With crude oil demand rising and supplies being depleted, alternative energy, specifically biofuels, are of intense scientific interest. Current plant crop based biofuels suffer from several problems, most importantly the use of land needed for food. Cyanobacteria offer a solution to this problem as they do not compete with land for food and produce hydrocarbons that can be used as biofuels. Upon examination of metabolic pathways competing with hydrocarbon synthesis, it appeared that cyanobacteria lacked the major fatty acid degradative metabolic pathway β-oxidation, generally thought to be a universally occurring pathway. Lack of this pathway in cyanobacteria was confirmed by employing a range of analytical techniques. Bioinformatic analysis suggested that potential enzymes with β-oxidation activity were involved in other metabolic pathways. A sensitive assay was set up to detect acyl- CoAs, the substrates of β-oxidation, using liquid chromatography triple quadrupole mass spectrometry. None could be detected in cyanobacteria. No enzymatic activity from the rate-limiting acyl-CoA dehydrogenase/oxidase could be detected in cyanobacterial extracts. It was found that radiolabeled fatty acids fed to cyanobacteria were utilised for lipid membranes as opposed to being converted to CO2 by respiration or into other compounds by the TCA cycle. An element of the β-oxidation pathway, E. coli acyl-CoA synthetase was ectopically expressed in a strain of cyanobacteria and implications of the introduction of acyl-CoA synthesis were assessed. Finally, the regulation of the fatty acid biosynthetic pathway was investigated. It was determined that under conditions of excess fatty acid, the transcription of acetyl-CoA carboxylase and enoyl-ACP reductase was repressed and acyl-ACP synthetase involved in fatty acid recycling was induced. These results were discussed in relation to fatty acid oxidation and hydrocarbon biosynthesis in other organisms.

Microalgae synthesize and store large volumes of lipids (potentially over 25% of dry weight) which could provide a renewable source of biodiesel. Traditional extraction techniques often produce poor lipid yields particularly from microalgae with robust cell walls. This project investigated the role of power ultrasound as a cell disruption step in lipid extraction from four microalgal species. Nile Red staining was used to assess the time when ultrasound induced increased membrane permeability in each species and lipids were extracted using an ultrasound assisted Bligh and Dyer extraction method. A 20 kHz probe system (40% amplitude, 0.086 W/cm3) caused increased lipid recovery from dry biomass in all cases; D. salina (no cell wall) from 15 to 22.5% of dry biomass after 1 minute (26% when stressed with 35 g/L NaCl). C. concordia (thin cell wall) from 7.5 to 10.5% of dry biomass after 2 minutes (27% with 25% nitrogen reduction in growth media). N. oculata (thick cell wall) from 6.5 to 10% of dry biomass after 16 minutes (31.5% when stressed with 30 g/L NaCl). The stressed cultures yield could be improved to 35% when ultrasound was combined with S070 beating beads. Chlorella sp. (thick cell wall) from 6.3 to 8.7% of dry biomass, after 16 minutes (44% was achieved when harvested at day 9 instead of 15). A Dual Frequency Reactor (16 and 20 kHz, 0.01 W/cm3) flow system with S070 beads demonstrated that high lipid extraction yields could be achieved on a larger level with N. oculata. After 4:48 minutes sonication 24% lipid recovery was achieved. This system could theoretically increase daily microalgal oil production from 3.96 to 5.76 L per day when compared to conventional techniques, at an extra production cost of only 2.9 p/litre (1.5% increase). D. salina, N. oculata and C. concordia resumed normal growth following sonication at 20 kHz after 1-20 days (8 minutes treatment for D. salina, 60 minutes treatment for N. oculata and 16 minutes treatment for C. concordia). It was found that the supernatant of sonicated D. salina and C. concordia when added to established cultures were able to boost their growth.

