Biochar has been heralded as a promising technology for climate change mitigation that can also benefit soils. Biochar is a carbonaceous solid produced by pyrolysis of biomass – the thermal decomposition of plant and plant-derived matter in the absence of oxygen. When added to soils, biochar has the potential to increase crop yields and suppress soil emissions of greenhouse gases, whilst sequestering carbon in a stable form. In addition to biochar, biomass pyrolysis produces liquids and gases that can serve as biofuels. Biochar production systems that generate excess heat or power are particularly environmentally and economically attractive. Rotary kilns are the favoured process reactor in many industries, given their potential to handle a wide range of feedstocks and provide good process control. This thesis investigates the potential to coproduce biochar and excess biofuels by slow pyrolysis in a pilot-scale rotary kiln. The work attempts to progress towards the ultimate aim of scaling up the rotary kiln and optimising its operating conditions to produce biochar of good quality along with an excess of useful biofuels. Experimental work, involving the development and application of new methodologies, was used to gain a better understanding of the process. The data gathered were then used to support preliminary numerical simulation efforts towards the development of a comprehensive process model. Five biomass feedstocks were considered: softwood pellets, miscanthus straw pellets, wheat straw pellets, oilseed rape straw pellets and raw rice husks. The granular flow of biomass feedstocks was observed in a short closed drum faced with acrylic and resting on rollers. All pelletized feedstocks displayed similar angles of repose, validating the use of softwood pellets as a model biomass for these feedstocks. Bed mixing, which can improve product uniformity, was slow under typical operating conditions, requiring 5 min to complete at 4 rpm for softwood pellets. Mixing quickened considerably at higher rotation rates. A digital image analysis method was developed to measure the distribution of solid residence times inside the rotary kiln. The mean residence time of softwood pellets ranged from 19 to 37 min under typical operating conditions, decreasing with increases in kiln rotation rate, but mostly unaffected by feeding rates. These findings show that kiln rotation rates must be selected to balance the residence time of solids inside the kiln with bed mixing levels. Thermogravimetry and differential scanning calorimetry were performed on samples of ground softwood pellets under five different heating profiles to study the kinetics and heat flows of the pyrolysis process. Both exothermic and endothermic regions were identified, with most reactions taking place between 250°C and 500°C. Results suggest that exothermic pyrolysis reactions can be promoted by altering the process heating rate, thereby improving net biofuel yield from the process. The thermogravimetric data collected was used to develop a distributed activation energy model (DAEM) of the kinetics of softwood pellet pyrolysis for integration into a comprehensive model of the process. The applicability of the kinetic model to large-scale processes was confirmed using a simplified process model developed to simulate biomass pyrolysis inside the pilot-scale rotary kiln. Although crude, the simplified process model produced sufficiently accurate estimates of char yield for preliminary design purposes. The simplified model also allowed important process parameters, such as kiln filling degree, solid residence time and heating rate, to be evaluated. A series of pyrolysis experiments was performed on the pilot-scale rotary kiln to evaluate the yields of biochar and biofuels and determine the temperature profile inside the kiln. This work required the design of a suspended thermocouple system that measures temperatures along the kiln, both in the gas phase and inside the solid bed. For most experiments at 550°C, a region of high temperature gas and solids was observed, possibly indicative of exothermic reactions. Biochar yield varied from 18% to 73% over the range of feedstocks and operating conditions tested. A vapour sampling methodology that relies on the use of a tracer gas was developed to determine the yield of pyrolysis liquids and gases. Due to analytical difficulties, it was not possible to obtain accurate mass closure with this method. However, the methodology revealed significant air ingress into the pilot-scale rotary kiln that is responsible for partially combusting biofuels produced by the process, thereby reducing their calorific value. Energy balances on the kiln confirmed that the calorific content of pyrolysis liquids and gases exceeds the energetic demand of the process, yielding between 0.3 and 11 MJ in excess biofuels per kg of biomass feedstock. An attempt was made to develop a multiphase model of the flow of vapours and solids inside the rotary kiln using computational fluid dynamics (CFD), but the continuous modelling approach was found inadequate to simulate the dense bed of biomass inside the kiln. The discrete element method (DEM) was sought as an alternative to model the granular flow of biomass inside the kiln. Extensive parameter calibration was required to reproduce the experimental behaviour of softwood pellets observed in the short closed drum. A model of the pilot-scale rotary kiln was constructed to simulate particle residence times. Further parameter calibration was required to replicate softwood pellet holdup inside the kiln. The calibrated model was able to reproduce the mean residence time of softwood pellets within 10% under different kiln operating conditions. However, simulated residence time distributions could not be established as a result of the long execution times required for this modelling work. Few data are currently available on large-scale continuous biomass pyrolysis processes; the experimental data gathered in this thesis help to fill this gap. Along with the numerical simulation work presented herein, they provide the foundation for the development of a comprehensive model of biomass pyrolysis in rotary kilns. Such a numerical model would prove invaluable in scaling up the process and maximizing its efficiency. Future work should consider the agronomic value and carbon sequestration potential of biochar produced under different operating conditions. In addition, the performance and efficiency of different conversion technologies for generating heat and power from biofuels need to be investigated.

