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The following chapters deal with the chemistry, catalytic poisoning, newer catalyst technologies, and possible future solutions to increase the efficiency of creating high-value products by thermochemically converting gasified biomass (producer gas). Chapter 1 puts emphasis on multifunctional catalysts containing transition metals that are used for renewable fuel production. High-value products such as gasoline-range hydrocarbons, dimethyl ether (DME), aldehydes, isobutane, isobutene and other olefins can be produced with gasified biomass due to the gas containing syngas (H2 + CO). The chemistry and production of these chemicals is discussed in the review. Chapter 2 describes the reactor design of a bench scale system and results after using a Mo/HZSM- 5 catalyst for aromatic hydrocarbon creation. This chapter also discusses issues that came with trying to control the temperature without any reactor intercooling. Chapter 3 shows the feasibility of using a particular multifunctional catalyst with a lab scale system and also shows the importance of certain process variables including temperature, space velocity, gas ratios, and pressure. The subject of the importance of the cleanliness of the producer gas is also discussed so that maximum high-value product yield can be achieved with the greatest efficiency. Chapter 4 discusses the implementation of a bench scale and pilot scale reactor design (both with intercooling) and the results of scale-up when using the catalyst mentioned in Chapter 3. Chapter 5 involves the modelling of an industrialized system with Aspen Plus. The economics of industrial plants to produce hydrocarbons from coal or wood feedstocks at scales of 5, 50 and 5000 tons per day were modeled using CAPCOST.

Human activities and rapid global climate change are altering fire regimes with potential threat to the stability of aspen ecosystems in North America. Aspen is an early successional species that plays an important role in post-fire forest reestablishment, but chronic browsing on juvenile aspen by large ungulate herbivores after fire can be detrimental and lead to regeneration failure. Although larger and more severe fires are expected to become more prominent, whether and how this may influence aspen and ungulate communities remains unclear. The objective of this research was to examine how the relationship between aspen and ungulate communities might be influenced by variation in fire severity and size. In 2012, we examined browse patterns, growth responses and defense chemistry (phenolic glycoside and condensed tannins) concentrations of regenerating aspen that experienced variable burn severity in the 2010 Twitchell Canyon Fire, Utah, USA. We found that greater light availability in higher severity burn environments enhanced aspen tolerance and resistance against herbivory by increasing growth potential and defense chemistry concentrations of aspen. These results suggest that burn severity influences plant-herbivore interactions through bottom-up and top-down forces, and that higher fire severity increases post-disturbance vegetation recruitment potential by increasing resilience to herbivory. In 2013, we characterized aspen and ungulate patterns of 25 fires that spread across five National Forests (Uinta-Wasatch-Cache NF, Ashley NF, Fishlake NF, Dixie NF, and Manti-La Sal NF) in the state of Utah. We identified interaction effects between fire size and severity that strongly influenced aspen and ungulate densities. Fire size and severity are important ecological filters that can interact to affect forest reestablishment and community response. This information is useful in developing decision-making tools for wildfire and ungulate management that can more effectively increase the long-term resilience of forests systems.