Four studies were conducted to evaluate the potential for post-extraction algal residue (PEAR) to be incorporated as a protein source in the grazing sector of the beef cattle industry. In Experiment 1, blends of PEAR and conventional protein supplements (dried distillers’ grains, DDG; cottonseed meal, CSM) were offered to steers consuming Bermudagrass to evaluate palatability of PEAR. Supplement completion, time required for consumption, and amount of supplement consumed were recorded. In Experiment 2, isonitrogenous amounts of PEAR and CSM (100 mg N/kg BW) were supplemented to steers consuming low-quality forage to compare effects on nutrient utilization. Experiment 3 evaluated the optimal inclusion rate of PEAR to steers consuming low-quality forage. Treatments included no supplemental protein, 3 levels of PEAR (50, 100, and 150 mg N/kg BW) and 1 level of CSM (100 mg N/kg BW). In Experiment 4, the effects of upstream operations on the nutritive value of PEAR were quantified. Observations indicate PEAR may be blended with existing protein sources in the beef industry without negatively affecting palatability, but there may be palatability concerns when PEAR is offered alone. Provision of 100 mg N/kg BW of PEAR or CSM stimulated forage intake (P ≤ 0.05) and increased N retention (P = 0.02) relative to unsupplemented animals. Imbalances in mineral intakes (Ca:P ratio of 8:1) were observed when PEAR was supplemented, but not CSM. Total digestible OM intake (TDOMI) responded quadratically (P = 0.01) to increasing provision of PEAR with maximization occurring when PEAR was provided at 100 mg N/kg BW. There was not a difference in TDOMI (P = 0.13) at isonitrogenous levels of PEAR and CSM, indicating forage utilization was stimulated to a similar extent. Excess mineral levels and imbalances in PEAR were largely a result of cultivation, harvesting, and extraction procedures which could be controlled. Thus, there is potential to alter production streams to optimize oil yield and co-product value. Overall, our results indicate PEAR can be incorporated as a protein source in the beef cattle industry, thus increasing economic viability of biofuel production from algal biomass.

This thesis provides a detailed exploration of the way that four large research-council-funded bioenergy projects have engaged with the politics of bioenergy sustainability. Given the contested nature of sustainable development and the nature of the science in question, this thesis takes a discourse analysis approach to critically examine the functioning of these projects in the context of the wider politics surrounding the issue of bioenergy sustainability. Drawing on in depth interviews and a wide-ranging analysis of the literature, this thesis presents a number of findings. While used in strategically ambiguous ways, under the dominant ecologically modernising discourse governing bioenergy, sustainability is primarily constructed as synonymous with least-cost decarbonisation. Policy support for bioenergy is built around a technologically optimistic storyline, underpinned by a number of assumptions, including a linear view of scientific policy making. This dominant discourse around bioenergy has been challenged in two main ways. The first of these has rejected the over emphasis on carbon balances and economics as the primary metrics against which bioenergy sustainability should be measured. Decarbonising our energy supply has become increasingly dislocated from its underlying (disputed) ethical and moral rationales. As such it has seemingly become an end in its own right. The second challenge is more subtle and involves a rejection of the framing of bioenergy sustainability as a scientific and technical problem. Although reproducing a more administrative type discourse, the science initiatives explored in this thesis appear to reinforce much of the dominant discourse. As well as reflecting certain practices associated with the governments focus on scientific policy making, a lack of reflexivity to the strategic aims of energy policy within science also reflects a strong positivism and shared reliance on the perceived linearity of scientific policy making. It is argued that if science is to be liberated to fully respond to the challenges of sustainability, scientists need to be more reflexive as to the (political) role of science in modern environmental controversies, questioning both what their impacts might be and whose interests they are serving.

