America’s Premier Competitive Power Company
... Creating Power for a Sustainable Future
Thad Hill became Calpine’s Chief Executive Officer and a member of its Board of Directors in May 2014. Mr. Hill joined the company in September 2008 as Executive Vice President and Chief Commercial Officer. He became Chief Operating Officer in November 2010 and was named President in December 2012. Prior to Calpine, Mr. Hill was with NRG Energy from 2006 to 2008, serving as President of NRG Texas in 2007- 2008. Prior to NRG, Mr. Hill was Executive Vice President of Strategy and Business Development at Texas Genco LP from 2005 to 2006. From 1995 to 2005, he was with Boston Consulting Group Inc., where he rose to Partner and Managing Director and led the North American energy practice, serving companies in the power and gas sector with a focus on commercial and strategic issues. Mr. Hill received his Bachelor of Arts degree from Vanderbilt University magna cum laude and a Master of Business Administration degree from the Amos Tuck School of Dartmouth College, where he was elected an Edward Tuck Scholar.
Andrew Novotny was appointed President of Calpine in May 2023, expanding his existing role as the Company’s Chief Operating Officer held since January 2021. Andrew also serves as President of Calpine Energy Services, Calpine’s wholesale trading and marketing subsidiary. In these roles, Andrew is responsible for Calpine’s wholesale commercial activity, power operations and administrative services functions. Prior to his current role, Andrew served as Executive Vice President of Commercial Operations, co-leading the company’s wholesale commercial operations and analytics functions while also providing oversight to Calpine's ISO and RTO advocacy across North America. Andrew joined Calpine in April 2012 as Vice President of Power Trading, holding a variety of trading leadership roles since that time. Before joining Calpine, Andrew served as Vice President of Financial Gas and Power Trading for the BG Group and Vice President at Duke Energy. Andrew holds a Bachelor of Arts from Vanderbilt University, graduating magna cum laude with high honors in Economics. He also received a Master of Business Administration from Rice University, where he was named a Jones Scholar.
W. Thaddeus Miller joined Calpine Corporation in August 2008 as Executive Vice President, Chief Legal Officer and Secretary. In March 2018, he was named Executive Vice Chairman of Calpine’s Board of Directors. Mr. Miller brings decades of legal and energy industry experience to Calpine. He previously served as Executive Vice President and Chief Legal Officer of Texas Genco Inc. until 2006. From 2002 to 2004, Mr. Miller was a consultant to Texas Pacific Group, a private equity firm. From 1998 to 2002, he served as Executive Vice President and Chief Legal Officer of Orion Power, an independent power producer. From 1994 to 1998, Mr. Miller was Vice President of Goldman Sachs & Co., where he focused on wholesale electric and other energy commodity trading. Before joining Goldman Sachs & Co., Mr. Miller was a partner in a New York law firm. Mr. Miller currently serves on the board of RMG Acquisition Corp. since December 2019. Mr. Miller earned his Bachelor of Science degree from the United States Merchant Marine Academy and his Juris Doctor from St. John's School of Law. In addition, he was an officer in the United States Coast Guard.
Zamir Rauf has served as Executive Vice President and Chief Financial Officer since December 2008. Mr. Rauf previously was interim Chief Financial Officer and Treasurer from June 2008 to December 2008. Prior to his role as Interim CFO, Mr. Rauf was Senior Vice President, Finance and Treasurer at Calpine. In that position, he had responsibility for Calpine's corporate and project finance, treasury and debt compliance functions and managed the corporate banking, investment banking and rating agency relationships. Prior to Calpine, Mr. Rauf held various accounting and finance roles with Enron North America and Dynegy Inc., as well as Comerica Bank in both credit and lending roles. He earned his Bachelor of Arts degree in business and commerce and master's degree in business administration-finance from the University of Houston.
Caleb Stephenson has served as an Executive Vice President of Commercial Operations since March 2018. In this role, he leads the wholesale commercial and analytics function. He is responsible for the teams who develop wholesale customer relationships and new power projects, as well as those who support the company with information technology applications and infrastructure. Mr. Stephenson joined Calpine in October 2008 as Vice President of Commercial Analytics. He became Senior Vice President of Commercial Analytics in May 2014 and added wholesale origination to his responsibilities in February 2017. He came to Calpine from PA Consulting Group’s Global Energy Practice, where he advised merchant power industry participants on energy market outlook and risk management issues. He holds a Master of Business Administration in finance from Washington University.
