Report: Up to 59 GW of Coal Units Are “Ripe for Retirement”

Between 153 and 353 coal generation units in 31 states—a total capacity of between 16.4 GW and 59 GW—are less economical to operate than natural gas plants and may be "ripe for retirement," a study from the Union of Concerned Scientists (USC) suggests.

The USC is a self-described "science-based nonprofit" that began as a collaboration between students and faculty members at the Massachusetts Institute of Technology and whose membership of "citizens and scientists" has grown to 400,000. Its study, Ripe for Retirement: The Case for Closing America’s Costliest Coal Plants, the group evaluates the economic viability of coal-fired power generation units in the U.S. and concludes that "there are many more un-competitive coal generators that should be considered for closure."

To evaluate the economic competitiveness of coal generators, the USC compared the cost of electricity from individual coal-fired electricity generating units with the cost of electricity generated from an average natural gas power plant. The organization deemed a coal-fired unit "ripe for retirement" if it was, after installing any required pollution controls, found to be more expensive to operate than an average natural gas combined cycle (NGCC) unit.

"Many older NGCC plants have already largely paid off their capital costs, whereas other newer plants are still recovering their initial investment. Thus, we calculated a range for the total capacity of coal generation considered ripe for retirement," the report says. "The high end of that range was defined by comparing the operating costs of a coal generator—assuming it was upgraded with modern pollution controls—to the operating costs of a typical existing NGCC plant whose capital costs were already largely recovered."

The low end of the report’s range was defined by comparing the operating costs of a coal generator already upgraded with modern pollution controls with the operating costs of a typical new NGCC plant whose capital costs were not yet recovered.

About 153 units in the low range and 353 in the high range of the nation’s total of 1,169 coal units were deemed "ripe for retirement." These units, representing between 16.4 GW and 59.0 GW of generating capacity, supplied 1.7% to 6.3% of total U.S. electricity consumed in 2009. Separately, about 288 units (about 41.2 GW) have already been scheduled for closure, the report notes.

It also claims that the "ripe-for-retirement generators can be closed without jeopardizing the reliability of the national electricity system because the United States is projected to have 145 GW of excess capacity by 2014 above and beyond reserve."

Among other key findings in the report is that the states with the most "ripe-for-retirement generators" are in the Southeast and Midwest, with the top five in order being:  Georgia, Alabama, Tennessee, Florida, and Michigan. These are owned mostly by Southern Co., the Tennessee Valley Authority, Duke Energy, American Electric Power Company, and First Energy.

Sources: POWERnews, USC

—Sonal Patel, Senior Writer (@POWERmagazine)