Les biopiles enzymatiques sont considérés comme des systèmes potentiellement utilisables pour la production d'énergie renouvelable dans des marchés niches. Une biopile est constituée de deux électrodes associées à des enzymes, catalyseurs biologiques, qui permettent la production d'énergie électrique à partir de réactions chimiques d'oxydoréduction. Ce travail présente la réalisation d'une biopile alcool/oxygène, au sein de laquelle l'alcool est oxydé à l'anode par l'alcool déshydrogénase alors que l'oxygène moléculaire est réduit en eau à la cathode par l'enzyme laccase, en présence de médiateurs spécifiques. L'objectif de ce travail a été tout d'abord de développer des bioélectrodes avec des enzymes immobilisées de manière à minimiser la quantité de biocatalyseur et augmenter sa stabilité. Dans un second temps, l'assemblage de biocathodes et de bioanodes a permis de fabriquer des biopiles à alcool macroscopique et microfluidique. Différentes poudres de carbone combinées à des polymères ont été utilisées pour immobiliser les enzymes et les médiateurs par encapsulation selon diverses configurations. Des analyses électrochimiques ont permis de mettre en évidence l'influence importante de certains paramètres comme la nature du carbone et du polymère, le pH et la température sur les performances des bioélectrodes. Une fois assemblées dans les configurations classique ou microfluidique, ces bioélectrodes ont conduit à des systèmes électrochimiques de génération d'énergie délivrant une densité de puissance maximale de 300μW/cm2 à 0,61V pour la biopile macroscopique et de 45μW/cm2 à 0,5V pour le système microfluidique. / Enzymatic biofuel cells (BFC) are systems of great interest for the production of renewable energy in niche markets. A BFC consists of two electrodes associated with enzymes as catalysts allowing energy production from oxydoreduction reactions. This work is devoted to the development of an alcohol/oxygen BFC for which alcohol is oxidized at the anode by alcohol dehydrogenase while molecular oxygen is reduced to water at the cathode by laccase, in the presence of specific mediators. The objective of this work was first to develop bioelectrodes with immobilized enzymes in order to minimize the amount of biocatalyst and increase its stability. In a second step, biocathodes and bioanodes were assembled to make macroscopic and microfluidic alcohol BFCs. Various carbon powders combined to polymers were used to immobilize enzymes and mediators in various configurations by entrapment. Electrochemical analysis have highlighted the significant influence of certain parameters like the nature of polymer and carbon, the pH or the temperature on the bioelectrodes performances. Once assembled in classical or microfluidic configurations, these bioelectrode led to electrochemical energy generation systems delivering a maximum power density of 300μW/cm2 at 0,61V for the macroscopic BFC and 45μW/cm2 at 0,5V for the microfluidic system.

Doctor of Philosophy / Department of Industrial & Manufacturing Systems Engineering / Zhijian Pei and Donghai Wang / Currently, transportation is almost entirely dependent on petroleum-based fuels (e.g. gasoline, diesel fuel, and jet fuel). Increasing demands for sustainable sources of liquid transportation fuels make it imperative to develop alternatives to petroleum-based fuels. Biofuels derived from cellulosic biomass (forest and agricultural residues and dedicated energy crops) have been recognized as promising alternatives to petroleum-based liquid fuels. Cellulosic biofuels not only reduce the nation’s dependence on foreign petroleum but also improve the environment through reduction of greenhouse gas emissions. In order to convert cellulosic biomass into biofuels, cellulosic biomass must go through a size reduction step first, because large size cellulosic biomass (whole stems of herbaceous biomass or chunks of woody biomass) cannot be converted to biofuels efficiently with the current conversion technologies. Native cellulosic biomass has limited accessibility to enzyme due to its structural complexity. Size reduction can reduce particle size and disrupt cellulose crystallinity, rendering the substrate more amenable to enzymatic hydrolysis. The purpose of this research is to provide knowledge of how size reduction alters biomass structural features, and understand the relationships between these biomass structural features and enzymatic hydrolysis sugar yield. This research is also aimed to investigate the impacts of process parameters in biomass size reduction on the conversion of cellulosic biomass to biofuels to help realize cost-effective manufacturing of cellulosic biofuels. This dissertation consists of eleven chapters. Firstly, an introduction of this research is given in Chapter 1. Secondly, Chapters 2 presents a literature review on cellulosic biomass size reduction. Thirdly, a preliminary experimental study is included in Chapter 3. Chapters 4 to 6 present a three-phase study on confounding effects of two important biomass structural features: particle size and biomass crystallinity. Chapters 7 and 8 investigate effects of sieve size used in size reduction of woody and herbaceous biomass, respectively. Chapters 9 and 10 focus on the relationship between particle size and sugar yield. Chapter 11 studies effects of cutting orientation in size reduction of woody biomass. Finally, conclusions and contributions are given in Chapter 12.

