UC Riverside

This thesis is aimed at the process development, design, modeling and optimization of synthetic fuels, power and Substitute Natural Gas (SNG) production from coal and biomass with economic analysis based on steam hydrogasification technology. The steam hydrogasification is a thermochemical process to convert carbonaceous materials into methane-rich gas in the Steam Hydrogasification Reactor (SHR) at high hydrogen and steam environment. The methane could be either converted into syngas in the Steam Methane Reformer (SMR) for synthetic fuels production or used as SNG after going through the Water Gas Shift (WGS) reactor.

Optimum operation conditions for the SHR are determined based on mass and heat balance analysis derived from the Aspen Plus simulation results as well as data collected from experiments. Facilities utilizing bituminous coal and biomass green waste for coproduction of synthetic fuels and electricity are designed in detail. Cases with design capacity of 4,000 TPD (coal, dry basis) and 2,000 TPD (green waste, dry basis) are investigated with process modeling and cost estimation. The plant performance and capital cost is used as major inputs in the power financial model for process economics evaluation. The analysis shows that the coal plant with 90% Carbon Capture and Storage (CCS) using a cobalt catalyst in Fischer Tropsch synthesis is expected to produce 8,548 barrels fuels per day with production cost of 2.07 $/gal diesel equivalent at 12% Internal Rate of Return (IRR) and 54 $/MWh electricity sale price. The biomass plant is expected to produce 2,430 barrels fuels per day with production cost ranging from 1.55 $/gallon to 3.65 $/gallon diesel equivalent. The green waste and biosolid-to-SNG plant is expected to produce 19,848 MMBTU SNG per day with production cost ranging from 2.53 $/MMBTU to 15.23 $/MMBTU.

The process simulation and economic analysis presented here demonstrate that the steam hydrogasification technology could potentially provide an effective pathway to convert coal and biomass to fuels with high conversion efficiency and less capital cost. The steam hydrogasification process appears to be suitable for commercialization in large scales with a coal feedstock and also in a distributed network of small scale facility utilizing localized renewable feedstocks.

Financial incentives such as tax incentives, waste tipping fee, and other mechanisms are significant parameters in addressing the economic and market challenges of biomass derived fuels. Prospective commercial economics benefits with increasing plant size and improvements from large-scale demonstration efforts on steam hydrogasification.