In 2015, more than 80% of energy consumption was based on fossil resources. Growing population especially in developing countries fuel the trend in global energy consumption. This constant increase however leads to climate change caused by anthropogenic greenhouse gas (GHG) emissions. GHG, especially CO2 mitigation is one of the top priority challenges in the EU. Amongst the solutions to mitigate future emissions, carbon capture and utilization (CCU) is gaining interest. CO2 is a valuable, abundant and renewable carbon source that can be converted into fuels and chemicals. Methanol (MeOH) is one of the chemicals that can be produced from CO2. It is considered a basic compound in chemical industry as it can be utilised in a versatility of processes. These arguments make methanol and its production from CO2 a current, intriguing topic in climate change mitigation. In this master’s thesis first the applications, production, global demand and market price of methanol were investigated. In the second part of the thesis, a methanol plant producing chemical grade methanol was simulated in Aspen Plus. The studied plants have three different annual capacities: 10 kt/a, 50 kt/a and 250 kt/a. They were compared with the option of buying the CO2 or capturing it directly from flue gases through a carbon capture (CC) unit attached to the methanol plant. The kinetic model considering both CO and CO2 as sources of carbon for methanol formation was described thoroughly, and the main considerations and parameters were introduced for the simulation. The simulation successfully achieved chemical grade methanol production, with a high overall CO2 conversion rate and close to stoichiometric raw material utilization. Heat exchanger network was optimized in Aspen Energy Analyzer which achieved a total of 75% heat duty saving. The estimated levelised cost of methanol (LCOMeOH) ranges between 1130 and 630 €/t which is significantly higher than the current listed market price for fossil methanol at 419 €/t. This high LCOMeOH is mostly due to the high production cost of hydrogen, which corresponds to 72% of LCOMeOH. It was revealed that selling the oxygen by-product from water electrolysis had the most significant effect, reducing the LCOMeOH to 475 €/t. Cost of electricity also has a significant influence on the LCOMeOH, and for a 10 €/MWh change the LCOMeOH changed by 110 €/t. Finally, the estimated LCOMeOH was least sensitive for the change in cost of CO2. When comparing owning a CC plant with purchasing CO2, it was revealed that purchasing option is only beneficial for smaller plants.

Due to the remote and dispersed nature of Alberta’s oil wells, it is not economical for the energy industry to capture all of the solution gas produced and as a result, the gas is being flared and vented in significant amounts. The objective of this research is to aid in the conversion of solution gas into dimethyl ether (DME) in a remote location by designing a distillation column that purifies DME and its reaction by-products, carbon dioxide, methanol and water. In order to develop an implementable solution, the distillation equipment must fit inside of a 40-foot shipping container to be transported to remote locations. Given the size constraint of the system, process intensification is the best strategy to efficiently separate the mixture. Several process intensification distillation techniques are explored, including semicontinuous distillation, the dividing wall column (DWC) and a novel semicontinuous dividing wall column (S-DWC). The traditional semicontinuous distillation column purifies DME to fuel grade purity, however the other components are not separated to a high enough grade given the height constrain of the system. The DWC and S-DWC both purify DME to its desired purity along with producing high purity waste streams. The S-DWC purifies the reaction intermediate methanol to a grade slightly higher than the DWC and is pure enough to recycle back to the reactor. An economic comparison is made between the three systems. While the DWC is a cheaper method of producing DME, the trade-off is the purity of the methanol produced. Overall, this research shows that it is possible to purify DME and its reaction by-products in a 40-foot distillation column at a cost that is competitive with Diesel. / Thesis / Master of Applied Science (MASc)

Six forest areas destroyed by fire representing different seral stages of aspen development and conifer invasion were studied to determine successional dynamics and the related livestock and big game use. Factors measured were: (a) age, basal area, density and frequency of aspen and conifer trees; (b) density and frequency of under-story species; (c) forage production for forbs, grasses, and browse, and (d) animal-days use for deer, cattle and sheep. Aspen appeared in the community the spring following the fire and conifers appeared fifteen to twenty years later. Conifers had begun to dominate aspen on an eighty-two year old stand. The density and frequency of understory species was influenced by grazing pressure, age of the cormnunity and conifer basal area. Maximum densities were reached twenty years after the fire. Forage production was influenced by the age of the community and conifer basal area. Maximum forage production was reached on the twenty-one year old burn. Animal use was influenced by the amount of forage production, conifer basal area and competitive use by other animals.

