Turn Down for What? The Economic Value of Operational Flexibility in Electricity Markets

This paper explores how enhanced flexibility through lower minimum load levels (also called "turndown" limits) for coal- and natural-gas-fired power plants can impact operations and profitability. Using soft-linked capacity planning and unit commitment models, this research examines the economic value of this flexibility and variation across different regions, generation asset types, and market environments (e.g., level of renewable deployment). Model results suggest that lower minimum loads are most valuable for mid-merit units with intermediate capacity factors, policy conditions that rearrange the merit order (e.g., carbon pricing), regions and scenarios without seasonal layup of assets, and units that are more flexible than generators with otherwise similar characteristics. Lower minimum loads can increase operating hours, increase net revenues, and decrease startups and long-run maintenance costs. The scenarios in this analysis show that plant flexibility affects operations more than annual profitability, which may have a higher system value for integrating renewables than a private value for the flexible unit. For many plants, the modest changes in net revenues with lower minimums mean that the focus will likely be on making operational modifications to increase flexibility rather than on capital investments. Additionally, this analysis quantifies how revenues from ancillary services markets can boost the value of lower minimum loads, especially for efficient natural gas units, but total market size and depth are uncertain.