ZECA A PATH TO ZERO-EMISSION COAL

Of the many possible solutions to emissions control, a concept being developed by the Zero Emission Coal Alliance is generating much interest within the power and coal industries. This group of nearly 20 Canadian and U.S. power companies, coal producers and government agencies is currently investigating a potentially highly efficient means of generating electricity while producing no emissions and permanently sequestering CO2. The research is based at the Los Alamos National Laboratory (www.lanl.gov/energy).

In the ZECA process, coal is gasified in hydrogen, a principle that dates back to the turn of the century. The process produces methane (CH4), which is reacted with calcium oxide (CaO) to make hydrogen and calcium carbonate (CaCO3), thus capturing carbon dioxide (CO2). The hydrogen is used to gasify the coal as well as to generate power in a high temperature fuel cell. Waste heat from the fuel cell then separates CO2 from the carbonate in a concentrated stream, allowing the calcium oxide to be re-used. Using calcium oxide allows CO2 to be captured in an energy neutral fashion, making the system potentially very efficient.

The concentrated CO2 stream is reacted with calcium or magnesium silicates to make carbonate rock, a naturally occurring process that is accelerated under pressure. In fact, the process produces energy and the end product is the stuff of the Rocky Mountains. This carbonation process can be used with any source of CO2. The CO2 is permanently sequestered in a natural and benign product. Moreover, the Olivine and Serpentine rocks that contain the required silicates are found extensively around the world, and more than enough exist to handle all sequestration needs from all fossil fuel sources.

Courtesy of Los Alamos National Laboratory