The Earth\'s atmosphere is warming due to a combination of natural effects and anthropic activities, which are directly related to the increment of greenhouse gas (GHG) emissions by burning fossil fuel. Brazil stands out in the world economic scenario as the main producer of ethanol, from sugar cane, considered a source of clean, renewable and economically viable energy. The expansion of this crop into pasture areas, in the Center-South region of Brazil, and the intensification in the production of this biofuel to supply the market have raised concerns about its sustainability. The agricultural is one of the main sectors responsible for the emission of GHG into the atmosphere, therefore, more studies are needed about how land use change (LUC) and production intensification, mainly due to the application of agricultural inputs rich in carbon and nitrogen, can affect GHG emissions. In the Center-South region of Brazil, the main LUC is composed of the succession native vegetation areas to pasture, and in sequence to sugarcane. Therefore, two studies were carried out aiming to determine soil GHG emissions under different land uses in the Center-South region of Brazil (Valparaíso-SP), as well as to characterize the emission factor of the main agricultural inputs in either sugarcane planting or ratoon areas. In the first study, three different land use areas were evaluated, composed of native vegetation, pasture and sugarcane. Among the land uses evaluated in this study, the soil under pasture exhibited the highest emission of carbon equivalents (CO2-eq), which was 41-fold higher than under native vegetation and 5.6-fold higher than under sugarcane. In the second study, two experiments were set up to determine the soil GHG emission fluxes after the application of sources of carbon and nitrogen during sugarcane cultivation. Experiment I: set up in a sugarcane planting area with application of ammonium nitrate, limestone and filter cake, in addition to a control treatment without application of any input. Experiment II: set up in a sugarcane ratoon area with application of vinasse and urea in the first year, and vinasse in the second year. In the first experiment, the soil tillage during the planting process produced a larger increase of soil GHG emissions when compared to the sugarcane ratoon area. Among the inputs applied to the cane plant, filter cake or ammonium nitrate produced the highest GHG emissions from the soil. On the other hand, in the area of sugarcane ratoon, the highest emissions were observed with the application of a combination of organic and mineral fertilizers (vinasse and urea), but with the application of only vinasse, the emission increment was less intense. The emission factors for C-CO2 and N-N2O reported by the IPCC are higher than those observed in this study, in the Center-South region of Brazil. The highest emission factor was observed for ammonium nitrate, with 0.13% for N-N2O in the rainy season. Thus, the expansion of sugarcane planted areas plays an important role in GHG emission. New studies on this contribution to GHG emissions are urgently needed in different regions around the world, in order to define measures to limit emissions and aiming at maintaining the sustainability of this biofuel / O aquecimento da Terra decorrente de atividades antrópicas, está diretamente relacionado ao aumento das emissões de gases de efeito estufa (GEE) por queima de combustíveis fósseis. O Brasil se destaca no cenário econômico mundial como o principal produtor de etanol, de cana-de-açúcar, considerado uma fonte de energia limpa, renovável e economicamente viável. A expansão desta cultura sobre áreas de pastagem, na região Centro-Sul do Brasil, e a intensificação da produção deste biocombustível, necessárias para suprir o mercado têm levantado preocupações sobre a sua sustentabilidade. O setor agrícola é uma das principais fases relacionadas à emissão de GEE na atmosfera, sendo necessário maior entendimento sobre como as mudanças de uso da terra (MUT) e intensificação de produção podem afetar as emissões GEE, principalmente após a aplicação no solo de insumos agrícolas ricos em carbono e nitrogênio. Na região Centro-Sul do Brasil, a principal MUT é composta pela sucessão de áreas de vegetação nativa- pastagem- cana-de-açúcar. Foram realizados dois estudos com o objetivo de determinar as emissões de GEE do solo em diferentes usos da terra em Valparaíso-SP, bem como caracterizar o fator de emissão dos principais insumos agrícolas utilizados em áreas de cana planta e cana soca. No primeiro estudo, foram avaliadas três áreas de uso da terra, compostas por vegetação nativa, pastagem e cana-de-açúcar. Entre os sistemas de usos da terra avaliados neste estudo, a pastagem apresentou a maior emissão de carbono equivalente (CO2-eq), no qual representou cerca de 