Biomass gasification in fluidized beds: A review of biomass moisture content and operating pressure effects

The global dependence on fossil reserves as well as the environmental aspects related to them are some of the factors that propel research on renewable energy forms. Gasification, a thermochemical process that converts carbonaceous resources into syngas, is an advantageous alternative due to its relatively low costs, high efficiencies, and syngas' wide variety of applications. Although gasification is a very promising heat, power, and fuel production technique, there is still a field of improvement in gasification in fluidized beds when it comes to operation under high pressure and with feedstocks containing moderate or high moisture contents. Thus, to provide enough information to address such questions, the present work aims at bringing an overview of gasification concepts, as well as an in-depth discussion based on simulation, laboratory- and demonstration-scale works of the effects of biomass water content and pressure on different parameters of several fluidized bed gasifiers. Moreover, diverse strategies for handling high-moisture content biomass materials are presented, as well as the achievements and technical difficulties encountered by worldwide development and demonstration plant projects that designed and used pressurized fluidized-bed gasifiers.