Potential impacts of 316(b) regulatory controls: on economics,electricity reliability,and the environment

Nearly half of the utility-owned steam electric generating capacity in the United States is cooled by once-through cooling systems. These plants withdraw cooling water primarily from surface water bodies. Section 316(b) of the Clean Water Act requires that the location, design, construction, and capacity of cooling water intake structures reflect the best technology available (BTA) for minimizing adverse environmental impacts. At present, the US Environmental Protection Agency (EPA) has not yet promulgated implementing regulations governing intake structures; however, the agency is required by a Consent Decree to develop such regulations. EPA has introduced several draft tiered regulatory framework approaches that, depending on site-specific factors, may impose various regulatory burdens on affected utilities. Potential new requirements could range from compiling and submitting existing data to demonstrate that existing conditions at each unit represent BTA to retrofitting plants with closed-cycle cooling systems (primarily cooling towers). If the final regulations require installation of cooling towers or implementation of other costly plant modifications, utilities may elect to close some generating units rather than invest the funds necessary to upgrade them to meet the Section 316(b) requirements. Potentially, some regions of the country may then have a higher proportion of closed units than others. This may raise concerns over the reliability of electricity supply in those regions. If a significant number of plants are converted from once-through cooling systems to cooling towers, the environment will face secondary adverse impacts, such as additional fuel usage, air emissions, and water evaporation, and utilities will need to construct additional generating capacity. This paper describes a study that Argonne National Laboratory had proposed to conduct for the US Department of Energy to explore some of the potential outcomes of EPA’s Section 316(b) regulatory process and associated effects on economics, electricity supply reliability, and the environment.