Seaweed biomass has been identified as a potential fermentation substrate for third generation biofuel processes due to its high carbohydrate content and its potential for mass cultivation without competing for agricultural land, fresh water and fertilisers. This thesis aimed to develop and advance existing processes to convert brown seaweeds into bioethanol. The main kelp species chosen as biomass candidates were Laminaria digitata, Laminaria hyperborea, Saccharina latissima and Alaria esculenta due to their abundance in Scottish waters and their identified potential for mariculturing. These kelp species were chemically characterised to identify seasonal variations, to recommend suitable seaweed candidates for bioethanol production and predict best harvest times. This has only been demonstrated before on one species - L. digitata. The chemical composition analyses were carried out over a 14 months sampling period, which focused on the storage carbohydrates laminarin and mannitol and the structural carbohydrates alginate, cellulose, fucoidan and xylose. In addition to carbohydrates the protein, nitrogen, carbon, polyphenol, ash and metal content was also profiled. Chemical profiling identified all four kelps as potential fermentation candidates, where maximum carbohydrate contents coincided with lowest ash and polyphenol content, usually seen in autumn. Biomass pre-treatment and saccharification are up-stream processes aimed at enhancing extraction of carbohydrates and converting those into fermentable substrates. Conversion of seaweed biomass into fermentation substrate evaluated acids and enzymes for seaweed pre-treatment and saccharification. Methodologies focused on optimising saccharification yields were developed to identify process critical parameters and develop methods for routine analysis of seaweed biomass. Results demonstrated that dilute acid hydrolysis was were less effective in releasing fermentable sugars, and also resulted in higher salinities compared to enzymatic hydrolysis using hemicellulosic and cellulosic enzymes, which were the preferred method of saccharification. All seaweeds in this thesis were assessed as fermentation substrates using the yeasts S. cerevisiae and P. angophorae, that principally ferment glucose or mannitol, respectively. Small-scale fermentation assays were developed for both yeasts to maximise ethanol yields and achieve process robustness. Both yeasts achieved a maximum ethanol yield of 0.17 g g-1 using Laminaria spp. On the basis of results, S. cerevisiae is recommended as the most useful yeast at this present point for ethanol fermentation from seaweed hydrolysates because of its tolerance to high salinity and ethanol concentrations. As salinity can negatively affect non-halotolerant enzymes, isolation of marine microorganisms was therefore carried out with the aim to highlight their enzymatic potential in seaweed saccharification. This was achieved through the isolation of two members of the genus Pseudoalteromonas, where saccharification yields using crude intracellular enzyme preparations exceeded those of dilute acids. In addition, the fermentative potential of microbial isolates as future ethanologenic strains was also evaluated. Understanding of the metabolic pathways is needed to fully assess the potential of those strains for genetic alteration. In conclusion, this thesis has demonstrated that up to ca. 20 g l-1 of ethanol can be produced from kelp species that grow on the west coast of Scotland. The procedure developed and used to produce ethanol requires further development, specifically the need for ethanol-fermenting microorganisms that can utilize mannitol and alginate; use of marine-adapted enzymes for saccharifiction; and the development of processes to achieve substrate concentration with reduced salinities. Comparison of theoretical ethanol yields from seaweed biomass with ethanol yields from terrestrial crops showed that the complete utilisation of all three major seaweed carbohydrates (laminarin, mannitol and alginate) from kelp species is needed for the process to be able to compete with 1st generation biofuel processes.

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.