41 vezes maior do que a vegetação nativa e 5,6 vezes maior do que a cana-de-açúcar. No segundo estudo, dois experimentos foram conduzidos simultaneamente para determinar os fluxos de emissões de gases do solo após a aplicação de fontes de carbono e nitrogênio durante diferentes fases do ciclo da cana-de-açúcar. Experimento I: realizado em uma área de plantio de cana-de-açúcar com aplicação de nitrato de amônio, calcário e torta de filtro, além de um tratamento controle sem aplicação de nenhum insumo. Experimento II: área de cana soca com aplicação de vinhaça e ureia no primeiro ano, e vinhaça no segundo ano. No primeiro experimento o revolvimento do solo no processo de plantio proporcionou as maiores emissões de GEE quando comparada a área de cana soca. Dentre os insumos aplicados na cana planta, a torta de filtro ou nitrato de amônio proporcionaram as maiores emissões de GEE do solo. Por outro lado, na área de cana soca, as maiores emissões foram verificadas quando houve a combinação de fertilizante orgânico e mineral (vinhaça e ureia), sendo que com a aplicação somente de vinhaça, o aumento das emissões foi menos intenso. Os fatores de emissão para C-CO2 e N-N2O relatados pelo IPCC ainda são maiores do que os observados neste estudo, realizado na região Centro-Sul do Brasil, no qual o maior fator de emissão foi observado para nitrato de amônio, com 0,13% para N-N2O, na estação chuvosa. A expansão das áreas plantadas de cana de açúcar tem importante papel na emissão de GEE, sendo necessários novos estudos sobre essa contribuição em distintas regiões de produção em todo o mundo, na busca de medidas menos emissoras, visando a sustentabilidade deste biocombustível

Made available in DSpace on 2017-07-10T15:14:42Z (GMT). No. of bitstreams: 1 Augustinho Borsoi.pdf: 1096663 bytes, checksum: 924a7bc21d838e8f033dbbd628a41ad1 (MD5) Previous issue date: 2012-02-03 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This study aimed to assess the economic feasibility of biodiesel production in an associative form by family farmers from the municipality of Corbélia-PR. Biodiesel has proven to be a socio-economic and environmental alternative for the partial or total substitution of diesel oil due to its similar physicochemical characteristics. In Brazil, the biodiesel has great social appeal by the utilization of raw material that comes from family agriculture. However, the participation of family farmers acting directly in the transformation of vegetal oil into biodiesel still requires studies concerning to its economic feasibility. The present work was developed by means of a simulation, in order to verify the economic feasibility of the installation of a biodiesel plant able to produce 1000 L day-1 by family farmers. The raw material used for the extraction of oil were soy, sunflower, and canola, in the summer and winter crops, once that pies made of these oilseeds can be used to feed cattle. Cash flow, with expenses (output) and revenue (input) before and after the installation of the plant were elaborated. From the cash flow, it was possible to perform the economical analysis, by using the following as indicators: Net present value (NPV), Internal rate of return (IRR) and Payback period. The IRR for the project was 43%, the NPV was R$ 92,049.96 and the payback was 2.57 years. Based on these indicators, one can conclude that the production of biodiesel in association by the family farmers showed economic feasibility. It is also relevant to highlight the importance of interaction among the property s activities, by using pies to feed the cattle. / O estudo teve por objetivo avaliar a viabilidade econômica da produção de biodiesel de forma associativa por agricultores familiares do município de Corbélia-PR. O biodiesel apresenta-se como uma alternativa socioeconômica e ambiental para a substituição parcial ou total do óleo diesel, devido a suas características físico-químicas semelhantes. No Brasil, o biodiesel tem grande apelo social, uma vez que a matéria-prima utilizada para sua produção é oriunda da agricultura familiar. No entanto, a participação de agricultores familiares atuando diretamente na transformação de óleo vegetal em biodiesel ainda requer estudos quanto à sua viabilidade econômica. Este trabalho foi desenvolvido por meio de uma simulação, para verificar se a instalação de uma usina de biodiesel com capacidade para 1000 L dia-1 por agricultores familiares seria viável. Como matérias-primas para a extração de óleo foram utilizadas: soja, girassol e canola, nas safras de verão e inverno, já que a torta dessas oleaginosas pode ser utilizada na alimentação de bovinos de leite. Foram elaborados fluxos de caixa com os custos (saídas) e receitas (entradas) antes e depois da instalação da usina. A partir do fluxo de caixa, foi realizada a análise econômica, na qual foram usados como indicadores o valor presente líquido (VPL), a taxa interna de retorno (TIR) e o período de retorno de capital (payback). A TIR do projeto foi de 43%, o VPL, de R$ 92.049,96 e o payback, de 2,57 anos. Concluiu-se, a partir desses indicadores, que a produção de biodiesel em associação pelos agricultores familiares apresentou viabilidade econômica. Destacou-se, também, a importância da interação entre as atividades da propriedade, por meio do uso da torta para alimentação do gado de leite.

Algae-derived biodiesel is currently under investigation as a suitable alternative to traditional fossil-fuels. Though it possesses many favorable characteristics, algae remains prohibitively expensive to mass produce and distribute. The most economical means of growing algae are large-scale open pond raceways. These, however, suffer from low culture densities; this fact impacts the cost directly through diminished productivity, as well as indirectly by raising costs due to the necessity of dewatering low culture density raceway effluent. Algae, as a photosynthetic organism, achieves higher culture densities when sufficient light is provided. In open ponds this can be accomplished by frequently cycling algae to the raceway surface. The current work examined delta wing vortex generators as a means of instigating this cycling motion. In particular the impact of spacing and angle of attack was analyzed. These vortex generators were found to significantly increase vertical mixing when placed in a series, developing precisely the motion desired. Their impact on power requirements was also examined. Specifically it was shown that increases in spacing and decreases in angle of attack result in lower power consumption. It was demonstrated that the most efficient mixing generation is achieved by larger spacings and smaller angles of attack. The impact that these devices had on raceway turbulence as measured by dissipation rate was also investigated and compared to published values for algae growth. Raceways were found to be significantly more turbulent than standard algae environments, and adding delta wings increased these levels further.

Large scale biofuel production from microalgae is expected to be integrated with point source CO2 sources, such as coal fired power plants. Flue gas (CO2) integration represents a required nutrient source for accelerated growth while concurrently providing an environmental service. Heavy metals inherent in coal will ultimately be introduced into the culture system. The introduced heavy metals have the potential to bind to microalgae cells, impact growth due to toxicity, and negatively impact the quality of biofuel and other microalgal derived products. Heavy metals As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Sb, Se, Sn, V and Zn, commonly present in coal, were introduced to the microalgae growth medium at a concentration expected from a 7 day growth period using coal flue gas. Experimentation was conducted with Nannochloropsis salina cultivated in photobioreactors at a light intensity of 1000 μmol m-2 s-1. Heavy metals negatively impacted the growth with the average productivity being 0.54 ± 0.28 g L-1 d-1, corresponding to a decrease of 52% in biomass yield compared to control growths. Heavy metal analysis showed significant binding of the majority of the heavy metals to the biomass. A lipid content analysis found a decrease in lipid content from 38.8 ± 0.62% to 31.58 ± 0.50% (percent dry biomass). Control and heavy metal contaminated biomass were processed into biofuel through one of two different in-situ transesterification techniques, either acid-catalyzed or supercritical methanol conversion. The acid-catalyzed conversion resulted in an average crude biofuel production decrease from 0.31 ± 0.03 grams biofuel/gram microalgae for the control algae to 0.28 ± 0.02 grams biofuel/gram microalgae for the heavy metal algae, representing a 9.7% reduction. Supercritical methanol conversion exhibited a similar trend corresponding to a 15.8% reduction. Compared to the control, the total production of biofuel from the contaminated system was decreased by 51% for the acid-catalyzed conversion and 55% for the supercritical methanol conversion. Heavy metal analyses were performed on the biofuel, lipid extracted algae, and other biofuel conversion byproducts. Biochemical methane potential testing was performed on the lipid extracted algae to determine the effect of heavy metals on the generation of biogas. The effects of heavy metals in combination with the effects of acid catalyzed transesterification were found to have a positive effect on the amount of methane produced with an average productivity of 105.89 mL g-COD-1 from the heavy metals contaminated LEA compared to the control microalgae biomass which produced 53.25 mL g-COD-1.

Renewed momentum in the microalgae industry due to commercial interest in biofuels and bioproducts is driving the need to increase the economic competitiveness of large-scale microalgal production. Current knowledge of membrane systems common in other disciplines, such as environmental engineering, marine science, and biomedicine, are relevant to algae production. With pore sizes ranging from microns to angstroms, membranes provide tailored functions for solid/liquid separation (cell retention, biomass concentration and dewatering), gas/liquid separation (gas delivery and removal), and solute/liquid separation (bioproduct recovery, feedstock preparation and effluent recycling) that are problematic or not possible with other technologies. Though membranes have great potential to facilitate cultivation and harvesting, challenges in energy reduction and fouling mitigation need to be overcome for long-term, cost-effective applications. This body of research includes a thorough literature review of membrane applications in the algal industry and three experimental studies investigating ways to improve the cultivation and harvesting of microalgal species in wastewater. The first study investigated the growth of native and augmented algal communities in various growth media. Algal monocultures (Chlorella sorokiniana and Botryococcus braunii) and algal communities native to clarifiers of a wastewater treatment plant were batch cultivated in 1) clarified effluent following a BOD removal reactor (PBCE), 2) clarified effluent following a nitrification reactor (PNCE), and 3) a reference medium (RM). After 12 days, all algal species achieved nitrogen removal between 68-82% in PBCE and 37-99% in PNCE, and phosphorus removal between 91-100% in PBCE and 60-100% in PNCE. The pH of the wastewater samples increased above 9.8 after cultivation of each species, which likely aided ammonia volatilization and phosphorous adsorption. Both monocultures grew readily with wastewater as a feedstock, but B. braunii experienced significant crowding from endemic fauna. In most cases, native algal species' nutrient removal efficiency was competitive with augmented algal monocultures, and in some cases achieved a higher biomass yield, demonstrating the potential to utilize native species for nutrient polishing and algal biomass production. In the second study, the isolated cultivation of algal resource utilizing selectivity (ICARUS) process was conceived and developed. ICARUS integrates a passive membrane photobioreactor configuration with wastewater as a growth medium. Eleven membranes of varying porosity and materials were examined based on characteristics and resulting algae productivity. Four ICARUS series (40kDa-PVDF, 0.53 g L-1, 14.1 mg; 0.1µm-PVDF, 0.43 g L-1, 16.6 mg; 12kDa-RC, 0.35 g L-1, 14.5 mg; 0.2 µm-CA, 0.41 g L-1, 14.5 mg) had a final cell density and mass yield that was significantly higher than that of suspended culture (0.25 g L-1, 9.1 mg). Optimal pore size range was identified to be 50-1000 kDa. Six additional series (0.2µm-CA, 0.1µm-PVDF, 40kDa-PVDF, 12kDa-RC, 3.5kDa-PVDF, and 3kDa-RC) also sustained significantly longer exponential growth phases than the suspended cultures. The ICARUS series maintained an average pH of 9.55, which was significantly lower than the average pH of 10.21in the suspended culture. Membrane characteristics affecting the variability in microalgae productivity were evaluated in 2D and generalized linear models. In the third study, select membranes from the laboratory experiments in Chapter 5 (12kDa-RC, 40kDa-PVDF, 7µm-NY) were tested in extended field conditions at a wastewater treatment plant, where the movement of dissolved constituents and biomass productivity were compared to that of closed suspended series. All ICARUS series had higher biomass productivity (RC, 2.87 g L-1; PVDF, 10.6 g L-1; NY, 8.45 g L-1) than the suspended series (0.38 g L-1), which was due to both a longer exponential growth phase and passive dewatering in the ICARUS series. Dissolved ions passed readily across each membrane, and no nutrient limitation was apparent in any series. Gas exchange was slower than expected, which may have been due to external and internal attached growth utilizing gases at the membrane surface. However, dissolved oxygen concentration did not limit algal growth, and adequate carbon dioxide was available to regulate ICARUS pH. In fact, the ICARUS series maintained an average pH of 7.6, whereas the pH of the control series reached 9.8-10.5. The invasion of endemic wastewater species was dependent on pore size; the RC and PVDF series maintained a monoculture, but the NY series had severe contamination. The resulting research has demonstrated a proof-of-concept of a new microalgal cultivation method which may reduce the cost of large-scale cultivation efforts integrated at wastewater treatment plants or within existing algal production facilities. Investigating various wastewater effluents, membranes, and algal strains has allowed for recommendations for the operation of scaled-up systems. Future research should focus on mechanisms and characteristics of biofouling as well as the operation of a field scale prototype. By improving large scale algal cultivation, algal biofuels may become more economically competitive with fossil fuels or other renewables, enhancing their participation in the country's diverse energy portfolio.

