Renewable Natural Gas (RNG) has been identified as an important alternative fuel that can help to achieve a number of national goals related to the reduction of fossil fuels and to the reduction in carbon dioxide emission. RNG can be produced from various carbonaceous materials such as biomass and organic wastes via a gasification process. The CE-CERT steam hydrogasification technology combines hydrogen with steam under pressurized conditions to convert a wet feedstock to a methane enriched syngas which can be upgraded to RNG and used for electric power and as an alternative transportation fuel.

The main objective of this thesis is to develop a new process configuration of the steam hydrogasifier (SHR) using a water gas shift (WGS) reactor for the increased production of RNG in an economical manner. The producer gas from the SHR consists of H₂, CH₄, CO, CO₂ and steam. The WGS process converts CO using the existing steam in the product stream from the SHR to H₂ and CO₂. This results in a self-sustainable internal source of hydrogen that can be generated internally and of sufficient quantity to be recycled back to the SHR. In this study, a mixture gas comparable to the composition of the producer gas from the SHR when using biosolids comingled with green waste was used as the input gas to the WGS reactor. A lab-scale WGS reaction system using a commercially available high temperature shift (HTS) catalyst was designed and built. The influence of temperature, space velocity, gas composition and particle size of catalysts on the conversion of CO using this system was investigated. It was found that at optimum conditions approximately 65% of the CO can be converted using the HTS catalyst operating at 350^oC and atmospheric pressure. The hydrogen produced at this condition was sufficient to be recycled back to the SHR. Also, the overall change of CH₄ production was negligible.

A mixture gas containing a wide range of H₂S was carried out in the shift reactor using a Sour Gas Shift (SGS) catalyst to determine the influence of sulfur impurities. The conversion of the mixture gas with 350ppm of sulfur was 55% at the reaction temperature of 450^oC and a space velocity of 2500h^-1, compared to 65% with no sulfur. The percent conversion of CO could be improved if the composition of CO₂ was decreased.

A larger scale HTS reactor was designed and built using the data from the experiments mentioned above. This was integrated into a bench scale Process Demonstration Unit (PDU) of the SHR with a capacity of 0.1TPD of dry feed. This process configuration demonstrated the production of high levels of RNG based for the CE-CERT technology using co-mingled biosolids and woody biomass as the feedstock. The reaction temperature of the SHR and WGS reactor were set at 750^oC and 350^oC, respectively, with an operating pressure at 150psi. A carbon conversion of 42% for the SHR and CO conversion of 60% of WGS were achieved at those conditions. The final product gas contained over 85% of CH₄ after gas cleanup in which 85MJ/day or 32.6MJ/m³ of energy was produced. This result clearly shows the viability of the process and provides critical design information to upscale to a pilot facility in the near future.

The development of sustainable fuels from biomass has become important due to the depletion of fossil fuels and concerns of global climate change. Microalgae offer several advantages as sources for bioenergy; their rapid growth rate, high productivity and lipid content, ability to cultivate in places other than on farmlands, or arable land, and their ability to capture CO₂ from flue gas which can be used as a source for photosynthesis. Microalgae are able to produce a wide range of biofuels including biodiesel, methane, ethanol, hydrogen, and synthetic fuels using different conversion technologies. High energy requirements and the cost for dewatering/drying and extraction are major drawbacks. The steam hydrogasification (SHR) process is attractive as an alternative for the conversion of microalgae to biofuels because the SHR can handle wet microalgae biomass without drying or extraction and been shown to have high carbon conversion efficiencies.

The overall objective of this thesis is to investigate the feasibility of using whole microalgae directly (wet biomass) and/or using the microalgae residue after lipid extraction to produce low carbon sustainable fuel using the CE–CERT process. Steam hydrogasification can convert microalgae to a high energetic synthesis gas in the presence of steam and hydrogen. The carbon in the synthesis gas then can be converted to synthetic fuels and electricity.; The performance of steam hydrogasification of microalgae was investigated by varying parameters including gasification temperature, H₂/C and steam/biomass ratios. It was found that the operating conditions at a gasification temperature 750 °C, a steam/biomass ratio of 2 and H₂/C ratio of 1 could provide richer in methane production and high carbon conversion (65%) using microalgae as a feedstock. The hydrogen in the product gas was sufficient to maintain a self–sustained supply back to the SHR. One ton per day of microalgae biomass is expected to produce FT fuel of 1.06 barrel with an overall thermal efficiency of 27%.

The utilization of the microalgae residue from traditional transesterification and the effect of different lipid content of different microalgae using the steam hydrogasification process was investigated also. It was found that the SHR could use microalgae residue to reduce the algae waste and recover energy of about 4.9 MJ/kg dry microalgae residue. A higher lipid content would enhance the performance of the SHR in terms of carbon conversion and production of methane that resulted in more FT fuel.

