Liquid Phase Conversion of Biomass to Renewable Fuels and Chemicals

Renewable energy, currently occupying an appreciable portion of global energy, plays a major role in reducing greenhouse gas emissions. Biomass resources, which are superior to other renewables in terms of flexible transportation and storage, are widely available. Renewable liquid fuels production is the central theme of biomass conversion due to the significant market demand in the transportation sector. Coproduction of high value-added chemicals in an integrated biorefinery is also important from an economic perspective. However, there are still significant challenges for developing efficient biomass conversion technologies that would produce cost-competitive fuels and chemicals. Conventional thermochemical processes including pyrolysis or gasification have been extensively studied but still suffer from various drawbacks such as energy-intensive, low carbon efficiency, and so on. In contrast, liquid-phase processes have not been explored as thoroughly but have the potential to achieve high efficiencies.In this dissertation, four different liquid-phase catalytic processes are investigated for the conversion of a variety of biomass feedstocks: First, carbohydrates were converted to lactic acid over a perovskite LaCoOx catalyst with the redox properties in hydrothermal media. Second, dairy manure was fractionated and transformed to ethyl lactate, aromatic esters, and ethyl fatty acid esters, etc. in supercritical ethanol with the Zr-SBA-15 Lewis acid catalyst. Third, the aqueous-phase hydrodeoxygenation of Grindelia biocrude was carried out on the bifunctional heterogeneous palladium on tungstated zirconia catalyst. Lastly, the novel biphasic tandem catalytic process (BiTCP) was used to convert mono- and diterpenoids to cycloalkanes, which are high-density jet fuel components, with the homogeneous trifluoroacetic acid and the hydrophobic carbon-supported palladium catalysts in aqueous and cyclohexane solutions, respectively. This novel process was able to convert fatty acids and triglycerides to renewable diesel efficiently. Remarkably high carbon efficiencies were obtained in the conversion of terpenoids and lipids to paraffinic hydrocarbons. For each liquid-phase catalytic process, the reaction mechanism was investigated to gain a fundamental understanding of the effects of catalyst properties and process conditions on the conversion of the different types of biomass feedstock. The recommendations for future research are included at the end of the dissertation

Tourism: an alternative to development?: reconsidering farming, tourism and conservation incentives in Northwest Yunnan mountainous communities

In the last decade, tourism has developed rapidly in the mountainous areas of northwest Yunnan. This growth has led to substantial economic and social changes, with resulting environmental consequences. This article uses a case study to illustrate how local farmers involved in tourism changed their agricultural practices as a result of the transformations that took place in the area. The aim was to examine tourism's expected benefits of poverty alleviation and conservation incentives. Tourism investments were found to have been adopted only by households with available cash and labor, whereas they remained inaccessible for the poor, small landowners who most needed a new source of income and used their land more exhaustively. Relatively rich, large landowners did not take the opportunity to reduce their agricultural activities. Instead, they used supplementary incomes earned from tourism to hire external labor to cultivate their land more intensely. Tourism development failed to generate real incentives for mountain farmers to adopt more conservation measures and prevent soil erosion and nonpoint source agricultural water pollution, which currently constitute serious environmental problems for mountain environments in Yunnan. This article presents recommendations based on the conclusions of the study

Modelling and region stability analysis of wind turbines with battery energy storage system based on switched system with multi-equilibriums

This paper deals with the modelling and control for wind turbine combined with a battery energy storage system (WT/BESS). A proportional-integral (PI) controller of pitch angle is applied to adjust the output power of WT, and a method for battery scheduling is presented for maintaining the state of charging (SOC) of BESS. When the battery level is below the lower limit, we increase the expected output power of wind turbine through raising the operation point to charge the battery. Considering the effect of charging/discharging, a switched linear system model with two equilibriums is presented firstly for such WT/BESS system. The region stability is analyzed and an approach for estimating the corresponding stable region is also given. The effectiveness of the proposed results is demonstrated by a numerical example

A GIS approach towards estimating tourist's off-road use in a mountainous protected area of Northwest Yunnan, China

To address the environmental impacts of tourism in protected areas, park managers need to understand the spatial distribution of tourist use. Standard monitoring measures (tourist surveys and counting and tracking techniques) are not sufficient to accomplish this task, in particular for off-road travel. This article predicts tourists' spatial use patterns through an alternative approach: park accessibility measurement. Naismith's rule and geographical information system's anisotropic cost analysis are integrated into the modeling process, which results in a more realistic measure of off-road accessibility than that provided by other measures. The method is applied to a mountainous United Nations Educational, Scientific and Cultural Organization (UNESCO) World Heritage Site in northwest Yunnan Province, China, where there is increasing concern about potential impacts of unregulated tourist use. Based on the assumption that accessibility tends to attract more tourists, a spatial pattern of predicted off-road use by tourists is derived. This pattern provides information that can help park managers develop strategies that are effective for both tourism management and species conservation