<p>Arbetet har bestått i att utföra en informativ webguide över en anläggning i Västerås som tillverkar biogas och biogödsel av matrester. Beställaren heter VafabMiljö. Mina kontaktpersoner, Caroline Eklöv och Åsa Lindén, är skolinformatörer. Guiden ska publiceras på VafabMiljös hemsida för skolklasser på Internet och där fungera som en förlängning av informatörernas arbete i skolorna. Målgruppen är barn i årskurs 3-5. En uttalad förebild fanns: Göteborgsföretaget Gryaabs guide om vattenrening Vart tar bajset vägen? (http://www.gryaab.se/).</p><p> </p><p>Under arbetets gång har design- och funktionsbesluten fattats med stöd av:</p><ul type="square"><li>Intervju med kund och besök på anläggningen</li><li>Omvärldsanalys, mestadels på Internet</li><li>Egna erfarenheter</li><li>Kontinuerliga utprovningar</li><li>Litteratur</li></ul><p> </p><p>Arbetet har utförts i Illustrator och Adobe Flash.</p><p> </p><p>Eftersom det var många delar i processen som skulle illustreras var det nödvändigt att arbeta snabbt. Önskemål från kunden var att låta enkelt, tydligt och roligt gå före korrekt återgivning. Detta har lett till ett manér där jag använt mig mer av symboler än verklighetstrogen avbildning. I rapporten beskrivs intressanta designbeslut där min målsättning varit att låta begriplighet gå före realism.</p>

<p> </p><p>Introduction:<strong> </strong>Significant changes in the global ecosystem, together with a potential shortfall in oil resources, have stimulated intense interest in the development of other sources of energy, and most particularly biofuels since these are basically considered to be less harmful to human health than petroleum-based fuels. However, information about the impact of biofuel-derived vehicle emissions on human health is limited and incomplete<strong>. </strong></p><p> </p><p>Aim of the study:<em><strong> </strong></em>To identify those biofuels that are less detrimental to human health on the basis of published results from toxicological and chemical studies of vehicle emission products.</p><p> </p><p>Tasks of the study: To review systematically all conventional and alternative fuels used in internal combustion engines, to identify all known toxic emission products formed by such fuels, to review their toxic effects on human health, and to analyse the data collected in order to develop conclusions concerning the possible health benefits deriving from the use of alternative fuels.</p><p> </p><p>Materials and methods: In order to fulfil the requirements of a complete, comprehensive and up-to-date review of the toxic effects of automotive exhaust, an extensive search of official scientific data sources has been performed. Relevant publications were retrieved from public domain databases with a toxicological focus such as Toxcenter and CAplus, as well as from the websites of the US<em> </em><em><em>Environmental Protection Agency</em></em><em> </em>and the US <em><em>Agency for Toxic Substances and Disease Registry</em></em><em><strong>.</strong></em><strong> </strong>Keywords<strong> </strong>employed in the literature search were: petrol, gasoline, diesel exhaust, emission, biofuel, biogas, biodiesel, bioethanol, bioalcohol, toxicity, methanol and ethanol. A total of 295 references were initially selected relating to the period 1962 to 2008, and 142 of these presented titles and abstracts that met the main inclusion criteria, i.e. describing toxicological and epidemiological studies in humans. In cases where eligible studies relating to the goals and tasks of the review were limited or not available, some <em>in vitro</em> or <em>in vivo</em> toxicological studies involving animal models were included.</p><p> </p><p>Results:<strong> </strong>In comparison with petroleum diesel, the emissions derived from biodiesel contain less particulate matter, carbon monoxide, total hydrocarbons and other toxic compounds including vapour-phase C1-C12 hydrocarbons, aldehydes and ketones (up to C8), selected semi-volatile and particle-phase polycyclic aromatic hydrocarbons (PAHs). Whilst sulphur-containing compounds appear to be undetectable in biodiesel, nitrogen oxide and a soluble organic fraction comprising unregulated pollutants including the “aggregated toxics” (i.e., formaldehyde, acetaldehyde, acrolein, benzene, 1,3-butadiene, ethylbenzene, <em>n</em>-hexane, naphthalene, styrene, toluene and xylene) are present at elevated levels. Toxicological studies have shown that the mutagenicity of exhaust particles from biodiesel