Hether Benjamin Brown has served as Calpine’s Executive Vice President and Chief Administrative Officer since July 2022. In this role, she oversees the company’s Corporate Communications, Facilities, Human Resources, Information and Physical Security, and Supply Chain Services functions. Ms. Benjamin Brown previously served as Calpine’s Senior Vice President and Chief Administrative Officer beginning in May 2014. She was named Senior Vice President of Human Resources beginning in February 2012. In this role, she led staffing and talent acquisition, organizational development, and compensation and benefits. She joined Calpine in May 2009 as Vice President of Supply Chain Services, and in that position she transformed and centralized Calpine’s supply chain function to improve efficiency, lower costs and leverage the company’s size and scale nationally. Prior to joining Calpine, she was Director of Supply Chain Management for the University of Texas M.D. Anderson Cancer Center. Previously, Ms. Benjamin Brown served in leadership roles of increasing responsibility at other public- and private-sector organizations in the aerospace/defense, environmental/waste and information technology industries. She holds a Bachelor of Arts in political science from the University of Texas at Arlington and a Master of Business Administration from Texas Women’s University.
Mike Del Casale has served as Calpine’s Executive Vice President of Power Operations since January 2023. Previously, he served as the company’s Senior Vice President of Power Operations since October 2017, and his role was expanded in January 2021 to include Asset Performance Management. Previously, Mr. Del Casale had served as Vice President of Regional Operations and Construction since October 2016 and as Vice President of Engineering and Construction beginning in February 2015. Mr. Del Casale joined Calpine as a part of the Conectiv Energy acquisition in 2010 and earlier served as Calpine’s East Region Asset Manager and Plant Manager at the York Energy Center. Before the acquisition, he was involved with a number of plant construction and commissioning projects along with other operations and engineering positions throughout his career. Mr. Del Casale worked at the Philadelphia Naval Shipyard for several years before joining Delmarva Power and Light, which later become Conectiv Energy. He has a bachelor’s degree in mechanical engineering from Villanova University.
Rosemary Antonopoulos was named Senior Vice President Administrative Services in May 2023 and oversees the Company’s Human Resources and Corporate Communications functions. Prior to her current role, Rosemary served as Vice President and Deputy General Counsel for Calpine’s West region. Rosemary joined Calpine in 2004 as an Associate Counsel and later became Managing Counsel. In 2009, she assumed leadership of Calpine’s West legal team as Vice President Assistant General Counsel. Most recently, she led Calpine’s West Legal team responsible for supporting the Company’s West origination and commercial transactions; gas-fired and geothermal power operations; construction and development of gas-fired, battery and Carbon Capture and Sequestration projects. Prior to joining Calpine, Rosemary was an attorney at a San Francisco-based law firm. Rosemary earned a Bachelor of Arts in International Relations at Marquette University and her law degree from George Washington University Law School.
As Senior Vice President of Development Engineering and Construction Services since January 2023, Rick Colgan oversees development engineering and construction services supporting Calpine’s installed fleet and new growth projects. This includes support of Calpine’s Carbon Capture and Sequestration (CCS) and renewables development efforts. Previously, Mr. Colgan served as Calpine’s Senior Vice President of Fleet Services since October 2017 where he led the company’s Turbine Outage Services, Engineering and Construction groups. Since joining Calpine in 1996, Mr. Colgan has held various leadership roles in plant operations, Asset Management, Regional Operations and Fleet Services. Mr. Colgan studied industrial engineering at the University of Wyoming and served in the U.S. Navy.
Sean Fallmer has served as President of Calpine’s commercial and industrial retail subsidiary, Calpine Energy Solutions, since January 2023. Prior to his current role, Mr. Fallmer served as Senior Vice President of Pricing and Structuring for Calpine’s retail platform where he oversaw commodity supply and operations, portfolio management and environmental products. Mr. Fallmer joined Calpine Energy Solutions in 2016 as part of the Noble Americas Energy Solutions acquisition. During his time at Noble, he was Regional Vice President leading the Northeast and Midwest supply and structuring desks. He joined Noble Solutions’ predecessor company Sempra Energy Solutions in 2007. Mr. Fallmer began his career as a commodity futures trader and member of the Chicago Mercantile Exchange before transitioning to leading commodity risk management and derivative engagements with Fortune 500 firms as a member of KPMG’s Financial Risk Management group. Mr. Fallmer earned a Bachelor of Science in Business with a concentration in Finance from the University of Arizona and a Master of Business Administration from the University of Chicago.
