The moving, or fixed, bed gasifiers, exemplified by the Lurgi dry ash gasifiers, are installed at both Sasol coal to liquids (CTL) plants and the Great Plains Synfuels Plant. When these plants were designed, the only commercial gasification process was Lurgi’s. Although fixed bed technology is 42% of the world’s total installed gasification capacity, the moving bed gasifier’s inherent limitations - relatively high maintenance costs, large capital investment to handle byproducts such as tars and ammonia, and relatively small throughput per foot of plot space - have stymied future installations.

The fluid bed gasifiers, such as the KBR transport reactor under development at the Wilsonville Power Systems Development Facility (PSDF), may be a viable alternative, especially for low rank coals. Although currently only 2% of the installed capacity, fluid bed gasifiers may have the potential to provide a compact IGCC-specific product line. It also appears to be a good solution for lower ranked coals. The scale-up issues with this technology will be explored in the Southern Company DOE-funded Orlando Project, scheduled for a 2011 startup.

The entrained bed gasifiers, licensed by ConocoPhillips, Future Energy, GE Energy, and Shell, are the current market leaders, with 56% of the installed base and the vast majority of all sales during the last 20 years. The reasons for the entrained bed gasifiers commercial dominance include: