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The dissertation begins with the explanation of the framework of the dissertation, discusses the background of the study, the motivation and value of the study. The problem statement and study objectives are defined as well as the research methodology. In line with the objectives of the study, various capital structure theories are examined the importance of the weighted average cost of capital is analyzed and the specific components that make up the weighted average cost of capital namely, the cost of equity and cost of debt are explored. Further more the signaling and agency costs theories are also extensively discussed and many other concepts and theories of significance to capital structure management. The corporate profile of Aspen Pharmacare is discussed as well as the industry within which the company operates, the strategic alliances and agreements entered into, in line with the company's growth strategy. The company's financial statements are analysed so as to compute the gearing level. The dissertation concludes by saying that the gearing ratio needs to be looked at in comparison to the company peers in the industry, so as to best establish the norm of the industry, and that, it is only then that a conclusive statement can be made as to whether the company gearing strategy is appropriate or not. / Thesis (MBA)-University of Natal, 2003.

The global fossil reserves are dwindling and there is need to find alternative sources of energy. With global warming in mind, some of the most commonly considered suitable alternatives include solar, wind, nuclear, geothermal and hydro energy. A common challenge with use of most alternative energy sources is ensuring continuity of supply, which necessitates the use of energy storage. Hydrogen has properties that make it attractive as an energy carrier. To efficiently store energy from alternative sources in hydrogen, several methods of hydrogen production are under study. Several literature sources show thermochemical cycles as having high potential but requiring further development. Using literature sources, an initial screening of thermochemical cycles was done to select a candidate thermochemical cycle. The copper–chlorine thermochemical cycle was selected due to its relatively low peak operating temperature, which makes it flexible enough to be connected to different energy sources. Once the copper–chlorine cycle was identified, the three main copper–chlorine cycles were simulated in Aspen Plus to examine which is the best configuration. Using experimental data from literature and calculating optimal conditions, flowsheets were developed and simulated in Aspen Plus. The simulation results were then used to determine the configuration with the most favourable energy requirements, cycle efficiency, capital requirements and product cost. Simulation results show that the overall energy requirements increase as the number of steps decrease from five–steps to three–steps. Efficiencies calculated from simulation results show that the four and five–step cycles perform closely with 39% and 42%, respectively. The three–step cycle has a much lower efficiency, even though the theoretical calculations imply that the efficiency should also be close to that of the four and five–step cycles. The five–step reaction cycle has the highest capital requirements at US$370 million due to more equipment and the three–step cycle has the lowest requirement at US$ 275 million. Payback analysis and net present value analysis indicate that the hydrogen costs are highest for the three–step cycle at between US$3.53 per kg for a 5–10yr payback analysis and the five–step cycle US$2.98 per kg for the same payback period. / Thesis (M.Ing. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2012.

The global fossil reserves are dwindling and there is need to find alternative sources of energy. With global warming in mind, some of the most commonly considered suitable alternatives include solar, wind, nuclear, geothermal and hydro energy. A common challenge with use of most alternative energy sources is ensuring continuity of supply, which necessitates the use of energy storage. Hydrogen has properties that make it attractive as an energy carrier. To efficiently store energy from alternative sources in hydrogen, several methods of hydrogen production are under study. Several literature sources show thermochemical cycles as having high potential but requiring further development. Using literature sources, an initial screening of thermochemical cycles was done to select a candidate thermochemical cycle. The copper–chlorine thermochemical cycle was selected due to its relatively low peak operating temperature, which makes it flexible enough to be connected to different energy sources. Once the copper–chlorine cycle was identified, the three main copper–chlorine cycles were simulated in Aspen Plus to examine which is the best configuration. Using experimental data from literature and calculating optimal conditions, flowsheets were developed and simulated in Aspen Plus. The simulation results were then used to determine the configuration with the most favourable energy requirements, cycle efficiency, capital requirements and product cost. Simulation results show that the overall energy requirements increase as the number of steps decrease from five–steps to three–steps. Efficiencies calculated from simulation results show that the four and five–step cycles perform closely with 39% and 42%, respectively. The three–step cycle has a much lower efficiency, even though the theoretical calculations imply that the efficiency should also be close to that of the four and five–step cycles. The five–step reaction cycle has the highest capital requirements at US$370 million due to more equipment and the three–step cycle has the lowest requirement at US$ 275 million. Payback analysis and net present value analysis indicate that the hydrogen costs are highest for the three–step cycle at between US$3.53 per kg for a 5–10yr payback analysis and the five–step cycle US$2.98 per kg for the same payback period. / Thesis (M.Ing. (Chemical Engineering))--North-West University, Potchefstroom Campus, 2012.

The modern concept of “biorefinery” is dominantly based on chemical pulp mills to create more value than cellulose pulp fibres, and energy from the dissolved lignins and hemicelluloses. This concept is characterized by the conversion of biomass into various bio-based products. It includes thermochemical processes such as gasification and fast pyrolysis. In thermo-mechanical pulp (TMP) mills, the feedstock available to the gasification-based biorefinery is significant, including logging residues, bark, fibre material rejects, bio-sludges and other available fuels such as peat, recycled wood and paper products. On the other hand, mechanical pulping processes consume a great amount of electricity, which may account for up to 40% of the total pulp production cost. The huge amount of purchased electricity can be compensated for by self-production of electricity from gasification, or the involved cost can be compensated for by extra revenue from bio-transport fuel production. This work is to study co-production of bio-automotive fuels, bio-power, and steam via gasification of the waste biomass streams in the context of the mechanical pulp industry. Ethanol and substitute natural gas (SNG) are chosen to be the bio-transport fuels in the study. The production processes of biomass-to-ethanol, SNG, together with heat and power, are simulated with Aspen Plus. Based on the model, the techno-economic analysis is made to evaluate the profitability of bio-transport fuel production when the process is integrated into a TMP mill.The mathematical modelling starts from biomass gasification. Dual fluidized bed gasifier (DFBG) is chosen for syngas production. From the model, the yield and composition of the syngas and the contents of tar and char can be calculated. The model has been evaluated against the experimental results measured on a 150 KWth Mid Sweden University (MIUN) DFBG. As a reasonable result, the tar content in the syngas decreases with the gasification temperature and the steam to biomass (S/B) ratio. The biomass moisture content is a key parameter for a DFBG to be operated and maintained at a high gasification temperature. The model suggests that it is difficult to keep the gasification temperature above 850 ℃ when the biomass moisture content is higher than 15.0 wt.%. Thus, a certain amount of biomass or product gas needs to be added in the combustor to provide sufficient heat for biomass devolatilization and steam reforming.For ethanol production, a stand-alone thermo-chemical process is designed and simulated. The techno-economic assessment is made in terms of ethanol yield, synthesis selectivity, carbon and CO conversion efficiencies, and ethanol production cost. The calculated results show that major contributions to the production cost are from biomass feedstock and syngas cleaning. A biomass-to-ethanol plant should be built over 200 MW.In TMP mills, wood and biomass residues are commonly utilized for electricity and steam production through an associated CHP plant. This CHP plant is here designed to be replaced by a biomass-integrated gasification combined cycle (BIGCC) plant or a biomass-to-SNG (BtSNG) plant including an associated heat & power centre. Implementing BIGCC/BtSNG in a mechanical pulp production line might improve the profitability of a TMP mill and also help to commercialize the BIGCC/BtSNG technologies by taking into account of some key issues such as, biomass availability, heat utilization etc.. In this work, the mathematical models of TMP+BIGCC and TMP+BtSNG are respectively built up to study three cases: 1) scaling of the TMP+BtSNG mill (or adding more forest biomass logging residues in the gasifier for TMP+BIGCC); 2) adding the reject fibres in the gasifier; 3) decreasing the TMP SEC by up to 50%.The profitability from the TMP+BtSNG mill is analyzed in comparison with the TMP+BIGCC mill. As a major conclusion, the scale of the TMP+BIGCC/BtSNG mill, the prices of electricity and SNG are three strong factors for the implementation of BIGCC/BtSNG in a TMP mill. A BtSNG plant associated to a TMP mill should be built in a scale above 100 MW in biomass thermal input. Comparing to the case of TMP+BIGCC, the NR and IRR of TMP+BtSNG are much lower. Political instruments to support commercialization of bio-transport fuel are necessary. / Gasification-based Biorefinery for Mechanical Pulp Mills

The impacts of aspen clear-cutting on upland groundwater recharge are presented based on two years (2007-2008) of the five year (2005-2009) HEAD2 NSERC-CRD paired-catchment experiment. Research was conducted at the Utikuma Region Study Area (URSA), 370 km north of Edmonton, Alberta, Canada, in the Boreal Plain ecozone. Results show greater soil water content in the root zone and potential for recharge into the deeper unsaturated zone during the first year of regeneration. Sites with shallow water table levels (<600 cm) increased more than sites under uncut conditions. Sites with deeper water table levels (>600 cm) responded minimally, if at all, to spring-melt and summer storms suggesting that water exchanges with the atmosphere occurred to and from the unsaturated zone only during the first-year regeneration. Upland groundwater gradients to adjacent pond-peatland complexes persisted at least ten times longer under clear-cut than under uncut conditions. Water table trends recovered to uncut conditions by the second year of regeneration. / Ecology

Thesis (Ph. D.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 85-94). Also available on the World Wide Web.

Submitted by Isaac Francisco de Souza Dias (isaac.souzadias@ufpe.br) on 2015-05-18T18:24:59Z No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) TESE - Thibério - Parte escrita - 81 - FINAL.pdf: 8671428 bytes, checksum: 626d3d6a70a811bf559ef1ba89a7d967 (MD5) / Made available in DSpace on 2015-05-18T18:24:59Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) TESE - Thibério - Parte escrita - 81 - FINAL.pdf: 8671428 bytes, checksum: 626d3d6a70a811bf559ef1ba89a7d967 (MD5) Previous issue date: 2015-04-04 / CAPES / Nos últimos anos o biodiesel se tornou uma alternativa para a demanda crescente de combustível no país e no mundo. O próximo passo é conseguir produzir um biodiesel economicamente competitivo com o diesel fóssil em um processo a nível industrial. Uma tecnologia que vem ganhando espaço ultimamente é a destilação reativa. O objetivo deste trabalho foi estudar do ponto de vista computacional e experimental a produção de biodiesel por destilação reativa. Para isso, foi construída uma coluna piloto com 1,5 m de altura em vidro, dotada de toda parte de controle automático para a aquisição de dados. Foi utilizado o Aspen Plus® para realizar as simulações com base nos resultados obtidos experimentalmente. Também foi realizado neste trabalho uma modelagem cinética da transesterificação do óleo de algodão em rota etílica a fim de se obter parâmetros da reação para serem inseridos no simulador. Em seguida, foi comparada a viabilidade da rota etílica com a metílica via simulação e sugerido um processo de extração com o próprio glicerol. Os resultados mostraram que a destilação reativa apresenta melhor desempenho quando comparado a outros processos como por exemplo reatores PFR também estudados neste trabalho. Por fim, foi sugerido um projeto de uma coluna de destilação reativa, extrativa e absortiva para a produção de biodiesel.