Study Finds Existing Coal Fleet Is Vital for Meeting U.S. Power Needs
In late January, Secretary of Energy Ernest Moniz requested a study of existing U.S. coal-fired power plants to assess options for enhancing capacity, efficiency, and emissions profiles of the present generation fleet.
On May 14, the National Coal Council (NCC), an advisory group that provides recommendations to the Secretary of Energy on policy matters relating to coal and the coal industry, approved the completed study. In it, the NCC noted that extreme winter weather events in early 2014 had demonstrated the importance of the existing coal fleet as limited natural gas resources were diverted from electricity production to meet residential heating needs. During January and February 2014, over 90% of the increase in power demand (versus the same period in 2013) came from the existing coal fleet.
The main purpose of the report, though, was to consider technology that could be developed to help existing facilities meet future challenges. Three main categories were identified by the study. They included technology that could:
- Enable more flexible operation of units that will be cycling and undergoing more frequent startups and shutdowns.
- Reduce CO2 emissions.
- Reduce traditional gaseous, liquid, and solid waste streams.
The need for more flexible operation was based on changing market conditions within the electric generation industry. The study noted that many existing coal-fired power plants were designed as baseload units, but in the future, they may only operate at baseload during peak demand season, while cycling at other times. During periods of high demand, fleet resiliency could be negatively affected by the fact that about 20% of the existing coal-fired generating capacity is projected to retire by 2020.
The report recommended collaborative efforts in developing assessment tools, and improving sensors and controls. It also suggested research to enhance knowledge about operating flue gas desulfurization and selective catalytic reduction systems in cycling environments.
The study focused on efficiency to solve some emissions challenges. It conceded that there is no “one-size-fits-all package of solutions,” but suggested that several options exist for improving plant performance. Some examples presented in the study included: drying coal using waste heat, upgrading steam turbines with improved designs, reducing corrosion and deposition on heat transfer components, and increasing utilization of variable frequency drives on plant equipment.
While noting that systems to control particulate matter, NOx, and SO2 are already widely used, continuing development of new technologies for emissions reduction is still worthwhile. According to the report, for every dollar of federal funding in coal technology development, approximately $13 in benefit is accrued. Carbon capture and storage (CCS) is one such technology, but the report suggested that the time for retrofitting existing units is running out because less than 10% of the current fleet will be less than 40 years old in 2030. Retrofit decisions for capital-intensive projects such as CCS hinge on many factors, not the least of which is remaining useful life, so developing solutions sooner rather than later is important for the industry.
The NCC has prepared more than 30 studies for the secretary of energy in its 30-year history. The group is chartered under the Federal Advisory Committee Act and does not engage in lobbying activities. Jeff Wallace, vice president of fuel services for Southern Co. was council chair for the study, which resulted in the 107-page report that was approved by the NCC membership during its spring meeting.
—Aaron Larson, associate editor (@AaronL_Power, @POWERmagazine)