Doctor of Philosophy / Department of Industrial & Manufacturing Systems Engineering / Zhijian Pei / Donghai Wang / Both the U.S. and world economies have been depending on petroleum based liquid transportation fuels (such as gasoline, diesel, and jet fuels), which are finite and nonrenewable energy sources. Increasing demands and concerns for the reliable supply of liquid transportation fuels make it important to find alternative sources to petroleum based fuels. One such alternative is cellulosic ethanol. Research, development, and production of cellulosic ethanol have received significant support from both the U.S. government and private investors. However, several technical barriers have hindered large-scale, cost-effective manufacturing of cellulosic ethanol. One such barrier is related to the low density of cellulosic feedstocks, causing high cost in their transportation and storage. Another barrier is the lack of efficient pretreatment procedures, making pretreatment one of the most expensive processing steps and causing efficiency in the subsequent enzymatic hydrolysis to be very low. There is a crucial need to develop more cost-effective processes to manufacture cellulosic ethanol. Ultrasonic vibration-assisted (UV-A) pelleting can increase not only the density of cellulosic feedstocks but also sugar and ethanol yields. It can help realize cost-effective manufacturing of cellulosic ethanol. This PhD research consists of eleven chapters. Firstly, an introduction of this research is given in Chapter 1. Secondly, a literature review on ultrasonic pretreatment for ethanol manufacturing is given in Chapter 2 to show what has been done in this field. Thirdly, a feasibility test on UV-A pelleting of cellulosic biomass is conducted in Chapter 3. Comparisons of the pellet density and sugar yield are also made between pelleting with and without ultrasonic vibration. Next, effects of process variables (such as biomass moisture content, biomass particle size, pelleting pressure, and ultrasonic power) on output variables (such as pellet density, durability, stability, and sugar yield) have been studies in Chapters 4~6. Chapter 7 compares sugar yields between two kinds of materials: pellets processed by UV-A pelleting and biomass not processed by UV-A pelleting under different combinations of three pretreatment variables (temperature, processing time, and solid content). Next, mechanisms through which UV-A pelleting increases sugar and ethanol yields are investigated in Chapters 8 and 9. Then, a predictive model of pellet density is developed for UV-A pelleting in Chapter 10. Finally, conclusions are given in Chapter 11.

Biomass burning is an important source of trace gases such as CO2, CO and NO, which influence regional and global atmospheric chemistry. Biomass is burnt in bush fires as well as in households as an energy source. Even though there have been numerous studies on domestic biofuel use in Africa over the last two decades there is still a lack of consumption data on the continent. Biofuel is used in rural and urban areas in Africa, but this project focuses on rural consumption. This project aims to quantify biofuel use at representative rural sites around southern Africa and to investigate the spatial and temporal variation. Three sites, one in the south, central and northern parts were selected in each of seven countries (Botswana, Namibia, South Africa, Mozambique, Zambia, Zimbabwe and Malawi). Consumption rates for all fuel types were determined by weighing the fuel used throughout the day. The survey was conducted during the months of May 2003 to February 2004. The forms of biofuel used over southern Africa were found to be wood, charcoal and to a lesser extent maize residue. To obtain a consumption estimate for the whole of rural southern Africa consumption values for Swaziland and Lesotho from previously studies were included. The total annual rural fuelwood consumption in southern Africa is estimated to be 54.7 ± 3.5 Tg with an average daily consumption of 2.55 kg person-1 day-1 . South Africa has the highest consumption of wood and Swaziland the least. While fuelwood was used in all countries charcoal was only consumed in the rural areas of South Africa, Zambia and Mozambique. Rural southern Africa is estimated to consume 8.1 ± 0.8 Tg of charcoal per year. Malawi was the only country to consume maize residue at an average rate of 0.51 ± 0.16 kg person-1 day-1, leading to a consumption of 1.8 ± 0.1 Tg yr-1 over the whole region. The total rural biofuel consumption over southern Africa was estimated to be 64.6 ± 3.6 Tg yr-1. Namibia and South Africa had increased consumption rates between August and October, and Zambia shows slightly higher consumptions between May and July. The other countries show little monthly variation with no specific seasonal trends. There was a slight positive relationship (r2 = 0.168; p = 0.065) between consumption rate and altitude, but the data is very scattered due to monthly variation. Slopes are only shown to be significant between January and March. Altitude is therefore not shown to be a significant controlling factor of biofuel consumption in this study.