Life cycle energy and greenhouse gas (GHG) emissions for the production of Fischer–Tropsch (FT) fuel derived from microalgae using the CE–CERT process were calculated and compared to microalgae to biodiesel production using transesterification. It was found that life cycle energy requirements for the microalgae biofuel production using CE–CERT process were significantly lower (about 50%) compared to the transesterification process. The life cycle analysis showed that the lowest energy consumption to be 1.96 MJ/MJ fuel (40 wt% of lipid content) compared to microalgae to biodiesel production. CE–CERT technology reduces the GHG emissions by 50–64% compared to production of conventional diesel fuel.

Liquid fuels produced via the steam hydrogasification of biomass feedstock followed by downstream gas to liquid processes appears to be a cost effective approach to replace fossil fuels, to decrease the dependence of imported oil and to decrease greenhouse gas emissions. A critical technical obstacle of using biomass feedstock effectively in many gasification processes, including steam hydrogasification, is the need to prepare a high carbon concentrated (i.e., high energy) slurry that can be introduced into a pressurized reactor in a cost effective and energy efficient manner. Conventional dry feeding systems, such as lock-hopper and pressurized pneumatic transport, are complex, unreliable, and operationally expensive. An extra carrier gas is needed in some instances or vibrators to avoid fluctuations in the quantity of feed introduced into the reactor. Slurry feeding is a simpler, reliable, and inexpensive method of transporting and pressurizing the feedstock into gasification reactors and has been demonstrated in commercial scale application using 100% coal. Biomass slurries have less energy density compared to coal and require high carbon content in order to be efficiently gasified. The hygroscopic and hydrophilic nature of biomass results in a significantly reduced amount of carbon in pumpable slurries. The main goal of this thesis was to develop, design, and implement a Hydro-Thermal Pretreatment (HTP) process that will result in a pumpable biomass slurry with high energy and carbon content for use in a commercial scale, pressurized steam hydrogasification reactor.

The first objective of this thesis was to design, build and evaluate the performance of a laboratory scale HTP process. Four carbonaceous feedstocks (coal-wood-water, wood-water, wood-biosolids and wood-manure) were hydrothermally treated using a procedure developed as part of this thesis. The viscosity, flow and energy content were determined under various experimental conditions including: particle size; initial composition of feedstocks (carbon/water ratio), thermal input (time and temperature of the heating process) and head space gas composition as a consequence of heating. The rheology properties and the settling velocities of the particles for the resultant slurries were evaluated before and after HTP. An empirical model was developed to simulate the rheology properties. The modeling work was necessary to assist with predicting flow behavior of the slurry for commercial applications. The carbon balance for the cumulative gas, liquid and solid phases of the feedstock slurry after HTP was analyzed to determine the carbon recovery in the slurries and found to be greater than 98% recovery. Finally, the heating value of pretreated wood particles was determined to estimate the energy recovery in the slurries which was also found to be in excess of 98%.

The second objective of this thesis focused on obtaining a better understanding of the chemical mechanism of the formation of the biomass slurry as a consequence of the HTP. Four mechanisms and analytical methods were utilized to assist in the explanation: 1. Surface charge alternation, zeta potentials of raw wood particle and pretreated wood particle were analyzed and compared; 2. Particle shrink, Scanning Electron Microscopy (SEM) comparison of wood particles before and after HTP were compared to visualize this effect of HTP; 3. Free bulk water release from biomass microstructure, both SEM observation and liquid-solid distribution of slurry were used to confirm porous site generation and free water release into bulk phase.

The third objective of this thesis focused on the design and scale up of HTP at the lab scale basis, a demonstration scale basis and a commercial scale basis. The lab scale and demonstration scale HTP process was designed and tested in our laboratory. Feedstocks production rates were targeted at 90g/hr and 8kg/hr on a wet basis for lab and demonstration scales. Mass and energy balance of both processes were performed based on experimental data. An ASPEN Plus simulation of a commercial scale HTP process was done using a production rate of 16,700kg/hr on a wet basis. Comparison of economy and energy efficiency was performed between biomass gasification with or without HTP process using the ASPEN Plus results.

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.

Energy security and climate change are two common challenges in the coming decades. The demand for energy is increasing. The CO2 in the atmosphere has increased to almost 400ppm, and it is mainly from energy usage. How to deal with energy-related CO2 emissions with the increasing demand for energy is becoming more crucial.

Carbon capture and sequestration during energy production is an efficient way to guarantee enough energy supply with a smaller carbon footprint. One unique technique is using in-situ CO2 capture technology, which uses a sorbent to capture CO2 directly in the reactor. CO2 is removed quickly as it forms by the sorbent, which can change the equilibrium to promote more energetic production. This technology has great potential to lower CO2 emissions and get higher energy production simultaneously.

