation and Regulatory, Co-Practice Group Leader of Complex Commercial Litigation, and a member of the Management Committee.
Throughout his career, Mr. Wander has received a variety of accolades including multi-year recognition from Chambers USA in the areas of Litigation: Securities (Texas) from 2014–2022 and Litigation: White Collar Crime & Government Investigations from 2017–2022. He also was named one of the “Best Lawyers in Dallas” by D Magazine, one of The Best Lawyers in America® Commercial Litigation (Dallas) by BL Rankings, LLC from 2013–2023, as a top attorney in Texas from 2011–2020 and 2022 by Super Lawyers (Thomson Reuters), and as a member of its Texas Rising Stars list from 2004–2006. He also was named to the Global Investigations Review (GIR) 100 in 2020.
A graduate of the University of Texas School of Law, Mr. Wander received his Juris Doctorate with honors in 1994. He also received a Bachelor of Arts degree from Northwestern University, Evanston, Ill. He is a member of the American Bar Association and Dallas Bar Association. Mr. Wander is admitted to practice in Texas, all U.S. District Courts in Texas and Arkansas, and the Fifth Circuit Court of Appeals.
In the community, Mr. Wander has served on the Board of Directors for Vogel Alcove, which provides services for Dallas’ homeless children and families, since 2009 and as its Chair from 2018- 2020. He has served as a member of the Board of Trustees for The Center for American and International Law, the University of Texas School of Law Alumni Association Executive Committee, and the University of Texas Chancellor’s Council Executive Committee.
President
Terry Nutt serves as President of Talen Energy Corporation. In this capacity, he is responsible for overseeing the daily operations of the company’s business, including plant operations, commercial activities, administrative functions, regulatory, and other external stakeholder engagements.
Mr. Nutt has over 25 years of experience in the energy industry, including time spent at independent power producers and energy trading firms. Prior to assuming his current role with the company, he served as Talen’s Chief Financial Officer from July 2023 through December 2025. From 2018 until 2023, he served as Chief Financial Officer and Managing Director for EDF Trading North America, the energy commodity trading subsidiary of Électricité de France (EDF) S.A., a multinational energy utility headquartered in France. Prior to his service at EDF, Mr. Nutt served in multiple senior finance positions at Vistra Corporation (and its predecessor entities), including as Senior Vice President and Controller and Senior Vice President of Risk Management. Previous to his time at Vistra, Mr. Nutt worked in various finance roles at Dynegy Inc.
Mr. Nutt earned his M.S. in Accounting and his B.B.A., summa cum laude, from Texas A&M University.
Chief Financial Officer
Mr. Muller has held multiple leadership roles during his tenure with Talen. Prior to assuming his current role in December 2025, he served as Executive Vice President, Strategic Ventures, leading the company’s strategic direction related to digital infrastructure development and data center contracting. Previous to that, he led the company’s PJM Fossil business unit, where he was responsible for over eight gigawatts of PJM generation assets in Pennsylvania, Maryland, and New Jersey.
Before joining Talen in 2018, he was an Associate Partner for McKinsey & Co., advising energy clients, including Talen, on strategic opportunities and operational transformations. He also previously served as a submariner in the U.S. Navy.
A graduate of the U.S. Naval Academy, Mr. Muller holds a Bachelor of Science degree in Mathematics. He received his MBA from The Wharton School and his JD from the University of Pennsylvania.
Chief Commercial Officer
Chris Morice was appointed Chief Commercial Officer of Talen Energy in 2023, overseeing the Company’s wholesale trading and fleet optimization activities.
With 15 years of profitable leadership, Mr. Morice began his career in New York City at Lehman Brothers before moving to Houston with Lehman’s acquisition of Eagle Energy Partners in 2009.
Mr. Morice joined Talen in 2017 as Desk Head/Lead Trader, tasked with P&L responsibilities, managing numerous products across multiple regions. Prior to joining Talen, he worked exclusively in market-facing, risk-taking, revenue-generating roles at Koch Energy, Topaz Power, and EDF Trading.
Mr. Morice holds a bachelor’s degree from the University of Missouri, Columbia and a master’s degree from Fordham University, Bronx.
