Dissertations / Theses on the topic 'Economic aspects of Biomass gasification'

L’épuisement des ressources fossiles et la nécessité de réduire les émissions de gaz à effet de serre incitent à rechercher de nouvelles sources d’énergie à la fois renouvelables et moins polluantes. La biomasse, par son abondance, apparaît comme une filière intéressante de remplacement des énergies fossiles et notamment du pétrole. L’objectif de ce travail est d’effectuer une analyse 4E (Energétique, Exergétique, Environnementale et Economique) d’un système de production de l’électricité via la gazéification des déchets de palmiers. Ces derniers constituent l’une des richesses végétales les plus abondantes en Tunisie et qui de nos jours, restent très peu exploitées. Un gazéifieur à lit fixe couplé à un moteur à combustion interne est considéré pour produire 330kW d’électricité. Le rendement de gazéification « Cold Gaz Efficiency » du procédé est de 58,58%. Les résultats montrent que les rendements énergétique et exergétique du système étudié sont de 22,6% et 19,22%, respectivement. Les performances environnementales du système sont évaluées à l’aide d’une Analyse de Cycle de Vie (ACV). L’évaluation économique est réalisée dans le but d’évaluer le coût de production de l’électricité par l’installation de gazéification. Les résultats donnent un coût de 3,88ct€ pour 1kWh
The fossil fuels depletion and the need to reduce greenhouse gas emissions encourage the search for new energy sources that are renewable and less polluting. Thanks to its abundance, biomass appears as an interesting sector of replacement of fossil fuels. The objective of this work is to perform a 4E analysis (Energy, Exergy, Environmental and Economic) of an electricity production system via the gasification of palm waste. Palm watse constitutes one of the most abundant vegetable wealth in Tunisia and which today, remain very little exploited. A fixed bed gasifier coupled to an internal combustion engine is considered to produce330 kW of electricity. The Cold Gas Efficiency of the process is 58.58%. The results show that the energy and exergy yields of the system are 22.6% and 19.22%, respectively. The environmental performance of the system is evaluated using a Life Cycle Assessment (LCA). The economic evaluation is carried out in order to evaluate the cost of electricity production by the gasification plant. The results give a cost of 3.88 ct€ for 1kWh

Fossil fuels continue to deplete with use as they are irreplaceable. In addition, the environmental impact with the continuous use of these conventional fuels has generated global concern due to the production of harmful emission gases. An alternative source of energy has become inevitable. Technological advancements in the area of biomass use for both aviation and power generation are at different levels of development. There is however the need for an integrated approach to assess gas turbine engine behaviour in terms of performance, emission and economics when they are running on biofuels. The current research work is concerned with finding alternative fuel resources for use on stationary gas turbine engines for power generation with the necessary identification of suitable biofuels using a multidisciplinary approach. A techno-economic, environmental and risk assessment (TERA) model comprising the performance, emissions, economics and risk modules has been developed. There had been several simulations of two gas turbine engines (GTEs) to ascertain the effects of both ambient and operating conditions and the effect of fuel types on the engines. These simulations were done with the use of an in-house code-the Turbomatch and a code developed for the steam cycle which is employed for the combined cycle simulation. Cont/d.

In such territories where food production is mostly scattered in several small / medium size or even domestic farms, a lot of heterogeneous residues are produced yearly, since farmers usually carry out different activities in their properties. The amount and composition of farm residues, therefore, widely change during year, according to the single production process periodically achieved. Coupling high efficiency micro-cogeneration energy units with easy handling biomass conversion equipments, suitable to treat different materials, would provide many important advantages to the farmers and to the community as well, so that the increase in feedstock flexibility of gasification units is nowadays seen as a further paramount step towards their wide spreading in rural areas and as a real necessity for their utilization at small scale. Two main research topics were thought to be of main concern at this purpose, and they were therefore discussed in this work: the investigation of fuels properties impact on gasification process development and the technical feasibility of small scale gasification units integration with cogeneration systems. According to these two main aspects, the present work was thus divided in two main parts. The first one is focused on the biomass gasification process, that was investigated in its theoretical aspects and then analytically modelled in order to simulate thermo-chemical conversion of different biomass fuels, such as wood (park waste wood and softwood), wheat straw, sewage sludge and refuse derived fuels. The main idea is to correlate the results of reactor design procedures with the physical properties of biomasses and the corresponding working conditions of gasifiers (temperature profile, above all), in order to point out the main differences which prevent the use of the same conversion unit for different materials. At this scope, a gasification kinetic free model was initially developed in Excel sheets, considering different values of air to biomass ratio and the downdraft gasification technology as particular examined application. The differences in syngas production and working conditions (process temperatures, above all) among the considered fuels were tried to be connected to some biomass properties, such elementary composition, ash and water contents. The novelty of this analytical approach was the use of kinetic constants ratio in order to determine oxygen distribution among the different oxidation reactions (regarding volatile matter only) while equilibrium of water gas shift reaction was considered in gasification zone, by which the energy and mass balances involved in the process algorithm were linked together, as well. Moreover, the main advantage of this analytical tool is the easiness by which the input data corresponding to the particular biomass materials can be inserted into the model, so that a rapid evaluation on their own thermo-chemical conversion properties is possible to be obtained, mainly based on their chemical composition A good conformity of the model results with the other literature and experimental data was detected for almost all the considered materials (except for refuse derived fuels, because of their unfitting chemical composition with the model assumptions). Successively, a dimensioning procedure for open core downdraft gasifiers was set up, by the analysis on the fundamental thermo-physical and thermo-chemical mechanisms which are supposed to regulate the main solid conversion steps involved in the gasification process. Gasification units were schematically subdivided in four reaction zones, respectively corresponding to biomass heating, solids drying, pyrolysis and char gasification processes, and the time required for the full development of each of these steps was correlated to the kinetics rates (for pyrolysis and char gasification processes only) and to the heat and mass transfer phenomena from gas to solid phase. On the basis of this analysis and according to the kinetic free model results and biomass physical properties (particles size, above all) it was achieved that for all the considered materials char gasification step is kinetically limited and therefore temperature is the main working parameter controlling this step. Solids drying is mainly regulated by heat transfer from bulk gas to the inner layers of particles and the corresponding time especially depends on particle size. Biomass heating is almost totally achieved by the radiative heat transfer from the hot walls of reactor to the bed of material. For pyrolysis, instead, working temperature, particles size and the same nature of biomass (through its own pyrolysis heat) have all comparable weights on the process development, so that the corresponding time can be differently depending on one of these factors according to the particular fuel is gasified and the particular conditions are established inside the gasifier. The same analysis also led to the estimation of reaction zone volumes for each biomass fuel, so as a comparison among the dimensions of the differently fed gasification units was finally accomplished. Each biomass material showed a different volumes distribution, so that any dimensioned gasification unit does not seem to be suitable for more than one biomass species. Nevertheless, since reactors diameters were found out quite similar for all the examined materials, it could be envisaged to design a single units for all of them by adopting the largest diameter and by combining together the maximum heights of each reaction zone, as they were calculated for the different biomasses. A total height of gasifier as around 2400mm would be obtained in this case. Besides, by arranging air injecting nozzles at different levels along the reactor, gasification zone could be properly set up according to the particular material is in turn gasified. Finally, since gasification and pyrolysis times were found to considerably change according to even short temperature variations, it could be also envisaged to regulate air feeding rate for each gasified material (which process temperatures depend on), so as the available reactor volumes would be suitable for the complete development of solid conversion in each case, without even changing fluid dynamics behaviour of the unit as well as air/biomass ratio in noticeable measure. The second part of this work dealt with the gas cleaning systems to be adopted downstream the gasifiers in order to run high efficiency CHP units (i.e. internal engines and micro-turbines). Especially in the case multi–fuel gasifiers are assumed to be used, weightier gas cleaning lines need to be envisaged in order to reach the standard gas quality degree required to fuel cogeneration units. Indeed, as the more heterogeneous feed to the gasification unit, several contaminant species can simultaneously be present in the exit gas stream and, as a consequence, suitable gas cleaning systems have to be designed. In this work, an overall study on gas cleaning lines assessment is carried out. Differently from the other research efforts carried out in the same field, the main scope is to define general arrangements for gas cleaning lines suitable to remove several contaminants from the gas stream, independently on the feedstock material and the energy plant size The gas contaminant species taken into account in this analysis were: particulate, tars, sulphur (in H2S form), alkali metals, nitrogen (in NH3 form) and acid gases (in HCl form). For each of these species, alternative cleaning devices were designed according to three different plant sizes, respectively corresponding with 8Nm3/h, 125Nm3/h and 350Nm3/h gas flows. Their performances were examined on the basis of their optimal working conditions (efficiency, temperature and pressure drops, above all) and their own consumption of energy and materials. Successively, the designed units were combined together in different overall gas cleaning line arrangements, paths, by following some technical constraints which were mainly determined from the same performance analysis on the cleaning units and from the presumable synergic effects by contaminants on the right working of some of them (filters clogging, catalysts deactivation, etc.). One of the main issues to be stated in paths design accomplishment was the tars removal from the gas stream, preventing filters plugging and/or line pipes clogging At this scope, a catalytic tars cracking unit was envisaged as the only solution to be adopted, and, therefore, a catalytic material which is able to work at relatively low temperatures was chosen. Nevertheless, a rapid drop in tars cracking efficiency was also estimated for this same material, so that an high frequency of catalysts regeneration and a consequent relevant air consumption for this operation were calculated in all of the cases. Other difficulties had to be overcome in the abatement of alkali metals, which condense at temperatures lower than tars, but they also need to be removed in the first sections of gas cleaning line in order to avoid corrosion of materials. In this case a dry scrubber technology was envisaged, by using the same fine particles filter units and by choosing for them corrosion resistant materials, like ceramic ones. Besides these two solutions which seem to be unavoidable in gas cleaning line design, high temperature gas cleaning lines were not possible to be achieved for the two larger plant sizes, as well. Indeed, as the use of temperature control devices was precluded in the adopted design procedure, ammonia partial oxidation units (as the only considered methods for the abatement of ammonia at high temperature) were not suitable for the large scale units, because of the high increase of reactors temperature by the exothermic reactions involved in the process. In spite of these limitations, yet, overall arrangements for each considered plant size were finally designed, so that the possibility to clean the gas up to the required standard degree was technically demonstrated, even in the case several contaminants are simultaneously present in the gas stream. Moreover, all the possible paths defined for the different plant sizes were compared each others on the basis of some defined operational parameters, among which total pressure drops, total energy losses, number of units and secondary materials consumption. On the basis of this analysis, dry gas cleaning methods proved preferable to the ones including water scrubber technology in al of the cases, especially because of the high water consumption provided by water scrubber units in ammonia adsorption process. This result is yet connected to the possibility to use activated carbon units for ammonia removal and Nahcolite adsorber for chloride acid. The very high efficiency of this latter material is also remarkable. Finally, as an estimation of the overall energy loss pertaining the gas cleaning process, the total enthalpy losses estimated for the three plant sizes were compared with the respective gas streams energy contents, these latter obtained on the basis of low heating value of gas only. This overall study on gas cleaning systems is thus proposed as an analytical tool by which different gas cleaning line configurations can be evaluated, according to the particular practical application they are adopted for and the size of cogeneration unit they are connected to.

Pressurised entrained-flow gasification (PEFG) of woody biomass has the potential to produce high purity syngas for the production of vital chemicals, e.g., biofuels. However, ash-related issues such as reactor blockages and refractory corrosion need to be addressed before this potential can be realised from a technical perspective. These undesirable consequences can be brought about by slag formation involving inorganic ash-forming elements and the chemical transformations that they undergo during fuel conversion. The objective of this study was to elucidate the ash transformations of the major ash-forming elements and the slag formation process. A pilot-scale PEFG reactor was used as the basis of the study, gasifying different woody biomass-based fuels including wood, bark, and a bark/peat mixture. Different ash fractions were collected and chemically analysed. Reactor slags had elemental distributions differing from that of the fuel ash, indicating the occurrence of fractionation of ash material during fuel conversion. Fly ash particles from a bark campaign were also heterogeneous with particles exhibiting differing compositions and physical properties; e.g., molten and crystalline formations. Si was consistently enriched in the reactor slags compared to other major ash-forming elements, while analyses of other ash fractions indicated that K was likely volatilised to a significant extent. In terms of slag behaviour, near-wall temperatures of approximately 1050-1200 °C inside the reactor were insufficient to form flowing ash slag for continuous extraction of ash material during firing the woody biomass fuels alone. However, fuel blending of a bark fuel with a silica-rich peat changed the chemical composition of the reactor slags and bulk slag flow behaviour was evident. Thermochemical equilibrium calculations supported the importance of Si in melt formation and in lowering solidus and liquidus temperatures of Ca-rich slag compositions that are typical from clean wood and bark. Viscosity estimations also showed the impact that solids have upon slag flow behaviour and corresponded qualitatively to the experimental observations. Corrosion of reactor refractory was observed. The mullite-based refractory of the reactor formed a slag with the fuel ash slag, which caused the former to flux away. Reactor blockages were also resultant because of the high viscosity of this slag near the outlet.  A preliminary study into the corrosion of different refractories was also carried out, based on firing a bark/peat mixture.  Alumina-rich refractories consisting of corundum, hibonite, mullite, and andalusite tended to form anorthite and exhibited varying degrees of degradation. Infiltration of slag was evident for all the samples and was a severe mode of degradation for some refractories. For fused-cast periclase and spinel-based refractories, slag infiltration was limited to voids and no extensive signs of refractory dissolution were found. This is also supported by a thermochemical equilibrium calculations mimicking slag infiltration that incorporated viscosity estimations. The findings from this thesis contribute towards the development of woody biomass PEFG by highlighting issues concerning ash fractionation, slag behaviours and ash\slash refractory interaction that should be investigated further.

Biomass is an attractive renewable energy resource for electricity generation, which has the potential to protect air quality, reduce dependence on fossil fuel, and improve forest health. Biomass gasification is a technology that transfers solid or liquid biomass into gaseous energy carrier (syngas) to increase the efficiency of electricity generation. The objective of this thesis is to supply a detailed feasibility study and provide a state-of-the-art economical pathway on biomass gasification application. The work of this dissertation can be separated into two parts: commercial-scale biomass integrated gasification combined cycle (BIGCC) power plants comparison and other biomass gasification system design. The first part compares eight BIGCC systems with three groups of technology variations of gasification agent, syngas combustion method, and CO2 capture and storage. By comparing on performance, economic, and environmental indicators of these systems, it is found that BIGCC systems have higher exergy efficiency and lower emissions than biomass combustion electricity production system and electricity grid. However, its levelized cost of electricity is around 27% higher than the average electricity market price. To reduce the BIGCC system’s cost, in the second part of this thesis, the potential for waste material gasification has been discussed. This part discussed the tire gasification and the gasification technology application for avian influenza poultry management. Results showed that tire gasification has a lower cost than natural gas which has the potential to reduce the BIGCC system’s cost. Moreover, gasification is an effective and economical available approach for avian influenza poultry management.

This thesis is relying on modeling of MIEC membranes inside a gasifier and it seeks to find an appropriate configuration to use in gasification setup for pure oxygen production and use it inside the gasifier in a gasification process. Application of pure oxygen instead of air can play a key role in gasification processes. Since conventional methods for separation of oxygen such as cryogenic distillation are energy intensive and some of them cannot provide full purity for oxygen, an alternative method can be a good option. This substitute method which is the focus of this study, can be achieved by using specific ceramic membranes directly inside the gasifier. Although some effort have been spent on these membranes, there is still a lack of study on direct integration inside gasifier using this technology. In the present work, a modeling study of these membranes has been carried out using Engineering Equation Solver (EES). EES is a commercial software package used for solution of systems of simultaneous non-linear equations. The gasifier model was previously prepared and was studied to simulate the behavior of a downdraft gasifier. During the simulation some hypothesizes are assumed to make the available flux, model for the chosen membrane, keep working. Besides, an alternative membrane is assumed to have more precise results. Then all the suggested configurations were studied based on energy consumption and economic aspects. The economic studies was focused on the alternative which had lower flux. So, the area of the membrane required is more. Finally, the results where compared with a similar cryogenic distillation plant used to produce pure oxygen.

The Biomass Integrated Gasification Application Systems (BIGAS) consortium is a research group whose focus is on developing modern biomass gasification technology for New Zealand's wood industry. This thesis is undertaken under objective four of the BIGAS consortium, whose goal is to develop modelling tools for aiding in the design of pilot-scale gasification plant and for assessing the economic feasibility of gasification energy plant. This thesis presents a chemical equilibrium-based gasification model and an economic feasibility assessment of gasification energy plant. Chemical equilibrium is proven to accurately predict product gas composition for large scale, greater than one megawatt thermal, updraft gasification. However, chemical equilibrium does not perform as well for small scale, 100 to 150 kilowatt thermal, Fast Internally Circulating Fluidised Bed (FICFB) gasification. Chemical equilibrium provides a number of insights on how altering gasification parameters will affect the composition of the product gas and will provide a useful tool in the design of pilot-scale plant. The economic model gives a basis for judging the optimal process and the overall appeal of integrating biomass gasification-based heat and power plants into New Zealand's MDF industry. The model is what Gerrard (2000) defines as a 'study estimate' model which has a probable range of accuracy of ±20% to ±30%. The modelling results show that gasification-gas engine plants are economically appealing when sized to meet the internal electricity demands of an MDF plant. However, biomass gasification combined cycle plants (BIGCC) and gasificationgas turbine plants are proven to be uneconomic in the New Zealand context.

Thesis (M. S.)--Chemical Engineering, Georgia Institute of Technology, 2009.
Committee Chair: Realff, Matthew; Committee Member: DeMartini, Nikolai; Committee Member: Muzzy, John; Committee Member: Sievers, Carsten.

Gasification of biomass for electricity power generation has been a proven technology in a number of countries in the world. MSW consists of biomass, glass, plastics, metallic scrap and street debris. Biomass constitutes the highest proportion of MSW and being an energy resource, implies that it can contribute tremendously to the energy needs of any country since every country is endowed with this resource which is generated in enormous tonnes per day. The challenge would then be the choice of the technology to harness this abundant energy resource subject to financial and environmental constraints.    In Uganda, MSW gasification for power generation has never been implemented in spite of the 500-600 tonnes of MSW collected per day, the biomass component of the MSW comprising 88%. MSW is instead collected in skips, transported by trucks to a landfill were it is deposited and left to decompose releasing methane (CH4) and carbon dioxide (CO2) gases which are highly potent greenhouse gases. In this regard, the many tonnes per day of MSW collected in Kampala city (area of the study) portray significant potential of generating producer gas using the technology of gasification to run engines for power generation and this study evaluated possible gasifier-engine system applications for power generation. Experiments were carried out  at the Faculty of Technology, Makerere University to determine biomass characteristics (e.g. moisture content, ash content) and gasification parameters(e.g. lower heating value)  of MSW required for gasifier-engine applications. After establishing the lower heating value of the producer gas from MSW, a theoretical design of a gasifier-engine system was investigated for possible applications with the biomass component of MSW and an economic analysis was done to assess the feasibility of the project.

In recent years, proponents of 'green and clean fuel' have argued that the costs of overreliance on fossil fuels could be reduced through transition to biofuels such as bio-ethanol. Global biofuel discourses suggest that any transition to biofuel invariably results in significant benefits, including energy independence, job creation, development of agro-industrial centres at local level and high revenue generations for the state with minimum negative impacts on the environment. With many risks and costs associated with traditional 'dirty' fuels, it is likely that many countries, particularly African countries, will move towards the 'green and clean fuel' alternative. However, until recently research has arguably paid limited attention to the local livelihood impacts related to land acquisition for biofuel development or the policy frameworks required to maximise biofuel benefits. With regards to biofuel benefits, some recent studies suggest that the much bandied potential for greater tax revenue, lowered fuel costs and wealth distribution from biofuel production have all been perverted with relatively little payoff in wage labour opportunities in return (e.g. Richardson, 2010; Wilkinson and Herrera, 2010). Based on work done in Chisumbanje communal lands of Zimbabwe (Thondhlana, 2015), this policy brief highlights the local livelihood impacts of biofuel development and discusses policy implications of the findings. By highlighting the justifications of biofuel development at any cost by the state, the study sheds some light on the conflicts between state interests and local livelihood needs.

New federal legislation proposes to reduce greenhouse gas (GHG) emissions associated with biofuel production. To comply, existing corn ethanol plants will have to invest in new more carbon efficient production technology such as dry fractionation. However, this will be challenging for the industry given the present financial environment of surplus production, recent profit declines, numerous bankruptcies, and lender imposed covenants. This study examines a dry-mill ethanol firm's ability to invest in dry fractionation technology in the face of declining profitability and stringent lender cash flow repayment constraints. Firm level risk aversion also is considered when determining a firm's willingness to invest in dry fractionation technology. A Monte Carlo simulation model is constructed to estimate firm profits, cash flows, and changes in equity following new investment in fractionation to determine an optimal investment strategy. The addition of a lender-imposed sweep, whereby a percentage of free cash flow is used to pay off extra debt in high profit years, reduces the firm's ability to build equity and increases bankruptcy risk under investment. However, the sweep increases long-run equity because total financing costs are reduced with accelerated debt repayment. This thesis shows that while ethanol firm profits are uncertain, the lender's imposition of a sweep combined with increased profit from dry fractionation technology help the firm increase long-run financial resiliency.

Thesis (Doctor of Engineering in Chemical Engineering)--Cape Peninsula University of Technology, 2017.
The search for alternatives to fossil fuel is necessary with a view to reducing the negative environmental impact of fossil fuel and most importantly, to exploit an affordable and secured fuel source. This study investigated the viability of municipal solid waste gasification for a fuel cell system. Potential solid fuels obtained from the study in the form of refuse-derived fuel (RDF) had high heating value (HHV) between 18.17 MJ/Kg - 28.91 MJ/Kg with energy density increased from 4142.07 MJ/m3 to 10735.80 MJ/m3. The molecular formulas of RDF derived from Ladies Smith drop-off site, Woodstock drop-off site and an average molecular formula of all thirteen municipal solid waste (MSW) disposal facilities were CH1.43O1.02, CH1.49O1.19, and CH1.50O0.86 respectively. The comparative ratios of C/H were in the range of 7.11 to 8.90. The Thermo Gravimetric Analysis showed that the dehydration, thermal decompositions, char combustions were involved in the production of gaseous products but flaming pyrolysis stage was when most tar was converted to syngas mixture. The simulation of RDF gasification allowed a prediction of the RDF gasification behaviour under various operating parameters in an air-blown downdraft gasifier. Optimum SFR (steam flowrate) values for RDF1, RDF2 and RDF3 were determined to be within these values 2.80, 2.50 and 3.50 and Optimum ER values for RDF1, RDF2 and RDF3 were also determined to be within these values 0.15, 0.04 and 0.08. These conditions produced the desired high molar ratio of H2/CO yield in the syngas mixture in the product stream. The molar ratios of H2/CO yield in the syngas mixture in the product stream for all the RDFs were between 18.81 and 20.16. The values of H2/CO satisfy the requirement for fuel cell application. The highest concentration of heavy metal was observed for Al, Fe, Zn and Cr, namely 16627.77 mg/Kg at Coastal Park (CP), 17232.37 mg/Kg at Killarney (KL), 235.01 mg/Kg at Tygerdal (TG), and 564.87 mg/Kg at Kraaifontein (KF) respectively. The results of quantitative economic evaluation measurements were a net return (NR) of $0.20 million, a rate of return on investment (ROI) of 27.88 %, payback time (PBP) of 2.30 years, a net present value (NPV) of $1.11 million and a discounted cash flow rate of return (DCFROR) of 24.80 % and 28.20 % respectively. The results of the economic evaluations revealed that some findings of the economic benefits of this system would be viable if costs of handling MSW were further quantified into the costs analysis. The viability of the costs could depend on government responsibility to accept costs of handling MSW.

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

Using crops for fuel generates concerns over competition with food uses. As Rajagopal et al (2009) asserts, “In 2008 the world entered a food crisis amid record-high commodity and energy prices that induced hunger and political unrest in developing countries, by export restrictions in top grain-producing countries”. This took place at the same time when biofuel production, reached its pinnacle in developed countries. This paper examines the effect that biofuel prices and or production has had on food prices in Brazil and U.S. by employing the panel cointegration and Dynamic Ordinary Least Squares (DOLS) method of analysis. In regressing food prices as a function of demand and supply factors, such as oil prices, biofuel prices, interest rates and biofuel production, the study found that the increase in biofuels production over the past eighteen years has had a significant impact on food prices. Over the period January 1995- December 2013, the study estimates that a one hundred percent increase in biofuels production across time and between countries results in the increase of food prices by 21,9%. The study therefore rejects the null hypothesis that states, biofuel production does not have a statistically significant negative impact on food prices in U.S. and Brazil. , and accepts the alternative that biofuel production does have a statistically significant negative impact on food prices in U.S. and Brazil. Other predictors of food prices that the study revealed as significant were oil and interest rates. Policy recommendations for other countries like South Africa are therefore, made based on the results obtained.

Renewability and the carbonaceous basis of biomass provide potential for both energy and chemical production in biorefineries in a fashion similar to crude oil refineries. Biorefineries are envisaged as having a key role in the transition to a more sustainable industry, especially as a means to mitigate greenhouse gas (GHG) emissions. A biorefinery is a concept for the flexible, efficient, cost-effective and sustainable conversion of biomass through a combination of process technologies into multiple products. This implies that biorefineries must be integrated through designs that exploit the interactions between material and energy streams. The wide range of possibilities for biomass feedstock, processes and products poses a challenge to biorefinery design. Integrating biorefineries within evolving economic and environmental policy contexts requires careful analysis of the configurations to be deployed from early in the design stage. This research therefore focuses on the application and development of methodologies for biorefinery design encompassing process integration tools, economic and environmental sustainability analyses together. The research is presented in the form of papers published or submitted to relevant peer-reviewed journals, with a preamble for each paper and a final synthesis of the work as a whole. In a first stage, mass pinch analysis was adapted into a method for integration ofbiorefineries producing bioethanol as a final product and also utilising bioethanol asa working fluid within the biorefinery. The tool allows targeting minimum bioethanol utilisation and assessing network modifications to diminish revenue losses. This new application could stimulate the emergence of similar approaches for the design of integrated biorefineries. The thesis then moves to combine feedstock production models, process simulations in Aspen Plus® and process integration with LCA, to improve energy efficiency and reduce GHG emissions of biorefineries. This work, presented via two publications covering wheat to bioethanol and Jatropha to biodiesel or green diesel, provided evidence of the benefits of biorefinery integrationfor energy saving and climate change adaptation. The multilevel modelling approach is then further integrated into a methodologydeveloped for the combined evaluation of the economic potential and GHG emissions saving of a biorefinery from the marginal performances of biorefineryproducts. The tool allows assessing process integration pathways and targeting forpolicy compliance. The tool is presented via two further publications, the first drawing analogies between value analysis and environmental impact analysis inorder to create the combined Economic Value and Environmental Impact (EVEI)analysis methodology, the second extending this to demonstrate how the tool canguide judicious movement of environmental burdens to meet policy targets. The research embodied in this thesis forms a systematic basis for the analysis andgeneration of biorefinery process designs for enhanced sustainability. The toolspresented will facilitate both the implementation of integrated biorefinery designsand the cultivation of a community of biorefinery engineers for whom suchintegrated thinking is their distinctive and defining attribute.

Thesis (MScEng (Industrial Engineering))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: The world is facing an energy crisis with worldwide energy consumption rising at an alarming rate. The effects that fossil fuels have on the environment are also causing concern. For these two reasons the world is determined to find ‘cleaner’, renewable and sustainable energy sources. The Cape Winelands District Munisipality (CWDM) area has been identified as the study area for a bioenergy project. The CWDM project aims to determine the possibility of producing bioenergy from lignocellulosic biomass, and transporting it as economically as possible to a number of electricity plants within the study area. From the CWDM project a number of research topics were identified. The aim of this thesis is to determine the best location for one or more processing plants that will maximise the potential profit through the entire system. This is achieved by minimising the overall life cycle cost of the project. It takes into account costs from establishing and maintaining the crops, harvesting, transportation, conversion and generation; with a strong focus on the transport costs. In conjunction with a Geographical Information Systems (GIS) specialist and taking into account various factors such as electricity demand, heat sales and substation locations, 14 possible plant locations were identified. The possible supply points for each of the 14 plant locations were then analysed by GIS again to yield data in terms of elevation, road distances and slope. The transport costs were calculated using the Vehicle Cost Schedule (VCS) from the Road Freight Association (RFA) and fuel consumption calculations. It takes into account slope, laden and unladen transport and considers different transport commodities. These calculations together with the other associated costs of the life cycle are then combined with the results of the GIS into an EXCEL file. From this a transportation optimisation model is developed and the equivalent yearly life cycle cost of each of the 14 demand points are minimised by means of LINGO software. Initially runs were done for 2.5 MW capacity plants. From the high profit areas identified here, a single area was chosen and further runs were done on it. These runs were performed to determine the effect of different plant capacities on the life cycle costs, as well as how it affects the farm gate price that can be paid to the farmer. It also determined the effect of farmer participation at different plant capacities. The results indicate that it is currently possible to pay a farmer between R 300.00 and R 358.00 for a ton of biomass. It also revealed that with higher participation from farmers in the CWDM project, lower costs and higher farm gate prices will result, since the transport costs will be lower. Although all the costs within the life cycle are variable over time, the transport cost is the only cost that varies spatially and this will have a major effect on the overall system cost. The thesis found that generating electricity from woody biomass is feasible for all areas that were considered as well as for all variations considered during the sensitivity analysis. For the recommended plant size of 5 MW the transport of logs will be optimum.
AFRIKAANSE OPSOMMING: Die tempo waarteen energieverbruik wêreldwyd styg is ʼn rede tot kommer. Die nadelige effek wat fossiel brandstowwe op die omgewing het, is ook ʼn probleem. Hierdie twee redes is hoofsaaklik wat die wêreld dryf om ‘skoner’ hernieubare en volhoubare energie bronne te vind. Die Kaapse Wynland Distrik Munisipaliteit (KWDM) area is identifiseer as ʼn studie area vir ʼn bio-energie projek. Die doel van die KWDM projek is om die vervaardiging van bio-energie vanaf plantasies, die vervoer van hierdie bome sowel as die prosessering koste by die fabriek te bepaal en te evalueer. Vanuit die KWDM projek het `n aantal tesisse ontwikkel waarvan hierdie een is. Die doel van hierdie tesis is om die beste posisie vir een of meer prosesserings fabrieke te bepaal wat die potensiële wins van die KWDM projek sal maksimeer. Dit is ook gemik daarop om die ekwivalente jaarlikse oorhoofse lewenssiklus koste van die projek te minimeer. Dit neem die vestiging en onderhoud van gewasse, oeskostes, vervoerkostes en proseskostes in ag, met ʼn spesifiek fokus op die vervoerkoste. In samewerking met `ʼn “Geographical Information Systems” (GIS) spesialis en deur verskeie faktore, soos elektrisiteitsverbruik, inkomste vanaf hitte verkope en substasie posisies, in ag te neem is 14 moontlike fabriek posisies identifiseer. Verder is die moontlike voorsienings areas van elk van die 14 fabriek posisies weer deur GIS analiseer om resultate in terme van hoogte bo seespieël, padafstand en helling te verkry. Die vervoerkostes is verkry vanaf die “Vehicle Cost Schedule” (VCS) van die “Road Freight Association” (RFA), asook berekeninge wat die brandstof verbruik in ag neem. Hierdie kostes sluit in die effek van gradiënt, gelaaide en ongelaaide vervoer sowel as verskillende vervoer produkte. Hierdie berekeninge sowel as die ander kostes in die siklus en die resultate van GIS is kombineer in ʼn EXCEL leer. Hierdie data word dan gebruik om ʼn LINGO model te ontwikkel en die oorhoofse lewenssiklus koste van elk van die 14 fabriek posisies te minimeer. Optimering is gedoen vir 2.5 MW kapasiteit fabrieke. Uit die beste areas is een area identifiseer en verdere lopies is daarop gedoen. Die doel van hierdie lopies is om die effek van verskillende fabriekskapasiteit op die lewensiklus koste te bepaal, asook die effek daarvan op die prys wat aan die boer betaal word vir hout. Hierdie lopies is ook gebruik om die effek van boer deelname te bepaal. Die resultaat dui aan dat dit tans moontlik is om ʼn boer tussen R 300.00 en R 358.00 te betaal vir ʼn ton biomassa. Dit het ook gewys dat hoe meer boere deelneem aan hierdie projek hoe laer is die oorhoofse lewensiklus koste en hoe hoër is die prys wat betaal kan word vir hout aangesien die vervoerkoste laer sal wees. Alhoewel al die lewensiklus kostes veranderlik is oor tyd, is dit net die vervoerkoste wat ʼn ruimtelike komponent ook het en dit sal ʼn groot effek op die oorhoofse lewenssiklus koste hê. Die tesis bevind dat dit lewensvatbaar is vir alle areas in die studie om elektrisiteit op te wek vanaf hout biomassa, selfs al word die uiterse variasie in die sensitiwiteitsanalise gebruik. Vir die aanbeveling van ʼn 5 MW fabriek sal die goedkoopste vervoer opsie boomstompe wees.

Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: The discussion on climate change is leading to a re-evaluation of tree plantations in South Africa; prompting the adoption of forest bioenergy system as one of the cost effective ‘carbon mitigation options’. In an analysis of this changing paradigm, emphasis was placed on the socio-economic aspects of integrated commercial tree plantations and forest bioenergy systems with special attention to harvest residues recovery for bioelectricity production and construction and operation of a bioelectricity plant. The study also explored the direct and indirect benefits that adjacent communities derive from tree plantations in South Africa in order to determine the potential impact of integrated timber and bioelectricity production on rural livelihood and conventional forestry operations. Structured questionnaires and in-depth interviews were used in randomly sampling twelve villages on Mondi tree plantations in the Piet Retief and Iswepe areas of South Africa. Six villages from each area were selected; and a systematic random sampling of ten households per village was carried out. The possibility of using harvest residues from final clear felling from these plantations for bioelectricity production was examined. The study developed and described a scenario for a five megawatt bioelectricity generation facility, requiring an annual volume of 19,569.85 dry tonnes of residues as feedstock for its operation. The study revealed that adjacent rural communities to Mondi plantations in Piet Retief and Iswepe areas enjoy direct benefits such as employment opportunities, utilization of harvest residues, utilization of non-timber resources, and free accommodation. Indirect benefits that these communities enjoy include: free farmland and graze-land and various social benefits. Issues of concern and dislike such as: lack of electricity; poor health and sanitation and transportation problems were also identified. Using NPV and IRR, the study estimated the economic impacts of integrated pulpwood and bioelectricity production, compared to conventional pulpwood production operation. The study concluded that integrated pulpwood and harvest residue recovery for bioelectricity production is a profitable means of producing renewable energy. The approach was found to increase the profitability of conventional forest operations.
AFRIKAANSE OPSOMMING: Besprekings rondom klimaatsverandering lei tot ‘n her-evaluasie van boom plantasies in Suid Afrika wat aanleiding gee tot die aanvaarding van bio-energie stelsels as een van die koste effektiewe “koolstof versagtende opsies”. In ‘n ontleding van hierdie paradigma verandering, is klem geplaas op die sosio-ekonomiese aspekte van die integrasie van boom plantasies en bos bio-energie stelsels. Spesiale aandag is gegee aan onginningsafval herwinning vir bio-energie produksie en die konstruksie en werking van ‘n bio-elektriese kragsentrale. Die studie ondersoek ook die direkte en indirekte voordele wat gemeenskappe, aangrensend aan boom plantasies in Suid Afrika verkry, om sodoende die potensiële effek van geintegreerde hout en bio-elektriese produksie op landelike lewensbestaan en konvensionele bosbou operasies te bepaal. Gestruktureerde vraelyste en indiepte onderhoude is gebruik om ‘n lukraakte steekproef van twaalf dorpies op Mondi boom plantasies in die Piet Retief en Iswepe areas van Suid Afrika uit te voer. Ses dorpies in elke area is gekies en ‘n sistematiese lukraakte steekproef van tien huishoudings per dorpie is uitgevoer. Die moontlikheid om ontginningsafval van finale kaalkap van hierdie plantasies vir bio-elektrisiteit te gebruik is ook ondersoek. Die studie het ‘n senario ontwikkel en beskryf van ‘n vyf megawatt bio-elektriese kragsentrale wat ‘n jaarlikse volume van 11,708 droë ton ontginningsafval benodig as voermateriaal vir kragopwekking. Die studie het getoon dat aangrensende landelike gemeenskappe langs Mondi plantasies in die Piet Retief en Iswepe areas direkte voordele soos werksgeleenthede, gebruik van ontginningsafval, gebruik van nie-hout hulpbronne en gratis akkommodasie geniet. Indirekte voordele wat gemeenskappe geniet sluit in gratis toegang to landbou grond en weiding, sowel as sosiale voordele. Probleemfaktore waarmee hulle saamleef is ‘n gebrek aan elektrisiteit, swak gesondheids en sanitasie dienste en vervoerprobleme. Deur die gebruik van NPV en IRR analitiese metodes is die ekonomiese impak van geintegreerde pulphout en bio-elektrisiteits produksie bepaal en vergelyk met konfensionele pulphout produksie. Die gevolgtrekking is dat geintegreerde pulphout en ontginningsafval herwinning vir bio-elektrisiteit produksie ‘n winsgewende manier van hernubare energie produksie is. Die benadering kan die winsgewendheid van konfensionele bosbou operasies verbeter.

Bioethanol is likely to be a large contributor to the fuel sector of industry in the near future. Current research trends are geared towards utilizing food crops as substrate for bioethanol fermentation; however, this is the source of much controversy. Utilizing food crops for fuel purposes is anticipated to cause massive food shortages worldwide. Cellulose is the most abundant renewable resource on earth and is subject to a wide array of scientific study in order to utilize the glucose contained within it. Waste paper has a high degree of cellulose associated with it, which makes it an ideal target for cellulose biotechnology with the ultimate end goal of bioethanol production. This study focussed on producing the necessary enzymes to hydrolyse the cellulose found in waste paper and using the sugars produced to produce ethanol. The effects of various printing inks had on the production of sugars and the total envirorunental impact of the effluents produced during the production line were also examined. It was found that the fungus Trichoderma longibrachiatum DSM 769 grown in Mandel's medium with waste newspaper as the sole carbon source at 28 °C for 6 days produced extracellular cellulase enzymes with an activity of 0.203 ± 0.009 FPU.ml⁻¹, significantly higher activity as compared to other paper sources. This extracellular cellulase was used to hydrolyse waste newspaper and office paper, with office paper yielding the highest degree of sugar production with an end concentration of 5.80 ± 0.19 g/1 at 40 °C. Analysis by HPLC showed that although glucose was the major product at 4.35 ± 0.12 g/1, cellobiose was also produced in appreciable amounts (1.97 ± 0.71 g/1). The sugar solution was used as a substrate for Saccharomyces cerevisiae DSM 1333 and ethanol was produced at a level of 1.79 ± 0.26 g/1, the presence of which was confirmed by a 600 MHz NMR spectrum. It was found that cellobiose was not fermented by this strain of S. cerevisiae. Certain components of inks (the PAHs phenanthrene and naphthalene) were found to have a slight inhibitory effect (approximately 15% decrease) on the cellulase enzymes at very high concentrations (approximately 600 μg/1 in aqueous medium), while anthracene had no effect. Whole newsprint ink was shown not to sorb glucose. The environmental analysis of the effluents produced showed that in order for the effluents to be discharged into an aqueous ecosystem they would have to be diluted up to 200 times. They were also shown to have the potential to cause severe machinery damage if reused without proper treatment.

A mixed integer programming model is developed to determine a logistical design for maximizing rates of return to harvest, storage, transportation, and bioreflning of herbaceous crop residue for production of biofuels and feed for ruminant animals. The primary objective of this research is to identify the optimal location, scale, and number of pretreatment and biorefinery plants in northeastern North Dakota. The pretreatment and biorefinery plants are modeled under the assumption that they utilize recent technological advancement in AFEX and Simultaneous Saccharification and Fermentation, respectively. Potential feedstocks include wheat straw, barley straw, Durum straw, and com stover. Results indicate that the minimum ethanol rack price that will effectively trigger the production of cellulosic ethanol is $1.75 per gallon.

Thesis (MScEng)-- Stellenbosch University, 2013.
ENGLISH ABSTRACT: Climate change that results from greenhouse gases (GHG’s) released from the burning of fossil fuels, together with the rising price of oil, have sparked interest in renewable biofuels. The production of biofuels also presents potential socio-economic benefits. There are two types of technologies for bioethanol production: · First generation bioethanol is produced from food feedstocks such as juice of sugarcane. · Second generation bioethanol is produced from non-food feedstocks (lignocellulosic materials). This project is concerned with 1st and 2nd generation bioethanol production from sugarcane juice and bagasse and the integration of these technologies. This project comprises a combination of experimental and process modelling work to assess energy efficiencies and the economic viability of integrated and stand-alone processes in the sub-Saharan African context. First generation fermentation experiments were conducted and high ethanol concentrations of up to 113.7 g/L were obtained. It was concluded that a recombinant yeast strain may be able to replace a natural hexose fermenting yeast for 1st generation fermentations to reduce costs. 2nd generation fermentation experiments were performed and ethanol concentrations of close to 40 g/L were obtained. Combinations of 1st and 2nd generation fermentation experiments were performed to improve the 2nd generation fermentation. In one of the experiments it was concluded that the combination of 1st and 2nd generation fermentations significantly improved the 2nd generation fermentation with an overall ethanol concentration of 57.6 g/L in a shorter time than for the pure 2nd generation experiments. It was determined from washing and pressing experiments that pressing the pre-hydrolysate liquor out of the pre-treated bagasse will sufficiently lower the levels of inhibitors in a 2nd generation fermentation when using a hardened yeast. Some of the data from the 1st generation experiments were used along with literature data to model a first generation process in Aspen Plus® which processes 493 tons of cane per hour (tc/hr). Pinch heat integration was used to reduce the utility requirements. The process used the bagasse that was generated to co-produce steam and electricity. The excess electricity was sold for additional revenue. In one scenario the excess bagasse was determined at 57.5%. This bagasse was sold to a stand-alone 2nd generation plant. The first generation process produced 85.5 litres of ethanol per ton of cane (L/tc), the integrated process produced 128 L/tc while the stand-alone 2nd generation process produced 185 litres of ethanol per ton of bagasse (50% moisture) or 25.5 L/tc. The amount of excess electricity that was produced ranged from 14.3 to 70.2 kWh/tc. Economic analyses were performed using South African economic parameters to resemble the sub- Saharan African context. Data from the 1st generation process model and literature data for integrated 1st and 2nd generation and stand-alone 2nd generation processes were used for the analyses. It was found that the integrated plant is the most economically viable (IRR = 11.66%) while the 1st generation process basically broke even (IRR = 1.62%) and the 2nd generation process is unviable. This was as a result of high sugarcane prices and too few incentives for 2nd generation ethanol.
AFRIKAANSE OPSOMMING: Klimaatsverandering wat veroorsaak word deur kweekhuisgasse wat vrygestel word deur die verbranding van fossielbrandstowwe en die stygenede olieprys het belangstelling in hernubare biobrandstowwe laat opvlam. Die produksie van biobrandstowwe hou ook potensiële sosioekonomiese voordele in. Daar is twee tegnologieë vir bioetanol produksie: · Eerste generasie bioetanol word vanaf voedsel bronne soos suikersap geproduseer. · Tweede generasie bioetanol word van nie-voedsel bronne (lignosellulose materiaal) geproduseer. Hierdie projek handel oor 1ste en 2de generasie bioetanol produksie van suikersap en suikerriet bagasse en die integrasie van hierdie tegnologieë. Hierdie projek bestaan uit ‘n kombinasie van eksperimentele- en prosesmodellering werk om die energiedoeltreffendheid en ekonomise vatbaarheid van geïntegreerde en alleenstaande prosesse in die sub-Sahara konteks te ondersoek. Eerste generasie fermentasie eksperimente is uitgevoer en hoë etanol konsentrasies van tot 113.7 g/L is gekry. Dit was bepaal dat ‘n rekombinante gisras ‘n natuurilke heksose fermenterende gisras kan vervang vir 1ste generasie fermentasies om kostes te bespaar. 2de generasie fermentasie eksperimente is gedoen en etanol konsentrasies van amper 40 g/L is behaal. Kombinasies van 1ste en 2de generasie fermentasie-eksperimente was uitgevoer om die 2de generasie fermentasie te verbeter. In een van die eksperimente is dit bepaal dat die kombinasie van 1ste en 2de generasie fermentasie die 2de generasie fermentasie beduidend verbeter het met ‘n etanol konsentrasie van 57.6 g/L en dít in ‘n korter tyd as vir die suiwer 2de generasie eksperimente. Dit was bepaal vanuit pers- en was eksperimente dat om die pre-hidrolisaat vloeistof uit die stoombehandelde bagasse te pers, die vlak van inhibitore in ‘n 2de generasie fermentasie voldoende verlaag vir die gebruik van ‘n verharde gis. Van die data van die 1ste generasie eksperimente was saam met literatuurdata gebruik om ‘n 1ste generasie proses in Aspen Plus® te modelleer wat 493 ton suikerriet per uur prosesseer (tc/hr). Pinch hitte integrasie was gebruik om die dienste vereistes te verminder. In die proses word die bagasse gebruik om stoom en elektrisiteit te genereer. In een geval was die oortillge bagasse bepaal as 57.5%. Hierdie bagasse was verkoop aan ‘n alleenstaande 2de generasie aanleg. Die eerste generasie proses het 85.5 liter etanol per ton suikerriet geproduseer (L/tc), die geïntegreerde proses het 128 L/tc geproduseer terwyl die 2de generasie proses 185 liter etanol etanol per ton bagasse (50% vog) of 25.5 L/tc geproduseer het. Die hoeveelhede oortillige elektrisiteit wat geproduseer is wissel van 14.3 tot 70.2 kWh/tc. Ekonomiese analieses is gedoen met Suid-Afrikaanse ekonomiese parameters om die sub-Sahara Afrika-konteks uit te beeld. Data van die 1ste generasie prosesmodel en literatuurdata van geïntegreerde 1ste en 2de generasie en alleenstaande 2de generasie prosesse was vir die analieses gebruik. Dit is bepaal dat die geïntegreerde model die mees ekonomies vatbare model is (IRR = 11.66%) terwyl die 1ste generasie proses basies gelyk gebreek het (IRR = 1.62%) en die 2de generasie proses is ekonomies onvatbaar. Hierdie bevindinge is as gevolg van hoë suikerrietpryse en te min aansporings vir 2de generasie etanol.

