Synthesis gas, known as syngas, is a mixture of hydrogen and carbon monoxide along with other gases. Syngas is an important feedstock for the production of various chemicals and fuels such as ammonia, methanol, dimethyl ether, and Fischer-Tropsch (F-T) liquid fuels. Typically, syngas is produced from the reforming of natural gas. Several mature processes, such as steam methane reforming (SMR), partial oxidation (POX), dry reforming of methane (DR) and autothermal reforming (ATR), are used to produce syngas. A promising alternative to natural gas is biogas (mostly methane and carbon dioxide) which may be used as a feedstock for syngas production. There are some advantages of using biogas as the feedstock: (1) Biogas is considered to be a renewable energy source, which can be produced from several sources of biomass wastes, and (2) Biogas can reduce greenhouse effect by utilizing CO2 generated from the waste material gasification process and by mitigating the emission of methane.
In order to investigate the economic viability in using biogas for syngas production, fixed and operating cost issues as well as environmental impact must be considered and compared with the use of natural gas.
The thesis investigates the use of biogas for the production of syngas. The separation and reforming units are modeled. The extent of carbon dioxide and methane utilization is assessed. Carbon footprint is included in the objective function. A case study for producing syngas with a ratio H2/CO=1.5 is analyzed and a sensitivity analysis on natural gas price is evaluated to show the feasibility of using biogas instead of natural gas. The final result shows that in the recent past 20 years, 1/4 of the time favors biogas over natural gas as the feedstock. In other words, biogas is a suitable substitution for natural gas, especially when the natural gas price is higher than about $6.3/MMBtu.