A new concept of sorption enhanced steam hydrogasification reaction (SE-SHR) is the topic of this thesis. It combines sorption enhanced principles with the steam hydrogasification reaction (SHR). It was found that the addition of sorbent enhanced the CO2 removal and increased the production of H2 and CH4. Particularly, the amount of H2 was increased dramatically. It was found that the increase in H2 was enough to recycle when the CaO/C molar ratio was over 0.29. The sorption enhanced performance was also evaluated by varying other parameters including H2/C and Steam/C molar ratio, gasification temperature and sorbent particle size.

A study of the kinetics of the system showed that higher gasification temperature favored faster formation rates of CO2, CO and CH4 during both SHR and SE-SHR. The formation rates of CO2 and CO at 650°C, 700°C and 750°C were much lower during SE-SHR.

Several configurations based on SE-SHR for the production of Fischer Tropsch fuel and synthetic natural gas were developed and evaluated. The optimum gasification condition (H2/C-Steam/C) for Fischer Tropsch fuel production using SE-SHR based process was found to be 1.59-2.78. This process had lower total CO2 emissions with higher fuel yield compared to the optimum SHR based process. SE-SHR-Methanation based process for SNG production with the optimum gasification condition (H2/C-Steam/C) of 1.08-2.22 had the highest CH4% and near zero CO2% in the final gas product.

The gasification of biomass is potentially an efficient and economically viable technology to assist in reducing the global dependence on fossil fuels and carbon dioxide emission. CE-CERT steam hydrogasification technology combines hydrogen with water to convert carbonaceous matters to a high energetic synthesis gas which offers several advantages for biomass gasification compared to other mainstream gasification technologies. Although steam hydrogasification appears to be an advantageous gasification technology, it still needs to be improved for optimum efficiencies to assess the overall commercial viability. A particular challenge for the scaling-up steam hydrogasification process is the low reactivity of carbon with hydrogen. The gas residence time in the large-scale gasifier needs to be substantially long to account for the slow reaction rate in the presence of hydrogen. The consequence is that much larger size and more expensive gasifier is required to implement the large-scale CE-CERT process which leads to a considerably high initial investment cost. The main objective of this thesis is to investigate the effect of biosolids serving on the steam hydrogasification of biomass for improving the steam hydrogasification efficiency. The use of biosolids is motivated by its low cost, integrated in the steam gasification as the feedstock and the potential for catalytic effect due to its typically high concentration in iron and calcium. This research will not only contribute to technological analysis for the scaling-up CE-CERT steam hydrogasification process but also provide an alternative pathway for biosolids energy recovery in a cost-efficient manner.

Characteristics and kinetics of steam hydrogasification of biomass was investigated initially in chapter two with the objectives to optimize the reaction conditions and to establish a simplified approach for kinetic measurements in the steam hydrogasification. A newly designed laboratory-scale reactor, referred to as the inverted batch reactor is used in this thesis. This reactor succeeded performing the desired realistic thermal conditions to allow for fundamental laboratory studies of the steam hydrogasification. The heating rate and temperature were found to have significant influence on the steam hydrogasification. Kinetic parameters were obtained by using a first-order kinetic model based on product gas formation.

Steam hydrogasification of the co-mingled biosolids with biomass was investigated in chapter three to determine the effect of biosolids on the steam hydrogasification of biomass. It is experimentally demonstrated that the biosolids integrated in the feed dramatically improved the steam hydrogasification efficiency not only in carbon conversion but also in gasification reaction rate. The steam hydrogasification with 50wt% biosolids in the feed yielded more than 70% carbon conversion at 700oC. There was an approximately 6% increase in the carbon conversion compared to the steam hydrogasification of biomass. The gasification rates of CH4 and CO formation were enhanced by 18% and 12%, respectively. The characterization of metal elemental compositions in the biosolids revealed that the biosolids was particular rich in Fe, Ca.

Catalytic steam hydrogasification of biomass with different catalysts based on metal compounds of Fe, Ca, Mg, Na and K is investigated in chapter three. Steam hydrogasification of biomass with non-catalysts, with the in-situ biosolids and with the added catalysts were evaluated to identify the catalytic activity of biosolids. The catalytic activity of catalysts in the steam hydrogasification for CO formation followed the order of iron catalysts > biosolids > other tested catalysts. And the catalytic activity for CH4 formation was in the sequence of calcined dolomite > biosolids > other tested catalysts. Biosolids in-situ integrated in biomass feedstock was found to be highly active and effective to catalyze the steam hydrogasification and improve the steam hydrogasification efficiency. The catalytic action of biosolids on the steam hydrogasification may be attributed to the synergistic effect of iron, calcium and alkali metals in the biosolids.