Gasification is a thermo-chemical process which transforms biomass into valuable synthesis gas. Integrated with a biorefinery it can address the facility’s residue handling challenges and input demands. A number of feedstock, technology, oxidizer and product options are available for gasification along with combinations thereof. The objective of this work is to create a systematic method for optimizing the design of a residual biomass gasification unit. In detail, this work involves development of an optimization superstructure, creation of a biorefining scenario, process simulation, equipment sizing & costing, economic evaluation and optimization. The superstructure accommodates different feedstocks, reactor technologies, syngas cleaning options and final processing options. The criterion for optimization is annual worth. A biorefining scenario for the production of renewable diesel fuel from seed oil is developed; gasification receives the residues from this biorefinery. Availability of Soybeans, Jatropha, Chinese Tallow and woody biomass material is set by land use within a 50-mile radius. Four reactor technologies are considered, based on oxidizer type and operating pressure, along with three syngas cleaning methods and five processing options. Results show that residual gasification is profitable for large-scale biorefineries with the proper configuration. Low-pressure air gasification with filters, water-gas shift and hydrogen separation is the most advantageous combination of technology and product with an annual worth of $9.1 MM and a return on investment of 10.7 percent. Low-pressure air gasification with filters and methanol synthesis is the second most advantageous combination with an annual worth of $9.0 MM. Gasification is more economic for residue processing than combustion or disposal, and it competes well with natural gas-based methanol synthesis. However, it is less economic than steam-methane reforming of natural gas to hydrogen. Carbon dioxide credits contribute to profitability, affecting some configurations more than others. A carbon dioxide credit of $33/t makes the process competitive with conventional oil and gas development. Sensitivity analysis demonstrates a 10 percent change in hydrogen or electricity price results in a change to the optimal configuration of the unit. Accurate assessment of future commodity prices is critical to maximizing profitability.

Thesis (M. Sc.)--University of Alberta, 2009.
Title from pdf file main screen (viewed on July 10, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Department of Mechanical Engineering, University of Alberta." Includes bibliographical references.

A research report submitted to the Faculty of Science, University of the Witwatersrand, in partial fulfillment of the requirement for the degree of Master in Environmental Science Johannesburg, 2015
Quantifying ecosystem services of urban forests has become an important subject for the national and international ecological economics agenda. This is in the wake of offsetting anthropogenic emissions of CO2, while promoting urban habitability and sustainability. This study estimates above-ground tree biomass, carbon stored and the associated economic value and net economic value of carbon sequestrated by the tree planting project in Soweto, Johannesburg, South Africa. Measurements of diameter at breast height (1.3 m) and tree height were done on all the individual trees that were recently planted (estimated to be about seven years) and other trees estimated to be over 25 years old in Petrus Molefe Park and Thokoza Park. A general allometric equation by Tietema (1993) was used to estimate above-ground biomass which was converted to carbon stocks. The economic value of carbon sequestrated was calculated at an equivalent price of R440.40 per tonne of carbon. The total above-ground biomass, carbon stored and economic value, and net economic value of the trees in Petrus Molefe Park was 7.45 tonnes, 3.35 tonnes, R1,475 and R-495,325, while the trees in Thokoza Park had 205.76 tonnes, 92.59 tonnes, R40,777 and R-312,023, respectively. The results indicated that the older trees in Thokoza Park had larger amounts of above-ground tree biomass, greater carbon storage and net economic value than the younger trees in Petrus Molefe Park. The economic values of carbon sequestrated were less than the cost of planting the trees, therefore the net economic value of carbon sequestrated were negative. The project is at an early, but promising stage, since the Greening Soweto Project provided a number of ecosystem services (i.e. beautifying the landscape, filtering air, recreation and amenity etc.), the performance of the project was evaluated by the extent to which it integrates the environmental and social benefits into the economic benefits and opportunities. Key words: Above-ground biomass, allometric equation, carbon stored, diameter at breast height, net economic value.

M.A.
Although South Africa is a country endowed with abundant energy resources (fuels such as coal, uranium and gas), biomass is the prime source of energy for cooking and heating in the rural domestic sector. Fuelwood is the common biomass used, followed by crop residues and animal dung. This research examines the environmental and socio-economic impacts of biomass energy consumption in the Mbhokota village in the Northern Province. The research was conducted by means of a field survey. Data collection methods included administering questionnaires to those who are involved in fuelwood collection (mostly women), interviews with various interested groups and personal observation of the affected sites, and a review of literature relevant to this study. The use of biomass as a source of fuel has much wider implications for the social and biophysical environments. The excessive cutting of trees for fuel leads to a reduction in the diversity of plant species and destruction of habitat for wildlife. Loss of soil cover through the use of crop residues increases soil erosion and thus reduces the agricultural production. The use of biomass fuels gives rise to high levels of indoor air pollution which affects the health of people. As fuelwood supplies diminish, people must travel further and hence spend more time collecting wood. Greater time spent collecting wood means that less time is spent on food production and other household activities (farming, childcare, housekeeping, socialising and educating themselves). Other issues of concern include the high cost of purchasing wood from vendors and personal security in places where wood is collected. The above factors do not only entrench poverty, but also have dire implications for the rural economy. This study has shown that the present patterns of fuelwood collection inflict permanent damage on the environment, reducing its ability to provide further fuel in the future. The implication is that the supply of fuelwood can no longer be guaranteed in some parts of the study area, leading to the use of crop residues and animal dung. This report also highlights the recommendations and management measures (based on the results of the study) that can be used in mitigating the impacts of biomass energy use. These include the introduction of improved stoves, use of solar energy as an alternative energy source, empowerment of women, establishment of community based projects and integrating energy with rural development

