EPRI Targets Thermal Optimization, Emissions Controls to Enhance Turbine Fleet

With the energy transition unfolding in real time, turbine-powered thermal plants are increasingly relied upon to deliver flexible, affordable, and clean electricity; however, this demand presents several complex and nuanced challenges that require holistic programs to integrate heat rate and flexibility. EPRI’s Stephen Storm, Program Area Manager – Thermal Optimization and Emissions Controls, offered a detailed and comprehensive strategy to manage thermal plants as the aforementioned energy transformation takes place.

TURBO: Why are flexibility and heat rate such important drivers for thermal plants and the overall energy transition?

Storm: As the energy transformation accelerates, generation fleets are increasingly challenged to deliver increased flexibility and efficiency while maintaining reliability, affordability, safety, and clean electricity production. The continued demand for thermal capacity in a low-carbon energy future—one with greater variable energy and competition across the grid—underscores the need for enhanced operational capabilities from existing and emerging assets. The optimal solution for any fleet is dependent on a complex interplay of the existing generation fleet assets, the market drivers, and the direction of regulatory policy where the fleets operate.

The efforts behind improving heat rate and flexibility require a broad understanding of power plant design, operation, maintenance, ambient conditions, thermal-hydraulics, combustion, plant processes, measurement techniques, controls, materials, and fuel types. To be successful, a holistic approach must be taken to drive the results of any action towards cost effective, known, and acceptable effects on the overall plant. This demands a systematic and programmatic approach to how heat rate and flexibility are being managed.

TURBO: What are some challenges associated with improving heat rate and flexibility?

Storm: Rising operating costs, increased competition from other non-thermal power generating sources, and regulatory pressures have increased the need to improve heat rate and flexibility. Heat rate improvements have a direct relationship to total releases of all air emissions, including CO₂. Flexibility has a direct relationship with the ability to integrate additional variable energy resources. The integration of heat rate and flexibility assessment capabilities to evaluate physical and operational changes is critical for optimizing operating, maintenance, and investment strategies.

TURBO: How does EPRI support this transforming energy system? What are some of EPRI’s cost-effective tools and proactive approaches?

Storm: EPRI has developed, demonstrated, and advanced heat rate and flexibility improvements via new technologies, hardware, software, and cost-effective operating/programmatic practices for enhancing efficiency, flexibility, and maximum reliability in fossil power plants. In addition, the institute has identified and quantified effective solutions for operation along with performance issues associated with adverse effects of these improvements on baseload and flexible operations, heat rate, and fuel quality. This program area continues to make advances in these fields and others.

TURBO: As more renewables come online, how will thermal plants make the shift from baseload operation to a balancing role?

Storm: For several years, EPRI has been deeply involved in research on flexible operations and its impacts, principally through EPRI’s Operational Flexibility Case Studies, Operational Readiness Guidelines, and the Changing Mission Profiles pilot program, and Mission Profiles Working Group. Through these activities, EPRI has developed a substantial amount of knowledge from subject matter experts at coal and gas units experiencing different modes of flexible operations.

Through this research and collaboration with the power industry, EPRI has built out a comprehensive and systematic flexibility assessment process, as well as tools for managing risk, vulnerability, and cost. This research has encompassed equipment damage effects, operations and maintenance impacts and strategies, and asset management critical for managing supply vs. demand needs from thermal generating assets.

TURBO: What has EPRI’s latest research discovered regarding thermal optimization and emissions control? How will these lessons be applied in the power generation space?

Storm: The program's R&D initiative for 2026 is to expand and improve upon holistic approaches developed for heat rate and flexibility enhancements into an overall framework for fleet optimization. This aims to improve the delivery of generation with the power plant heat rate independent of the fuel fired, and to enhance the delivery of flexibility across thermal generating plants.

Some specific efforts and recent projects include:

• Cycle Isolation Guideline Update
• Review alternate way of measuring flow leaking through a cycle isolation valve using temperature measurement, determining if repair or replacement of a cycle isolation valve is justified.
• Combined Cycle Performance Monitoring and Recovery. This research is intended to provide the latest information on combined cycle thermal performance monitoring, assessment, recovery, and optimization. This will help identify performance degradation on all parts of a unit using key performance indicators, identify performance recovery activities, quantify performance, and support future performance monitoring.
• Cooling Technology Design, Specification and Operations Guidance

Steam turbine bypass valves have been identified as an area of concern for most steam plants. Plants that start and stop often have had many issues. There’s concern over the negative performance impact these valves can have on operations, as well as the control issues and the high-energy pipe damage that has occurred to these systems. Logic control problems, pipe quenching and subsequent catastrophic high-energy piping failures, condenser damage, and more have all been identified as actual problems. Inconsistencies have been identified with regards to control logics even for similar plants.

Installation criteria have been identified as concerns; however, additional research is needed to develop design standards and model improvements. To support this, we intend to expand our list of bypass valve case studies, run simulations, and propose solutions. Going forward, this research intends to provide deeper analysis of existing and recommended logics; address what is occurring in past case studies; and develop recommended new plant design criteria to address case study issues.

TURBO: Outside of thermal and emissions research, what else can EPRI discuss about upcoming projects and/or exciting new research initiatives?

Storm: Generation Fleet Optimization demands a holistic approach to optimize power plant flexibility, efficiency, and emissions intensity, without creating adverse effects on power plant equipment and operation downstream or leading to sub-optimization of the overall generating fleet. Some other mentions include the Thermal Optimization and Emissions Controls Area, Bi-Annual 2026 Heat Rate Conference, Heat Rate Awareness Training, Cooling Tower Event, and many more.