A degradação enzimática rápida, eficiente e robusta de polissacarídeos derivados de biomassa lignocelulósica é atualmente um grande desafio na produção de biocombustíveis e considerada uma alternativa viável e promissora para se enfrentar a crise energética mundial e diminuir a dependência das fontes fósseis de energia. O bagaço de cana-de-açúcar no Brasil é a principal matéria lignocelulósica sustentável de grande potencial para a produção do etanol de 2ª geração. O principal requisito para a consolidação dessa abordagem é a disponibilidade de enzimas que hidrolisam a celulose, hemicelulose e outros polissacarídeos em açúcares fermentescíveis e em condições adequadas para a utilização industrial. O presente estudo visou à caracterização molecular, estrutural e funcional da endoglucanase GH12 do fungo Aspergillus terreus (AtGH12) por diferentes técnicas. O gene que codifica para essa enzima foi clonado e expressado no fungo filamentoso A. nidulans linhagem A773. A cepa com maior secreção foi selecionada e a sequência da enzima confirmada por espectrometria de massas MALDI TOF MS. Posteriormente, através de estudos funcionais de parametrização enzimática como pH e temperatura ótimos, estabilidade térmica, efeitos supressores e potencializadores de aditivos, a enzima AtGH12 foi caracterizada bioquímica e fisicamente. A espectrometria de massas do substrato hidrolisado pela catálise enzimática foi tomada como uma forma de investigar o padrão de clivagem da hidrólise e estudo do reconhecimento enzima/substrato para a AtGH12. As caracterizações estruturais das enzimas recombinantes obtidas utilizando as técnicas de espalhamento dinâmico de luz, dicroísmo circular, espalhamento de raios X a baixo ângulo e gel nativo serviram para determinação do enovelamento e estado oligomérico em solução da AtGH12. Com o intuito de fornecer subsídios para o desenvolvimento de coquetéis enzimáticos mais eficazes para hidrólise da biomassa lignocelulósica, a atividade da AtGH12 foi avaliada frente ao bagaço de cana-de-açúcar pré-tratados pelos processos hidrotérmicos e organossolve. Posteriormente, o seu grau de sinergismo nesse tipo de substrato foi determinado com o coquetel enzimático comercial Acellerase&reg. / Fast, more efficient and robust enzymatic degradation of lignocellulosic biomassderived polysaccharides is currently a major challenge in the production of biofuels and considered a feasible and promising alternative to confront the global energy crisis and reduce the dependence on fossil energy resources. The sugarcane bagasse in Brazil is the most abundant and sustainable lignocellulosic material for the production of 2nd generation ethanol. The main requirement for the consolidation of this approach is the availability of enzymes that hydrolyze cellulose, hemicelluloses and other polysaccharides into fermentable sugars suitable for industrial use. The present study was aimed at molecular, structural and functional characterization of an endoglucanase from the fungus Aspergillus terreus (AtGH12) using different techniques. The gene encoding this enzyme has been cloned and expressed in the filamentous fungus Aspergillus nidulans strain A773. The strain with increased secretion was selected and the enzyme sequence was confirmed by mass spectroscopy MALDI TOF MS. Later, functional studies such as analysis of optimal pH and temperature, thermal stability, suppression and enhance effects of additives were applied to the AtGH12 characterization. The mass spectrometry of hydrolyzed substrate from the enzyme catalysis was acquired as a way to investigate the cleavage pattern of hydrolysis and the study of the enzyme/substrate interaction. Structural characterization of the recombinant enzymes was obtained using techniques such as dynamic light scattering, circular dichroism as well as small angle X-ray scattering and native gel, aided to determine the folding and oligomeric state of AtGH12 in solution. In order to provide support for the development of more effective enzyme cocktails for hydrolysis of lignocellulosic biomass, the activity of AtGH12 was evaluated using sugarcane bagasse pretreated by hydrothermal and organosolv processes. Subsequently, the degree of synergism in this type of substrate was measured using a commercial enzyme cocktail Acellerase&reg.

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