James Henahan has served as Calpine’s Senior Vice President of Commercial Analytics since February 2022. In this role, Mr. Henahan oversees market analytics, pricing and asset optimization. Mr. Henahan began his career with General Electric, where he earned three patents related to power plant systems. He joined Calpine in July 2010 as Manager of Dispatch Analysis and has held various roles with increasing responsibility during his tenure. Mr. Henahan holds both a Bachelor of Science and Master of Science in Mechanical Engineering from the University of Michigan, as well as a Master of Business Administration from the Indiana University Kelley School of Business. He also completed the Advanced Management Program at the Tuck School of Business at Dartmouth.
Bryan Kimzey has served as Calpine’s Senior Vice President of Finance and Treasurer since March 2018. In this role, he is responsible for Calpine’s treasury function, credit, financial planning and analysis, and relationships with Calpine’s debt investors. Previously, Mr. Kimzey had served as Vice President of Investor Relations and Financial Planning since January 2015. He joined the company as Vice President of Investor Relations at Calpine in September 2011. Prior to Calpine, Mr. Kimzey was with Progress Energy, Inc., from 2004 to 2011, serving in various roles in Investor Relations, Treasury and Strategic Planning. Prior to Progress Energy, Inc., Mr. Kimzey was with Credit Suisse First Boston from 1998 to 2004, where he rose to Vice President in the firm’s investment banking group in New York, serving companies in the power and gas sectors with a focus on mergers, acquisitions and underwriting. He began his career in 1996 with Arthur Andersen, where he audited energy marketing and trading businesses in Houston. Mr. Kimzey received his Bachelor of Science degree in business administration and his Master of Accounting degree from the University of North Carolina at Chapel Hill.
Jeff Koshkin has served as Calpine’s Senior Vice President and Chief Accounting Officer since August 1, 2015, and gained additional responsibility as Chief Risk Officer in March 2018. He joined Calpine in December 2008 and has served in a number of leadership roles including the Controller of Commercial Operations and Controller of Corporate and Plant Accounting, as well as in interim roles heading Financial Planning and Analysis and as Chief Risk Officer. Prior to Calpine, Mr. Koshkin was a Senior Manager in the Regulatory and Capital Markets practice for Deloitte and Touche, LLP. He holds a master’s degree in Professional Accounting from the University of Texas at Austin. Mr. Koshkin is a Certified Public Accountant and a member of the American Institute of Certified Public Accountants and the Texas Society of Certified Public Accountants.
Tom Long was named Calpine’s Senior Vice President of Asset Performance Management and Outage Services in January 2023. Previously, Mr. Long served as Calpine’s Senior Vice President of Asset Performance Management since October 2016. Since joining Calpine in 2000 as part of the company’s acquisition of SkyGen Energy, Mr. Long has also held leadership roles in development, engineering, construction, procurement, and analytics. Mr. Long holds a Bachelor of Science in Mechanical Engineering from Iowa State University and an MBA from the University of Illinois at Chicago.
Alex Makler has served as Senior Vice President of Calpine’s West Region since May 2014. In this role, he leads the company’s commercial team in California and the West, and he collaborates with the Government & Regulatory Affairs team on policy and advocacy efforts in the region. Previously, Mr. Makler served as Calpine’s Vice President of Strategic Origination and Development for the West Region from January 2009 to May 2014. He joined Calpine’s legal department in 1999, where he served as the company’s lead attorney for California energy crisis matters and became Vice President and Assistant General Counsel. He has a background in commercial transactions, project financing, federal and state regulatory activities, legislative issues, mergers and acquisitions, and all aspects of electric generation development. Prior to Calpine, Mr. Makler practiced commercial law with major law firms in New York, Houston and San Francisco. He earned both a Bachelor of Arts degree in Political Economy and a law degree from the University of California, Berkeley.
Kevin G. McMahon serves as Senior Vice President, Internal Audit and Chief Compliance Officer. He joined Calpine in May 2006 to lead the Internal Audit function and took on the added role of Chief Compliance Officer in August 2009. Mr. McMahon is responsible for managing and conducting all internal audit activities, supporting operations and the functional departments as requested, managing the Sarbanes Oxley (SOX) compliance oversight program, leading records management activities and reporting audit findings with the appropriate recommendations to senior management and the Audit Committee. In addition, he oversees the company’s regulatory compliance efforts with particular emphasis on ensuring that proper procedures are in place to help the company meet all FERC and NERC regulatory requirements. Prior to joining Calpine, he was Vice President and General Auditor for Exide Technologies, a global manufacturer of stored electrical energy products and services for industrial and transportation applications. He previously served as Vice President-Internal Audit Services and in other senior auditing positions for HCA, Inc., the largest hospital provider in the United States, and served in senior management and auditing positions for Ernst & Young LLP, Southern Company Services, FPL Group and HSBC/Marine Midland Bank N.A. Mr. McMahon has a Master of Business Administration degree from Palm Beach Atlantic University and a Bachelor of Science degree in accounting from the State University of New York. He is both a Certified Internal Auditor (CIA) and Certified in Risk Management Assurance (CRMA).