The CE-CERT Steam Hydrogasification Technology efficiently converts carbonaceous materials to high energetic synthesis gas. This thesis investigates the direct production of gasoline range liquid hydrocarbons with high iso-paraffin content from synthesis gas. The goal is to provide a process to efficiently produce renewable gasoline that can be used directly without modification of engine or infrastructure.

An H-ZSM-5 shell Co/Al2O3 Fischer-Tropsch catalyst is prepared using a secondary-growth hydrothermal synthesis method. The catalyst not only synthesizes long-chain hydrocarbons from synthesis gas, but also cracks and isomerizes them into gasoline-range hydrocarbons with high iso-paraffin content. Characterization results show that the catalyst has good H-ZSM-5 shell coverage with no cracks or pinholes, with a shell thickness is around 4.29 μm. H-ZSM-5 shell composition is confirmed by EDX and XRD. In addition, the zeolite-shell catalyst has a 10% increase of surface area, compared to a conventional Fischer-Tropsch catalyst.

A high-temperature high-pressure lab-scale continuous Fischer-Tropsch reactor with LabVIEW automation system was designed and built. The reactor system has online gas and liquid sampling capabilities. It also has a PID controller with gain scheduling for precise heating control during Fischer-Tropsch synthesis test. Safety during reactor operation is ensured with alarms and automatic emergency response system.

Performance of a H-ZSM-5 shell Co/Al2O3 Fischer-Tropsch catalyst was investigated under various conditions. A maximum CO conversion of 97.1%, with a highest gasoline yield of 58% and iso-paraffin selectivity of 14.3%, was obtained. Sensitivity analysis shows that reaction temperature significantly affects CO conversion and iso-paraffin selectivity. Catalyst silicon to aluminum ratio also influences iso-paraffin selectivity, but has no effect on CO conversion. In addition, H-ZSM-5 shell Co/Al2O3 Fischer-Tropsch catalyst has much less carbon deposition than conventional catalyst, which can help reduce catalyst deactivation rate.

The steam hydrogasification reaction (SHR) refers to the thermochemical conversion of carbonaceous materials into synthetic gas in a steam and hydrogen environment. The formation of gaseous sulfur species from the solid sulfur in the feedstock is commonplace in thermochemical processes. It requires the cleaning of the output gas to protect the operation of downstream processes and catalysts. This thesis presents the results of an experimental study to determine the effect of temperature, steam and H2 partial pressure has on the distribution of the various gaseous sulfur species in the outlet gas of the SHR. Experiment results showed that sulfur in the feedstock is mainly converted to H2S in the SHR process. COS and CS2 were undetectable. The H2 and steam rich environment in the SHR process are favorable for the formation of H2S and suppress the COS and CS2 formation. An increase of H2S concentration was observed with the rise in temperature from 700oC to 800oC. An increase in the partial pressure of H2 decreased the H2S concentration released in the gas phase.

A lab-scale warm gas cleanup system was developed by using commercial ZnO sorbents based above results. A mixture gas simulated the composition of syngas from steam hydrogasification reaction was used as the feed gas. The effect of space velocity and gas composition on H2S breakthrough time was studied. It was found that H2S breakthrough time and sulfur capture capacity increased as the space velocity decreased. Moreover, addition of H2 or CH4 to the inlet gas stream has the positive effect on H2S breakthrough time. However, Addition of CO to the inlet gas stream decreased H2S breakthrough time. And addition of low content of CO2 to the inlet gas stream almost has no influence on H2S breakthrough time.

Techno-economic analysis was performed based on experimental and Aspen Plus simulation results in order to design warm gas cleanup system for CE-CERT process. Warm gas cleanup process by using regenerable sorbent is feasible for high capacity plant (syngas feed >=1000 tonne/day). And warm gas cleanup process by using disposable sorbent is more feasible for low capacity plant (syngas feed <1000 tonne/day). Economic sensitivity results showed that H2 availability and price is the most influential parameter affecting the cost for warm gas cleanup process by using regenerable sorbent, while ZnO sorbent price is the most influential parameters affecting the cost for warm gas cleanup process by using disposable sorbent.

In this report, the authors describe preliminary research dealing with vehicle emissions associated directly with 1) Automated Highway Systems ( AHS) and 2) ramp metering. In performing this analysis, a power-demand modal emissions model has been integrated with several transportation simulation models in order to quantitatively determine the effects of Intelligent Transportation Systems (ITS) technology on vehicle emissions. For AHS, a steady-state speed/emissions comparison has been conducted between vehicles that are platooned and non-platooned. A comparison has been made between a platoon under optimized and non-optimized CICC ( Coordinated Intelligent Cruise Control) and AICC (Autonomous Intelligent Cruise Control) control laws. For ramp metering, an initial evaluation has been conducted concentrating on the effect of vehicle emissions. Three components of ramp metering were evaluated independently: 1) the effect of freeway traffic smoothing, 2) ramp and surface street congestion, and 3) hard accelerations from the ramp meters.