is normally lower than those obtained from petroleum diesel, however, rapeseed oil-derived biodiesel exhibits toxic effects that are 4-fold greater than petroleum diesel. Such enhanced toxicity is probably caused by the presence of carbonyl compounds and unburnt fuel. The toxicity of highly volatile components of biofuel exhaust has not yet been evaluated accurately. A substantial portion of these compounds was apparently lost in the process of preparing the test samples used for the assays (during the evaporation). The overall recoveries of these compounds have not been evaluated and the accuracy of the sample preparation method has not been validated. Hence, it could be that the cytotoxic effect of biodiesel exhaust is higher than that reported. Moreover, compared with fossil diesel, fuel derived from rapeseed oil emits particulate matter with increased mutagenic effects. Epidemiological investigations of the effects of biofuels on humans are very sparse but have revealed dose-dependent respiratory symptoms following exposure to rapeseed oil biodiesel, although the observed differences between this fuel and petroleum diesel are not significant. Such data, however, give rise to serious concerns about the future usage of this plant material as a replacement for established diesel fuels. Combustion of alcohol-based fuels leads to a reduced formation of photochemical smog in comparison with gasoline or diesel, however, the emission of aldehydes (officially classified as carcinogenic or potentially carcinogenic) is several times higher. The toxicity of the exhaust emissions of gasoline-fuelled engines is generally significantly greater than that of alcohol-burning engines. However, some harmful effects from ethanol blends might be expected, such as enhanced emissions of carcinogenic PAHs and increased ozone-related toxicity associated with the high level of aldehydes emitted. The use of ethanol–diesel fuel blends gives rise to increases in regulated exhaust emissions and, possibly, to greater emissions of aldehydes and unburnt hydrocarbons. The most promising fuels, in terms of reduced toxicity and genotoxicity of exhaust emissions, are methanol-containing blends. However, the emission from these fuels still contains formaldehyde, which is a carcinogen. The use of biogas can significantly reduce emissions of total PAHs and formaldehyde and, consequently, the risk of lung toxicity. On the other hand, the emissions of particulate matter by compressed natural gas, and the mutagenic potencies of the exhaust, are similar to those associated with gasoline and diesel fuels<strong>. </strong></p><p> </p><p>Conclusions: The use of biofuel is currently viewed very favourably and there are suggestions that the exhaust emissions from such fuel are less likely to present risks to human health in comparison with gasoline and diesel emissions. However, the expectation of a reduction in health effects based on the chemical composition of biodiesel exhaust is far from reality. Thus, although toxicological evidence relating to the effects of biofuels on humans is sparse, it is already apparent that emissions from the combustion of biofuel and blends thereof with petroleum-based fuels are toxic. In addition to the regulated toxic compounds, such as total hydrocarbons, carbon monoxide, nitrogen oxides, particulate matter and polycyclic aromatic hydrocarbons, biofuel emissions contain significant amounts of various other harmful substances that are not regulated, e.g. carbonyls (including formaldehyde, acetaldehyde, benzene, 3-butadiene, acrolein, etc.). Whilst biofuels may be potentially less damaging to human health than petroleum fuels, considerable harmful effects must still be expected. Substitution of conventional fuel by biofuel decreases the concentration of regulated toxic pollutants in vehicle exhaust, but increases the concentration of some unregulated toxic pollutants emitted from on-road engines. Generally, the toxicity of biofuels decreases in the order biodiesel>biogas>ethanol>=methanol. In this respect, methanol produced by the oxidation of biogas appears to represent an alternative fuel that exhibits the least potential for damage to human health, however, this alcohol represents a source of formaldehyde pollution and is carcinogenic.</p><p>.</p><p> </p>

