chapter  9
30 Pages

Biomass Gasi—cation for Second-Generation Fuel Production

Nowadays, fossil fuels such as coal, oil, and natural gas are used for generating 80% of the energy proportion in the world. The use of the fossil resources in the energy production processes gives rise to an amount of carbon dioxide emission amount equal to the carbon transformed in the processes. So there is keen interest in reducing the CO2 emissions either modifying the ef—ciency of the processes using fossil fuels or using renewable resources, such as biofuels for which the carbon dioxide generated in the combustion is not considered to give any net contribution to the CO2 emissions in the atmosphere, since the carbon of the biomasses is originated from the CO2 transformed by photosynthesis [1,2]. The use of biofuels for power generation is limited even if, recently, several plants have been built based on conventional technology, that is, a boiler plant and a steam turbine cycle. A number of large plants have been built especially in the northern countries where the heat can be ef—ciently used for heating system acting for large part of the year. On the other hand, smaller combined heat and powers (CHP) plants have been built in recent years at any latitude based on

9.1 Introduction .......................................................................................................................... 213 9.2 Biomass Feedstock ............................................................................................................... 216 9.3 Pretreatment of the Feedstock .............................................................................................. 217 9.4 Gasi—cation ........................................................................................................................... 218

9.4.1 Gasi—cation Reactors and Processes ........................................................................ 219 9.5 Gas Clean Up ........................................................................................................................ 223 9.6 Gas Upgrading by Reforming ...............................................................................................226 9.7 Downstream of the Reformer: Water Gas Shift Unit ........................................................... 229 9.8 Fischer-Tropsch Synthesis of Middle Distillate ...................................................................230 9.9 Synthesis of Methanol and Dimethyl Ether .......................................................................... 232

9.9.1 Synthesis of Dimethyl Ether ..................................................................................... 233 9.9.2 From Methanol to Gasoline ......................................................................................234 9.9.3 From Methanol to Ole—ns .........................................................................................234