The U.S. saw the historic start of operations at its first ultrasupercritical coal-fired power plant last December as Southwestern Electric Power Co.’s (SWEPCO’s) 600-MW John W. Turk, Jr. Power Plant switched on in Arkansas. The much-watched $1.8 billion project operates above supercritical pressure and at advanced steam temperatures above 593C (1,100F), allowing it to employ a more efficient steam cycle that tamps down fuel consumption by 13% compared to a subcritical boiler—as well as reducing reagent consumption, solid waste, water use, and operating costs.
When construction of the Turk plant (Figure 1) on a 2,800-acre tract between Fulton and McNab in Hempstead County, Ark., began in November 2008, the project was hailed for embodying the future of American coal power. It also had its roots in past achievements of American coal units, as SWEPCO, an American Electric Power (AEP) subsidiary and 73% owner of the plant, notes.
|1. A young Turk. Southwestern Electric Power Co.’s (SWEPCO’s) 600-MW John W. Turk, Jr. Power Plant between Fulton and McNab in Hempstead County, Ark., began operating last December, making it the first ultrasupercritical pulverized coal plant in the U.S. Courtesy: SWEPCO|
Early supercritical units at AEP’s Philo Unit 6 in Ohio (the world’s first supercritical unit, which operated from 1957 to 1975) and Philadelphia Electric Eddystone Unit 1 had previously (and successfully) operated at ultrasupercritical levels, but due to the unavailability of metals that could tolerate these extreme temperatures, operation at those levels could not be sustained. But although improved materials are now readily available, no other ultrasupercritical coal plants are in the pipeline in the U.S. They are being shunned by power and engineering companies for the technology’s high costs and the environment of regulatory uncertainty surrounding coal.
And like other coal projects under way in the U.S., the Turk project’s progress was pocked by several mishaps, including legal challenges by environmental groups the Sierra Club, the National Audubon Society, and Audubon Arkansas. It even received bomb threats. The litigation played out in a high-profile public battle for nearly four years, until December 2011, when a key settlement was reached that required SWEPCO, among other things, to phase out a 528-MW coal-fired unit in Texas, build 400 MW of renewable power, and not build any new generating units at the Turk site (and within a 30-mile radius) as long as the Turk Plant is operational. The settlement cost SWEPCO $10 million, which it agreed to contribute to support land conservation and clean energy in Arkansas, as well as $2 million in attorney fee reimbursements to the environmental groups. SWEPCO also agreed, in return for a resolution of all environmentally based legal challenges, to combust only coal from the Powder River Basin in Wyoming or subbituminous coal with similar low-sulfur characteristics.
Turk may be unique in the U.S., but it is just one of dozens of new ultrasupercritical pulverized coal plants that have cropped up in recent years around the world. The International Energy Agency’s (IEA’s) December 2012–released “Technology Roadmap: High-Efficiency, Low-Emissions Coal-Fired Power Generation” report finds that in 2011, about 50% of new coal-fired power plants used mostly supercritical and ultrasupercritical coal units, a share that doubled in the past decade. Ultrasupercritical plants are already operational in Japan, South Korea, Italy, Germany, and China (Figure 2). China is notably spearheading the ultrasupercritical revolution: As of 2011, it had 116 GW of 600-MWe ultrasupercritical units and 39 GW of 1,000-MWe ultrasupercritical units in operation out of a total coal-fired fleet of 734 GW. (See also “China Leads the Global Race to Cleaner Coal” in our December 2012 issue.)
|2. Leading the world. The share of supercritical and ultrasupercritical capacity is highest in a handful of countries such as Japan and South Korea, where supercritical technology was adopted before 2000, the International Energy Agency says in a new report. Driven by fuel supply concerns and immense power needs, China’s share of supercritical and ultrasupercritical capacity and India’s share of supercritical capacity have also grown tremendously. Source: Technology Roadmap: High-Efficiency, Low-Emissions Coal-Fired Power Generation © OECD/IEA 2012, Figure 5, p.11|
The rest of the world, like the U.S., lags far behind: At least three-quarters of the world’s operating coal power units use subcritical technologies, and most are more than 25 years old and less than 300 MW, the agency noted. Despite the significant fuel efficiency gains afforded by supercritical and ultrasupercritical technologies, the technologies’ widespread adoption is constrained by growing water shortages, by a need for flexible generation to balance renewables, and by costs, the IEA says.
Nevertheless, advanced ultrasupercritical plants aren’t too far into the future, the agency speculates. Though progress is needed in development and deployment of advanced ultrasupercritical plants operating at 700C (1,292F) and above, most groups involved have announced plans to advance a full-scale demonstration within a decade (between 2020 and 2025). China and India have already started their own programs, funded by both the public and private sectors, the IEA notes.
—Sonal Patel is POWER’s senior writer.