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This research forms part of a programme of work at the University of Canterbury investigating the production of liquid fuels from biomass. The drivers for this research are the plentiful supply of woody biomass in New Zealand as well as the necessity for a reduction in the use of fossil fuels. Fischer-Tropsch synthesis has been chosen as the base conversion method for syngas to liquid fuels. While Fischer-Tropsch plants are traditionally very large, the low geographical density of the biomass feedstock necessitates a shift from a traditional economies of scale approach. In this research a sawmill integrated polygeneration scenario is proposed that recognises the synergy between the heat and electrical requirements of a mill and the Fischer-Tropsch process that can supply both as well as liquid fuels. Techno-economic modelling of variations to this polygeneration arrangement were performed using a traditional Fischer-Tropsch slurry reactor as the basis. The breakeven price of syncrude produced in the process based on a 30 year plant life and 10% discount factor was as low as $US 167 per barrel. This arrangement is coupled with development of and experimentation with a microchannel reactor in a further attempt to overcome economies of scale disadvantages. The lab scale microchannel reactor consisted of a shim with 50 channels of 37mm length with 0.2mm height and 0.3mm width. The microchannel reactor was tested with shorter run periods to compare different catalyst washcoats consisting of neat cobalt, cobalt on titania and a combustion synthesis method over a temperature range of 210-240°C at 20 bar. Comparison was also made to a lab scale fixed bed reactor with a powdered cobalt on titania catalyst. The neat cobalt washcoat proved to have the best performance per unit mass of catalyst of the three washcoats. The performance of the microchannel reactor was 32-40 times better per unit catalyst mass than the fixed bed reactor. From data based on the shorter runs the neat cobalt washcoat and the cobalt on titania washcoat were selected for further analysis over longer runs at a range of pressures from 2-20 bar and temperatures from 210-240°C. These runs were each approximately 70 hours long and provided a better analysis of the narrowed catalyst choice. The productivity results of the catalysts were fitted to established kinetic equations from literature with an excellent correlation. More accurate Anderson-Schultz-Flory selectivity values were also obtained ranging between 0.72 to 0.82. This is certainly an area that would warrant further attention as a higher selectivity has a very positive affect on plant economics. Establishment of the kinetic equations for the catalyst performance allowed modelling of reactors with greater volume along with investigation of mass transfer limitations to assist in scale up of the technology. It was found that under 4-5mm hydraulic diameter channel dimensions the mass transfer limitation from the bulk gas phase to the catalyst interface is negligible. A scaled up microchannel reactor concept design is proposed utilising stainless steel mesh folded into 2mm channels to increase catalyst surface area compared to straight shim. A costing correlation was produced per unit of reactor volume to allow a full scale cost of the microchannel reactor to be estimated for inclusion into the techno-economic model. The revised techno-economic model was optimised through pressure variation to give a breakeven syncrude value of $US118 per barrel at Fischer-Tropsch reaction conditions of 10 bar and 240°C. This brings the value well within historical crude price trends.

Submitted in fulfillment of the academic requirements of the degree of Master of Technology, Durban University of Technology, Durban, South Africa, 2016. / The thermophysical properties of the binary mixtures containing biofuel components derived from biomass were determined. Experimental densities, speed of sound, and refractive indices for the binary mixtures (methanol or 1-ethyl-3-methylimidazolium acetate [EMIM][OAc] + furfural or furfuryl alcohol ) were measured at T = (298.15, 303.15, 308.15, 313.15 and 318.15) K. From the experimental data, excess molar volume, E m V , isentropic compressibility, s  , molar refractions, R, and deviation in refractive index, Δn, were calculated. The excess molar volumes were found to be negative for all systems studied. The isentropic compressibility were found to be both positive for the whole composition and temperature range and increases slightly with increasing temperature. The deviation in refractive index was positive over the whole composition range. The obtained values of excess molar volumes and changes of refractive index on mixing were satisfactorily correlated by the Redlich–Kister equation. The Lorentz–Lorenz equation was applied to predict the density and calculate the excess molar volume of the binary mixtures. / M

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Thesis (Sc.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1981. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE / Includes bibliographical references. / by Michael Tully Klein. / Sc.D.

In order to meet growing demands for alternatives to fossil fuels, biomass pyrolysis is a method that has been explored in depth as a method to develop new liquid fuels. Fast pyrolysis is a subtype of pyrolysis reaction in which a specimen is heated at rates in excess of 10C/s in an oxygen-free environment, causing the specimen to thermally degrade and release a volatile bio-oil. The goal of this thesis is to design and commission a novel reactor for the continuous isothermal fast pyrolysis of ground biomass. The reactor design utilizes a vibrating plate heated to a set pyrolysis temperature. Analytical and empirically-derived vibratory transport models are presented for ground Pinus taeda (loblolly pine) to assist in setting the desired pyrolysis reaction time. A condenser system was designed to rapidly evacuate and chill the volatiles to prevent tar formation and secondary reactions. Commissioning tests were run at a pair of temperatures and biomass residence times to determine the degree of agreement between the reactor yields and two-component volatile formation data derived from batch fast pyrolysis of Pinus taeda.

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references (leaves 212-220). Available also in a digital version from Dissertation Abstracts.