Recent years have seen an unprecedented global increase in the production and use of biofuels. This has been driven primarily by government support for biofuel industries. Soybeans are the only field crop produced in sufficient quantities in the province of KwaZulu- Natal (KZN) that the South African (SA) industrial biofuel strategy identifies as a potential biodiesel feedstock. Thus, this study is an evaluation of the economic feasibility of producing biodiesel on farms from soybeans in the main soybean-producing regions of KZN, using batch processing biodiesel plants. A mixed integer linear programming model was developed to simulate observed agricultural land rental rates (estimated at 4.48% of the market value of land) and cropping behaviour of commercial crop farms in the study regions. The model incorporates various alternative crops, crop rotations, tillage techniques, arable land categories and variance-covariance matrices to account for risk in production. All data are on a real 2009/10 basis. The model is used to predict possible farmer investment behaviour and determine the minimum biodiesel subsidy required to stimulate soybean-based biodiesel production in the study areas. Results suggest that biodiesel production is currently not an economically viable alternative to fossil fuel, and that the incentives and commitments outlined by the current industrial biofuel strategy are inadequate to both establish and sustain a domestic biodiesel industry. Under baseline assumptions, a realistic minimum implicit subsidy of R4.37 per litre of biodiesel is required to draw soybean-based biodiesel production into the optimum solution for commercial farms. The economic feasibility of on-farm biodiesel production is highly dependent on the soybean price (i.e., the feedstock input cost) and the soybean oilcake price (i.e., the highest valued byproduct). Thus, future promotion of biodiesel ventures could primarily target a reduction of feedstock costs through the development of new technologies which increase yields of available feedstocks and/or permit the use of lower cost alternatives. Higher subsidy levels are anticipated for: (i) small-scale initiatives (particularly in the absence of a rental market for cropland); (ii) soybean-based biodiesel production in areas with less suitable growing conditions for cultivating soybeans; and (iii) using sunflower and/or canola as biodiesel feedstock. To the author’s knowledge no other previous studies have attempted to quantify the minimum level of support needed to stimulate biodiesel production in South Africa. The SA industrial biofuels strategy promotes a development-oriented strategy with feedstock produced by smallholders and processed by traditional producer-owned cooperatives. However, traditional cooperatives suffer from a myriad of institutional problems that are associated with ill-defined property rights. As such, it is argued that these initiatives will fail to attract the capital and expertise needed to process biodiesel. This research, therefore, highlights the need for South Africa’s current Cooperatives Act to be amended. Accordingly, this also infers a need to revise the proposed SA industrial biofuels strategy. It is concluded that smallholder participation in biodiesel ventures would require a rental market for cropland, co-ownership of the processing plant in a non-traditional cooperative or investor-owned firm, information and training, and a high level of government subsidy. This research advocates that government consider promoting soybean oil extrusion ventures as a means of stimulating rural development for small-scale farming initiatives rather than soybean-based biodiesel production, as they will likely require less government assistance, whilst potentially combating the food versus fuel debate against biofuels. This is compounded by the fact that South Africa has historically been a net importer of both soybean oilcake and soybean oil. Importantly, however, the proliferation of such initiatives should not be based on the current notion of traditional cooperatives. The need for government to play a proactive role in such ventures through facilitating the development of appropriate business models which stimulate private investment in feedstock and processing facilities is clearly evident.
Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

D. Tech. Business Administration
The study attempts to identify and quantify socio-economic factors that are influence the production and distribution of biofuels products in Zimbabwe. It also seeks to provide an empirical analysis of the importance of stakeholders in Biofuel production and distribution and how their perceptions and influences tend to affect production and distribution.

Dissertação de Mestrado em Energia para a Sustentabilidade apresentada à Faculdade de Ciências e Tecnologia
O estilo de vida actual exige um crescente consumo de energia que conduz a uma depleção acelerada de recursos naturais.A utilização intensiva de combustíveis fósseis afasta-nos cada vez mais de uma situação sustentável em termos de fontes energéticas, originando consequências gravosas em relação à poluição do planeta, nomeadamente, através do efeito estufa, o que tem provocado alterações climáticas claramente já bem perceptíveis.A procura de fontes sustentáveis de energia é pois um tema de maior relevância da actualidade e a razão de ser desta tese.O estudo desta dissertação tem como objetivo analisar o potencial de produção e a viabilidade económica de exploração dos recursos lenhocelulósicos da biomassa residual da palha de cana-de-açúcar no Brasil, e da biomassa florestal residual em Portugal. A segunda geração de biocombustíveis, especificamente a produção gás natural sintético através da gaseificação foi o caminho escolhido, com a suposta unidade trabalhando sozinha e anexada a uma fábrica de papel e celulose, analisando seus respectivos desempenhos nas duas regiões.Para as duas regiões considerou-se cinco capacidades diferentes de processamento, nomeadamente, 10, 50, 100, 200 e 300 MWth.Dado que o potencial de disponibilidade de biomassa dos dois países é muito díspar, calculou-se também a área necessária em hectares para os cinco cenários de produção. Em termos de análise económica considerou-se os indicadores de valor actual liquido (VAL), taxa interna de retorno (TIR) e payback descontado (PBD), com valores de taxas de juros ajustadas aos países em causa. Assim tomaram-se os valores de 6, 8 e 12,15% para o Brasil e 2, 4 e 6% para Portugal.No sentido de tornar a rota de conversão (gaseificação) mais atrativa, e como sugestão aos agentes de decisão, discutiu-se e elaborou-se uma possível política de incentivos, baseada em subsídios.Ao final do trabalho conclui-se que o cenário Brasileiro em termos de disponibilidade de biomassa e área a se explorar é muito maior que e o de Portugal, mas em termos económicos Portugal leva larga vantagem para um eventual investimento, devido às baixas taxas de juros que são trabalhadas no país.Contudo a rota de produção de gás natural sintético através da gaseificação ainda está em um estágio muito prematuro de desenvolvimento, necessitando de massivo investimento em I&D e incentivos governamentais para se tornar uma rota consolidada de produção na segunda geração de biocombustíveis.
The current lifestyle requires an increasing energy consumption that leads to an accelerated depreciation of natural resources.The intensive use of fossil fuels is increasingly taking us out of a sustainable energy source, leading to serious consequences for the planet's pollution, notably through the greenhouse effect, which has brought about clear and noticeable climate change.The search for sustainable sources of energy is therefore a topic of greater relevance today and the main raison of this thesis.The aim of this dissertation is to analyze the production potential and economic feasibility through the exploitation of the lignocellulosic resources from the residual biomass sugarcane straw in Brazil and the residual forest biomass in Portugal.The second generation of biofuels, specifically the production of synthetic natural gas through gasification was the chosen path, with the supposed factory working in two scenarios: alone and attached to a pulp and paper mill, analyzing their respective performances in the two regions.For the two regions five different processing capacities were considered, namely, 10, 50, 100, 200 and 300 MWth.Given that the biomass availability potential of the two countries is very wide, the area required in hectares for the five production scenarios was also calculated.In terms of economic analysis, was considered the indicators of net present value (NPV), internal rate of return (IRR) and discounted payback (DPB), with interest rate adjusted to the countries concerned. Thus, the values of 6, 8 and 12,15% were taken for Brazil and 2, 4 and 6% for Portugal.In order to make the conversion route (gasification) more attractive, and as a suggestion to decision makers, a possible subsidy-based incentive policy was discussed and elaborated.At the end of the study, the results displayed a larger advantage of Brazil over Portugal in terms of biomass for area to be explored, meantime Portugal present a huge advantage over Brazil in economic terms for a eventual investment due the low interest rates worked at the country.However, the natural gas production route through gasification is still at a very early stage of development, requiring massive investment in R & D and government incentives, to become a consolidated route of production in the second generation of biofuels.

Renewable Natural Gas (RNG) is a low-carbon fuel source that is derived from the anaerobic digestion (AD) or thermal gasification (TG) of biomass, or produced using renewable electricity through the methanation of carbon dioxide. This thesis uses a thermodynamic balance to determine the total technical potential of RNG in the United States, as well as the future technical potential of methanation-derived RNG based on growth curves for renewable electricity. Furthermore, this work establishes an analytic decision-making framework for determining on a rolling basis, from an economic standpoint, whether to sell electricity directly to the grid, or produce and sell methanation-derived RNG. This framework is used to establish the economic potential of RNG, based on Texas wind resources. This work details the formulation of a model that determines which production option generates more marginal profit, based on fluctuating electricity and gas prices. The model also aggregates the total amount of electricity and RNG sold, assuming that the main objective is to maximize the marginal profit of integrated wind- and methanation facilities. This work concludes that the annual technical potential of methanation-derived RNG nationally was 1.03 Quads in 2011. The technical potential of biomass-derived RNG was 9.5 Quads. Thus, the total 2011 technical potential of RNG in the United States was 10.5 Quads, or equal to roughly 43% of the total US consumption of natural gas that year. Assuming a constant, 80% electrolyser efficiency, the technical potential of methanation-derived RNG is expected to rise at an average rate of 1.4% per year, following growth curves for renewable power, until the year 2040, when it will be 1.54 Quads. The 2011 economic potential of methanation-derived RNG in Texas was between 2.06×10⁷ MMBTU and 3.19×10⁷ MMBTU, or between 19.4% and 30.1% of the corresponding annual technical potential. Furthermore, the total marginal profit increase from introducing the option of producing and selling methanation-derived RNG was around $366 million, given a ‘best case scenario’ for the state of Texas.
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