UC Santa Barbara Study Finds Over 100 US Coal Plants Lack Retirement Plans

A new study from the University of California, Santa Barbara (UCSB), published on October 27, 2025, explores how the U.S. can effectively retire its remaining coal-powered power plants to meet national climate goals. 

More than a hundred plants across the country still lack retirement plans. This could jeopardize the country’s net-zero targets, according to the research. The study was originally released in ‘Nature Energy’ 

About 105 gigawatts of coal capacity, across 114 plants, are projected to operate through 2035. The timeline is inconsistent for U.S. climate goals that call for a complete phaseout of coal by the same year. 

Coal is complex, and there is no single correct approach to deal with it, said Sidney Gathrid, the study’s lead author. 

“Our goal was to build tools that reflect that complexity, so different actors can take on different facets of the problem. There’s no one straightforward path, and we wanted to do research that represented that reality,” Gathrid said. 

Gathrid and his team collaborated with Grace C. Wu, an assistant professor in the Environmental Studies Program and the paper’s senior author. 

To achieve the goals, policymakers need to move beyond one-size-fits-all approaches and instead focus on the exact contexts that accelerate the retirement of coal plants, the research showed. 

The researchers developed a framework combining graph theory and topological data analysis to categorize the country’s coal fleet into eight groups based on 68 technical, economic, environmental, and socio-political factors. 

The researchers also introduced a “contextual retirement vulnerability” score that assessed each plant’s susceptibility to early retirement by comparing it with facilities that have already announced closures. 

The framework identifies “retirement archetypes” that explain patterns behind the retirements of other coal plants. These can range from regulatory and health-based reasons to challenging economic or political conditions. The retirement archetypes offer a clear understanding of levelers that can be applied to similar facilities across the country. 

“Instead of asking only why coal plants retire, we asked how we can make retirements happen faster — and in ways that are efficient and grounded in data,” Gathrid said. “Our framework helps policymakers and advocates identify where they can have the biggest impact.”

Gathrid began working on the study as his senior thesis in UCSB’s Environmental Studies Program, supported by the campus’s Manalis Leadership Fellowship, sponsored by Howard and Lisa Wenger. 

The project’s scope and impact are rare for undergraduate research, Wu said. 

“This is Ph.D.-level work. It’s extremely unusual for a project that started as a senior thesis to reach this level of sophistication and impact,” Wu said. 

The framework not only describes which plants might retire, but it also shows how to accelerate those retirements using drivers that worked successfully, Wu added.