Advanced Coal Gasification System
DOE Phase II Contract DE-FG02-05ER84200
The efficient, clean, and cost effective conversion of coal is a principal goal of the U.S. energy industry and the DOE. Though it is still costly, coal gasification is currently the most effective method of conversion of the raw feedstock into syngas for liquid fuel production, hydrogen for fuel cells, or combustion in a gas turbine generator. Owing to high operating temperature and pressure and, in some instances, use of an oxygen blast (which requires an air separation unit), gasification is highly capital intensive.
A technology which involves the integration of fluidized bed gasification with chemical looping for the direct partial oxidation of coal is being developed to allow its gasification under less severe conditions. The technology eliminates cryogenic air separation and enables CO2 sequestration. This will reduce capital costs by 20% or more.
Phase I consisted of the identification of oxygen carrier materials and the demonstration of integrated air separation and coal gasification in chemical looping. All Phase I goals were met. Preferred catalyst materials were not only extremely inexpensive, but showed oxygen storage capacity as high as 30 wt% and proved to be rugged even with minimal processing. Incorporation into a fluidized bed reactor resulted in a gasification system capable of >98% carbon conversion and cold gas efficiency >70% at a bed temperature <850°C, easily exceeding the performance of other fluidized bed gasification processes while enabling CO2 sequestration.
Phase II will consist of the final selection and development of catalyst materials; design, fabrication, and testing of a pilot scale chemical looping system; and employment of the system in chemical looping coal gasification and other potential applications. Achievement of >98% carbon conversion and cold gas efficiency consistently greater than 80% will be Phase II objectives.
The capital savings from elimination of the air separation unit will reduce plant cost by a significant amount (~20%). This will make the technology attractive in combined cycle, hydrogen production, coal-to-liquids, commodity chemical production, and other applications.
Chemical looping is a novel means of gasifying coal which will reduce the cost of a FutureGen power plant by 20%. These plants will then be cost-competitive with traditional power plants but with minimal emissions, including CO2.