Today’s biomass-fired combined heat and power (CHP) plants have surplus heat production capacity during warmer times of the year. In order to allow them to increase their electricity production, it is essential to find a use for the surplus heat. Additionally, the transport sector is struggling with high fuel prices and the contribution of CO2 emissions to global warming. A promising way of reducing the negative effects caused by combustion of fossil fuels in the transport sector is to mix ethanol with gasoline, or to use pure ethanol in modified engines. Ethanol is produced by fermentation at low temperatures and the production process could be integrated with CHP plants. The first generation of ethanol production as fuel has recently been criticized for competing with food crops and for its production chain being a larger polluter than was first thought. The second generation of ethanol production from lignocellulosic materials offers very promising results, but this process has several steps that are energy demanding. This thesis presents the findings of research on the configuration of a CHP plant with an integrated second generation ethanol production process. It also presents the operational economics and optimal locations for such plants in Sweden. Two case studies were performed to compare different feedstocks for ethanol production. The results show that when electricity prices are high, CHP plants benefit from heat consumption. Even with low yields in an ethanol production process, the integrated plant can be profitable. The plant must be located where there is sufficient heat demand. A cellulosic ethanol production process can work as a heat sink with profitable outcomes even with the current state of development of cellulosic ethanol technology.

Vegetable oils have been researched as alternative source of energy for many years because they have proven themselves as efficient fuel sources for diesel engines when used in the form of biodiesel, vegetable oil–diesel blends, vegetable oil-water-diesel blends and mixtures thereof. However, very few studies involving the use of emulsified low grade alcohols in straight vegetable oils, as fuels for combustion have been published. Even, the published literature involves the use of emulsified fuels only for compression ignition diesel engines. Through this project, an attempt has been made to suggest the use of alcohol-in-vegetable oil emulsions (AVOE) as an alternate fuel in stationary burners like electric utility boiler producing steam for electricity generation and more dynamic systems like diesel engines. The main goal of this study is to understand the effect of the combustion of different methanol-in-canola oil emulsions, swirl angle and equivalence ratio on the emission levels of NOx, unburned hydrocarbons (UHC), CO and CO2. The 30 kW furnace facility available at Coal and Biomass Energy Laboratory at Texas A & M University was modified using a twin fluid atomizer, a swirler and a new liquid fuel injection system. The swirler blades were positioned at 60° and 51° angles (with respect to vertical axis) in order to achieve swirl numbers of 1.40 and 1.0, respectively. The three different fuels studied were, pure canola oil, 89-9 emulsion [9 percent methanol – in – 89 percent canola oil emulsion with 2 percent surfactant (w/w)] and 85-12.5 emulsion [12.5 percent methanol – in – 85 percent canola oil (w/w) emulsion with 2.5 percent surfactant]. All the combustion experiments were conducted for a constant heat output of 72,750 kJ/hr. One of the major findings of this research work was the influence of fuel type and swirl number on emission levels. Both the emulsions produced lower NOx, unburned (UHC) hydrocarbon and CO emissions than pure canola oil at both swirl numbers and all equivalence ratios. The emulsions also showed higher burned fraction values than pure oil and produced more CO2. Comparing the performance of only the two emulsions, it was seen that the percentage amount of methanol added to the blend had a definite positive impact on the combustion products of the fuel. The higher the percentage of methanol in the emulsions, the lesser the NOx, UHC and CO emissions. Of all the three fuels, 85-12.5 emulsion produced the least emissions. The vorticity imparted to the secondary air by the swirler also affected the emission levels. Increased vorticity at higher swirl number led to proper mixing of air and fuel which minimized emission levels at SN = 1.4. The effect of equivalence ratio on NO_x formation requires a more detailed analysis especially with regards to the mechanism which produces nitrogen oxides during the combustion of the studied fuels.