Human activities and expansion have created novel disturbance patterns across Earth’s landscapes. Disturbance is an ecological interruption after which ecosystem recovery or transition into a new state can occur, affecting biodiversity, ecosystem functioning, and theavailability of ecosystem services. Fire and herbivory are two of the most widespread forces of disturbance which shape ecosystems globally. In temperate forest ecosystems, fire affects forest composition, which influences the diversity and resilience of ecosystems (chapters 1 and 2) and forest canopy structure, which is important to snowpack accumulation and the availability of water resources (chapters 3 and 4). In chapter one, the effects of conifer competition, which occurs under fire suppression, and ungulate herbivory on aspen regeneration and recruitmentwere examined. It was found that conifer competition, and ungulate herbivory both drastically reduced successful aspen regeneration and recruitment and had a larger effect than climatic or topographical variables. In chapter two, this understanding was used to investigate mechanicaland fire interventions by the National Forest Service in a mixed aspen conifer forest experiencing fire suppression and heavy ungulate herbivory. Untreated forests failed to recruit aspen suckers successfully due to conifer competition and ungulate browsing. Fire treatments were successful in restoring aspen habitat, but mechanical treatments failed due to heavy ungulate use, despitethe treatment eliciting high sucker densities. In chapter three, fire severity was found to have important implications for snowpack accumulation and snow-water content in alpine forests. High burn severity, which is projected to become more common under future climaticconditions, led to deeper and denser snowpack possibly buffering the effects of water loss in a warmer climate. In chapter four, the interaction between topography and vegetation in burned forest conditions was evaluated. It was found that topographical aspect likely mediates the effect of vegetation on snowpack and may have an opposite effect on snow accumulation and melt on north vs south facing aspects. A synthesis of studies from different regions further supports the idea that this relationship between fire and snow is heavily dependent on latitude, elevation, and slope angle. Together, these findings demonstrate that the resilience and persistence of aspenforest ecosystems in changing disturbance regimes depend on complex interactions among disturbance type, disturbance severity, landscape position, and hydrology. These interactions should be integrated into management strategies to protect ecosystems and ensure ecosystemservices for growing human populations in the western United States.

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Yes / Process simulation of a single-step synthesis of DME based on CO2-enhanced gasification of rice straw was conducted using Aspen PlusTM. The process consists of gasification unit, heat recovery unit, gas purification unit, single-step DME synthesis, and DME separation unit. In the simulation, highly pure DME was produced by the control of CO2 concentration in syngas to a very low level prior to synthesis. A gasification system efficiency of 36.7% and CO2 emission of 1.31 kg/kg of DME were achieved. Bio-DME production based on CO2-enhanced gasification of biomass was found to be more cost-effective as it required 19.6% less biomass than that of DME production based on conventional biomass gasification. The performance and environmental benefits of the proposed process could be further improved by the utilization of unreacted gases and the handling of CO2 generated via incorporating poly-generation concept or carbon storage, which could also potentially improve process economics. / Ningbo Bureau of Science and Technology; Innovation Team Scheme; Major R&D Programme; Provincial Innovation Team on the Commercialisation of SOx and NOx Removal Technologies; University of Nottingham Ningbo China

Yes / The biomass gasification process is widely accepted as a popular technology to produce fuel for the application in gas turbines and Organic Rankine Cycle (ORC). Chemical reactions of this process can be separated into three reaction zones: pyrolysis, combustion, and reduction. In this study, sensitivity analysis with respect to three input parameters (gasification temperature, equivalence ratio, and steam-to-biomass ratio) has been carried out to achieve energy self-sufficient conditions in a steam gasification process under the criteria that the carbon conversion efficiency must be more than 70%, and carbon dioxide gas is lower than 20%. Simulation models of the steam gasification process have been carried out by ASPEN Plus and validated with both experimental data and simulation results from Nikoo & Mahinpey (2008). Gasification temperature of 911 °C, equivalence ratio of 0.18, and a steam-to-biomass ratio of 1.78, are considered as an optimal operation point to achieve energy self-sufficient condition. This operating point gives the maximum of carbon conversion efficiency at 91.03%, and carbon dioxide gas at 15.18 volumetric percentages. In this study, life cycle assessment (LCA) is included to compare the environmental performance of conventional and energy self-sufficient gasification for steam biomass gasification. / Financing of this research was supported by the Thailand Research Fund (TRF) under Grant Number PHD57I0054 and the Institutional Research Grant by the Thailand Research Fund (TRF) under Grant Number IRG 5780014 and Chulalongkorn University, Contact No. RES_57_411_21_076.