Clean Coal

In 2013, coal accounted for 29 percent of the world’s energy supply. This figure is unlikely to change substantially in the near future because coal is ubiquitous, abundant and reliable, making it a secure energy source. Unfortunately, the combustion of coal produces more carbon dioxide (CO2) per unit of energy than any other fuel. Thus, CO2 emissions from coal-fired power plants are a significant contributor to the rising atmospheric CO2 levels that have been linked to global climate change. In an effort to mitigate anthropogenic CO2 emissions, particularly from coal-fired power plants, the Department of Energy initiated a carbon sequestration program in 1997 that continues to promote and sponsor the development of carbon capture utilization and storage (CCUS) technologies.

Oxy-coal for CCUS: Conventional air-fired coal combustion exhaust gases typically consist of more than 80 percent nitrogen (N2) along with carbon dioxide. To sequester that carbon dioxide, a pure stream of CO2 that can be effectively compressed must be generated. This avoids wasting the energy it would take to compress N2 and drastically reduces the volumetric requirements for storing the CO2. A pure stream of CO2 can be obtained by scrubbing the CO2 from the nitrogen-rich exhaust, or by separating the oxygen and nitrogen in air before combustion occurs and burning the fuel in a mixture of oxygen and recycled flue gases – a process called oxy-fuel combustion. While both the CO2 scrubbing and oxy-fuel technologies are considered viable and are being pursued at the research and pilot scales, techno-economic studies have indicated a preference for oxy-fuel combustion.

Modernizing coal technology for a healthier world: Here at the Laboratory for Advanced Combustion and Energy Research (LACER) we are studying oxy-combustion to understand how its combustion process differs from traditional combustion in air. We also are developing novel approaches to oxy-combustion that will increase plant efficiency and reduce costs.