Sarah Novosel is Senior Vice President of Government Affairs and Managing Counsel for Calpine. She manages Calpine's Washington, D.C., office and directs its federal regulatory practice. Ms. Novosel has been practicing energy law for more than 25 years. She began her career in 1991 with the law firm of Bracewell & Patterson in Washington, D.C., where she represented natural gas and power marketing clients. After leaving Bracewell & Patterson in 1997, Ms. Novosel joined Enron Corp. and later worked for American Electric Power. She joined Calpine in 2004 as Senior Regulatory Counsel and was promoted in 2007 to her present position. A graduate of the University of Maryland with a bachelor's degree in Government and Politics, Ms. Novosel earned her law degree from Georgetown University Law Center. She is a member of the Maryland State Bar, the District of Columbia Bar and the Energy Bar Association.
Rick Peña leads Calpine’s merger and acquisition activities as well as the integration of acquired businesses. His accomplishments at Calpine have included negotiating acquisitions and divestitures of power plants that advanced the company’s strategic priorities of building scale in key competitive markets, as well as the acquisition of retail platforms that provide more direct channels to our power customers. Mr. Peña joined Calpine in June 2007 as a Director of Strategic Origination, serving our Southeast, ERCOT and North regions over the years. He was named Vice President of Corporate Development in January 2013. Prior to joining Calpine, Mr. Peña served as Manager of Mergers and Acquisitions for Direct Energy and as a Senior Analyst, Commercial Services, at Duke Energy North America. He earned his bachelor’s degree in Finance from Texas A&M University.
Katherine Piper has served as Calpine’s Senior Vice President, General Counsel and Corporate Secretary since April 2022. In this role, she advises the company’s leadership on legal, regulatory and corporate governance matters, in addition to leading the company’s legal department. Ms. Piper joined the company in January 2012, and most recently served as Vice President, Assistant General Counsel and Corporate Secretary. From 2003 through 2011, Ms. Piper practiced at large international law firms, where she represented clients in complex litigation and corporate restructuring matters, including in the energy sector. Prior to entering private practice, Ms. Piper also served as a judicial law clerk for the United States Bankruptcy Court for the District of Maryland. Ms. Piper received her law degree from American University, Washington College of Law, where she graduated summa cum laude, and her bachelor’s degree, with high honors, from the University of California, Santa Barbara.
Steven Schleimer has been Calpine’s Senior Vice President for Government and Regulatory Affairs since January 1, 2014. He had previously served as Vice President of Government and Regulatory Affairs for Calpine’s North Region since 2010. From 2006 to 2010, Mr. Schleimer was Vice President at Barclays Capital in New York and was responsible for market design and regulatory issues. Prior to that, he had served as Calpine’s Vice President of Market and Regulatory Affairs in the West Region from 2000 to 2006. Mr. Schleimer spent the first 12 years of his career at Pacific Gas and Electric Company. He earned a master’s degree and a bachelor’s degree, with highest honors, in Economics from the University of California at Santa Cruz.
Will Stokes is responsible for all regional power trading in the strategic wholesale markets where Calpine operates. He joined the company in October 2009 as Vice President of Strategy. In June 2010, he went on to lead the East Trading Desk and more recently the West Trading Desk. Mr. Stokes came to Calpine from NRG, where he served in various leadership positions. He was Director of Business Development and Strategic Planning at Texas Genco, LLC, prior to its acquisition by NRG in 2006 and previously gained power industry experience through leadership positions at Merrill Lynch Commodities, Energy-Koch and the Boston Consulting Group. He holds a Bachelor of Science in Accounting and Spanish from Trinity University and a Master of Business Administration from Northwestern University.
Michael Sullivan has led Calpine’s retail business, Champion Energy, as President and Chief Executive Officer since March 2016 and North American Power since January 2017. He joined Champion Energy as Senior Vice President of Operations in 2008 and was promoted to Chief Operating Officer in 2010. In that role, he was responsible for all aspects of the company’s day-to-day operations, including commercial and residential sales, wholesale supply and customer operations. Prior to joining Champion Energy, Mr. Sullivan was a founding partner of Ambridge Energy, LLC, which merged with Champion Energy in June 2008. Prior to founding Ambridge, he held several roles at Reliant Energy. Mr. Sullivan’s career began at Anderson Consulting. He earned a Bachelor of Science in finance from the University of South Alabama and a Master of Business Administration from Baylor University. Click here to learn more about Champion’s leadership team.