A blueprint for better efficiency and lower emissions from coal-fired power generation

4 December 2012

The Isogo power plant in Japan features a 600-MW ultrasupercritical coal-fired unit. Photo courtesy of J-POWER, all rights reserved.

Coal is the largest source of power globally, and its wide availability and relatively low cost mean it will stay so for the foreseeable future. A new International Energy Agency roadmap released today describes the steps necessary to adopt and further develop technologies that improve coal plants’ efficiency to produce more power while emitting less carbon.

“Zero-carbon power technologies like wind and solar will not decarbonise the power sector overnight, but the technologies exist to make coal power plants much more effective and cleaner-burning,” IEA Executive Director Maria van der Hoeven said at the Moscow launch of the English- and Russian-language versions of Technology Roadmap: High-Efficiency Low-Emissions Coal-Fired Power Generation. “The average efficiency of existing coal-fired capacity is only about 33%. This latest in a series of roadmaps on low-carbon energy technologies outlines a strategy to increase this by 4 percentage points in the next 10 years. If all coal plants in operation in 2010 were upgraded to this level, almost 350 million tonnes of coal per year could be saved, or 11% less than 2010 levels.”

High-Efficiency Low-Emissions (HELE) technologies already offer as much as 45% efficiency, and new technologies promise even higher rates. But about three-quarters of current operating units use less efficient technologies and more than half of current capacity is over 25 years old. Technology Roadmap: High-Efficiency Low-Emissions Coal-Fired Power Generation calls for replacing or retrofitting those plants with at least supercritical technologies. At very high temperature and pressure, steam enters a supercritical phase which is neither liquid nor gas but has the properties of both, so a supercritical plant no longer needs to separate steam from liquid water, improving efficiency. Ultra-supercritical and advanced ultra-supercritical technologies operate at even greater temperature and pressures, with the latter aiming to top 50 percent efficiency.

Such technologies’ reduced coal use helps offset the cost of the alloys and welding techniques they require, and improves energy security by extending supply and reducing imports. But only about half of all new coal-fired plants built in 2011 used HELE technologies, and much of current capacity is made up of units of less than 300 MW, too small to benefit from any of the improved technologies.

Combined with carbon capture and storage (CCS), HELE technologies also can cut global average CO2 emissions from coal plants by as much as 90 percent, to less than 100 grams per kilowatt-hour. That is crucial for the power sector to achieve the greenhouse-gas limits necessary to hold average global temperature rise to the target of 2 degrees, as stipulated in the IEA technology flagship publication Energy Technology Perspectives 2012. HELE technologies are essential to offset some of the associated costs of CCS.

The HELE roadmap shows governments and companies how to address other environmental concerns as well. New technologies that reduce emissions of local pollutants improve the sustainability of coal in power generation. And HELE technologies use less water in coal plants, an important development given growing concerns about current and future water availability.

Technology Roadmaps: High Efficiency, Low Emissions Coal-Fired Power Generation, now available in English and Russian and with a Chinese version planned, is the latest in a series of IEA publications that focus on global low-carbon energy technologies, from biofuels to smart grids, and provide recommendations for governments and other stakeholders in four areas: policy and market design, sustainability and public acceptance, financial challenges, and technology development.