Mark Stover serves as the Executive Director of TSSA. He joined the association in May 2024. Prior to joining TSSA, Mark served on the association’s board of directors and was its secretary.

Before TSSA, Mark led government and regulatory affairs activities in ERCOT and SPP for Apex Clean Energy, a national leader in utility-scale wind, solar, BESS, and green hydrogen development, construction, and operations.

Mark holds over 25 years of external affairs experience in the electric power industry. Prior to joining Apex in 2017, he ran a consulting practice focused on renewable energy policy and project development. From 2008-2014, Mark served on the management team of a privately funded renewable energy company, Hydro Green Energy (HGE), where he was Vice President of Corporate Affairs. From 2006-2008, Mark worked at Good Company Associates in Austin, TX, where he provided a variety of consulting services to clients in the renewable energy, demand response, and energy efficiency sectors.

Mark’s career began in 1994 in Washington, DC, where he spent 11 years working at three national trade associations, including the Electric Power Supply Association (EPSA) and the National Hydropower Association (NHA), where he ran legislative, regulatory, and media activities. Mark graduated from Syracuse University, where he studied political science and foreign affairs. He left DC for Austin in 2005.

Timothy Harvey has more than 30 years of experience in the energy industry, including 18 years in Austin Energy’s solar group. Under his leadership, Austin Energy has developed and expanded its award-winning residential, multifamily, and commercial rebate programs, as well as GreenChoice, Community Solar, and Shared Solar programs. Harvey is dedicated to advancing renewable energy solutions that benefit the Austin community and support the city’s sustainability goals.

Austin Energy is a leader in renewable energy, pioneering Texas' wind and solar industries. As a community-owned utility, it prioritizes customers over shareholders, ensuring its programs align with local sustainability and resiliency goals while keeping costs fair and transparent.

Christian Claudel is an Assistant Professor of Civil, Architectural and Environmental Engineering at UT-Austin. He received the PhD degree in Electrical Engineering from UC-Berkeley in 2010, and the MS degree in Plasma Physics from Ecole Normale Superieure de Lyon in 2004. He received the Leon Chua Award from UC-Berkeley in 2010 for his work on the Mobile Millennium traffic monitoring system. His research interests include control and estimation of distributed parameter systems, wireless sensor networks and unmanned aerial vehicles.

Etienne Cadestin is the founder of Longevity Partners. He also founded Longevity Power, a subsidiary of the Longevity Partners Group focusing on the deployment of rooftop solar and energy storage. Prior to that, Etienne worked at Knight Frank, and the United Nations Environment Programme. He has more than fifteen years of expertise in sustainability and responsible investment. Over that period, Etienne has been advising some of the largest institutional investors on their future proofing and value creation strategies and Longevity Partners was one of the fastest growing privately owned sustainability advisory businesses in the world. Etienne stepped down as the group global CEO in October 2025 and is focusing on  senior advisory and high impact innovative initiatives. 

Sergio Castellanos is an assistant professor at the UT Austin's Civil, Architectural, and Environmental Engineering Department, where he leads the RESET (Rapid, Equitable & Sustainable Energy Transitions) Lab, analyzing just decarbonization pathways for emerging economies, data-driven sustainable transportation approaches, and equitable local energy transitions.  With collaborators, his interdisciplinary projects have been awarded international prizes (United Nations' Data for Climate Action Challenge), won national competitions (México), and gathered media attention (Forbes, Greentech Media). He was a recipient of the 2023 Cesar Chavez "Si Se Puede" Award' from PODER, an environmental justice organization in East Austin, TX, in recognition of his leadership and transformative work to help better communities in Austin. Sergio holds an Engineering Ph.D. from MIT.

Greg Gosnell is the President and Chief Executive Officer of GenH2, a leading company in hydrogen infrastructure technology. Greg is an accomplished leader with a proven track record of driving strategic growth in the emerging technologies and clean energy sectors. With deep expertise in scaling businesses, forging strategic partnerships, and driving innovation, Greg has successfully led multiple organizations through transformative growth. Under his stewardship, GenH2 has achieved significant advances in development and commercialization of liquid hydrogen technologies, positioning the company as a key player in the transition to a clean energy future. Greg has spearheaded initiatives to accelerate market expansion, increase revenue, and enhance operational efficiency, positioning GenH2 for long-term success in a dynamic global market. Greg holds degrees in Geophysics and Mathematics from Colorado State University Pueblo.