Fossil fuels are the world's primary energy source and account for more than 60% of the electricity generated in the United States. Fossil-fueled power plants provide stability and reliability to the operation of the U.S. power grid. A recent report from the International Energy Agency (IEA) indicates that coal will continue to be the largest source of electricity production in the world by 2040. The U.S. Department of Energy is committed to improving the efficiency, reliability, and performance of the current U.S. coal fleet of fossil-fueled power plants simultaneously addressing flexibility and stability due to renewable penetration, while also advancing technologies that will underpin the coal-fired power plant of the future.
The average coal-fired power plant in the United States operates near 33% efficiency. The Transformative Power Systems Research Program aims to increase the efficiency of existing plants by 5% by 2023 and for new plants by 2027. This will be accomplished by improving the underlying technologies, components, systems, and operations that would incorporate novel sensors and artificial intelligence (AI) technologies within existing plants.
The program focus will be on early-stage R&D on advanced technology, such as topping cycles, advanced high temperature/pressure materials, control systems with dynamic data analysis for early component failures, that the industry could utilize in existing facilities to improve the plants’ performance, efficiency, and flexibility. The program is also focusing on developing small, flexible, zero or near emissions coal plant of the future to produce power at over 40% efficiency with load following (>4%/min) and reduced startup time. The innovative power generation concepts that are on the verge of requiring novel system integration and 50-350 MW scale demonstration could result in overall efficiency close to 45% for coal-fired power plants.
Technology Improvements for Existing Power Plants
Improvements to turbines, boilers, and other critical components offer opportunities for enhancing plant efficiency, reliability, flexibility, and stability. The DOE is supporting R&D investments in a number of areas, including increasing power plant operating temperatures while quantifying the system wide impacts, increasing steam temperature and pressure for higher thermal efficiency, sliding pressure upgrade, condenser material improvement, air heater seals, thermal storage, sensors to detect early failures, and digital monitoring with AI base analyses. The co-ordination of these efforts are to be integrated at number of units which could also improve the dispatch of these coal units in existing and future market conditions by making more efficient and reliable at all loads.
To achieve the greatest improvements, all plant upgrades and component improvements need to coordinated and optimized. To this end, DOE is supporting research in data and analytics, modeling and analysis, performance monitoring, and system design optimization. There is a renewed focus on instrumentation that could withstand severe conditions and provide valuable input for effective boiler and turbine operations. The artificial intelligence based on predictive maintenance of individual components such as turbine and fan blades, boiler tube failures, condenser cleanliness, and air-heater leakages would help in lowering the cost of operation. Currently, DOE is supporting over 40 projects related to existing coal plant efficiency, stability, and flexibility improvement.
Coal Power Plants of the Future
Changes to the U.S. electricity industry are creating a paradigm shift in how the nation’s generating assets are operated. The need for considerable dispatchable generation, critical ancillary services, grid reliability and energy security concerns, combined with potentially higher future natural gas prices, creates the opportunity for advanced coal-fired generation for both domestic and international deployment. Deployment of new coal plants will require a different way of thinking, and advances beyond today’s utility-scale power plant concepts (e.g. base-load units) and state-of-the-art technologies as well as innovative approaches to design and construction. DOE’s Transformative Power Generation program aims to advance R&D in these technology areas to achieve, in partnership with industry, a pilot-scale power plant with these advanced approaches. Specifically, DOE envisions that the future coal fleet may be based on electricity generating units possessing many of the traits below:
- High overall plant efficiency (40%+ HHV or higher at full load, with minimal reductions in efficiency over the required generation range without carbon capture).
- Modular (unit sizes of approximately 50 to 350 MW), maximizing the benefits of high-quality, low-cost shop fabrication to minimize field construction costs and project cycle time
- Zero or near-zero emissions, with carbon capture system integrated into the plant
- The overall plant must be capable of high ramp rates (>4%/min) and low load (<20%)
- Minimized water consumption
- Reduced design, construction, and commissioning schedules from conventional norms by leveraging techniques including but not limited to advanced process engineering and parametric design methods
- Enhanced maintenance features including technology advances with monitoring and diagnostics to reduce maintenance and minimize forced outages
- Integration with coal upgrading, or other plant value streams (e.g., co-production)
- Co-firing natural gas and up to 20% biomass