Chief Asset Development Officer
Dale Lebsack serves as Chief Asset Development Officer for Talen Energy. In this capacity, he is responsible for assessing, designing, and constructing new generation assets for the company, as well as developing site opportunities for new generation and large load interconnections.
Mr. Lebsack joined Talen in 2015 as part of its acquisition of RJS Power from affiliates of Riverstone Holdings, LLC, and since joining the company, he has taken on roles of increasing importance. Before assuming his current role in December 2025, he served as Talen’s Chief Fossil Officer, leading the company’s approximately 10-gigawatt fossil generation fleet. Prior to that, he was the business unit leader for Talen’s generation assets in Montana, ERCOT, and the Northeast and the company’s Senior Vice President, Fossil Operations.
Mr. Lebsack held various leadership roles with RJS Power and its affiliates in asset management, project development, plant operations, and environmental, health and safety. In those roles, he led the technical planning and permitting related to a $1.2 billion repowering of three power plants in Texas; managed the conversion to biomass of a coal-fired plant in North Carolina; and led the technical due diligence related to the acquisition of a gas asset portfolio in New Jersey and a coal asset portfolio in Maryland. Apart from his roles with RJS Power, Mr. Lebsack’s experience includes plant-level positions with Duke Energy North America and Entergy.
A graduate of Georgia Institute of Technology, Mr. Lebsack earned a B.S. in Mechanical Engineering.
Chief Operating Officer
Brad Berryman serves as Talen Energy’s Chief Operating Officer, responsible for overseeing the company’s generation fleet, which is primarily located in the Mid-Atlantic and Ohio.
Prior to assuming his current role in December 2025, Mr. Berryman served as Talen’s Senior Vice President and Chief Nuclear Officer for seven years. In this role, he oversaw all aspects of the company’s Susquehanna nuclear power plant. He joined the company in early 2017 as Site Vice President, and was central to Susquehanna moving from a third quartile to a top decile industry ranking based on its operational, financial, and safety performance.
With three decades of extensive commercial nuclear experience, Mr. Berryman has held positions of increasing importance spanning various technical, operational, training, and financial capacities. Prior to joining Talen, he served as General Manager at Turkey Point Nuclear Generating Station. He also held leadership roles at Wolf Creek Nuclear Operating Corporation, Palo Verde Nuclear Generating Station, and Arkansas Nuclear One. In addition, he proudly served his country in the United States Navy as part of the submarine fast attack fleet.
Mr. Berryman earned his B.S. in Organizational Management from Central Baptist College.
Active in the community, Mr. Berryman serves on the board of the United Way of Wyoming Valley and participates in a variety of company volunteer initiatives.
Chief Executive Officer and Director
Mark (“Mac”) McFarland is the Chief Executive Officer of Talen Energy Corporation. He was appointed to the role in May 2023 and concurrently joined the company’s Board. In his capacity as Chief Executive Officer, Mr. McFarland oversees all aspects of the company’s long-term strategic direction.
Mr. McFarland previously served as President and Chief Executive Officer as well as Chairman of the Board of California Resources Corporation (CRC), an independent energy and carbon management company committed to energy transition. He continues to serve on the Board of CRC and Chairs Carbon TerraVault, a wholly owned subsidiary of CRC. Prior to his roles with CRC, he was Executive Chairman of GenOn Energy, an independent power producer. He also served as their President and Chief Executive Officer from April 2017 to December 2018 and continued on as a member of their Board the until September 2022. From 2013 to 2016, he served as Chief Executive Officer of Luminant Holding Company LLC, a subsidiary of Energy Future Holdings Corporation, a large independent power producer. From 2008 to 2013, he served as both Chief Commercial Officer of Luminant and Executive Vice President, Corporate Development and Strategy of Energy Future Holdings. From 1999 to 2008, Mr. McFarland served in various roles at Exelon Corporation, including as Senior Vice President, Corporate Development.
Currently, Mr. McFarland serves on the Board of Directors of the Nuclear Energy Institute, and previously served on the Boards of TerraForm Power, Bruin E&P Partners, and Chaparral Energy.
Mr. McFarland earned his Master of Business Administration Degree from the University of Delaware and a Bachelor of Science degree in Civil Engineering (Environmental Concentration) from Virginia Polytechnic Institute and State University. He received his professional engineer license in 1995.