Bränsle är en av det största kostnaden för sjöfart och ny teknik tas fram för att spara bränsle. Men det finns potential att tillverka bränsle på kryssningsfartyg. En av de största utgifterna för att tillverka biogas iland är uppvärmning av substratet, denna kostnad kan elimineras på fartyg genom att använda spillvärme från motorer och ångsystem.   Detta arbete undersöker möjligheten att producera biogas av toalett- och matavfall som dagligen skapas på kryssningsfartyg, vilka komponenter som behövs samt beräkningar av utrymme de skulle ta och hur stor mängd gas som kan tänkas produceras. Rapporten utfördes genom att undersöka hur biogas produceras i land, vilka är de vanligaste teknikerna som används idag och om de är teknisk möjliga att ha på kryssningsfartyg. För att räkna ut gaspotential samt volym för tankar och reaktor har data samlat in från fyra kryssningsfartyg, data för toalettavfall har tagit från land. Resultatet av beräkningarna blev att potential att tillverka biogas finns men att mängden gas inte kan motivera kostnaden för att installera en biogasanläggning på ett kryssningsfartyg. / Fuel is one of the biggest costs in shipping today, and new technologies are being developed to save fuel. But there is potential to make fuel today aboard cruise ships. One of the biggest expenses in making biogas on land is the heating of the substrate, this cost can be eliminated on ships by using waste heat from engines and steam systems. This report explores the possibility of producing biogas by using toilet and food waste that is created daily aboard cruise ships. What components are needed, calculations of the space they would take and how much gas could be produced. The report was conducted by examining how biogas is produced on land, what are the most common technologies used today? And if they are technically possible aboard a cruise ship? To calculate gas potential, tank and reactor volume. Data has been collected from four cruise ships. The results show that it is possible to create biogas. But that the amount of gas could not justify the cost of building a biogas plant aboard cruise ships.

Tendo em vista o potencial de uso de biomassa obtida do capim-elefante como combustível de fonte renovável em regiões semiáridas, este trabalho teve por objetivo avaliar os efeitos de seis doses de nitrogênio (44, 200, 400, 600, 800 e 1000 kg.ha-1) e de sete lâminas de água (precipitação e irrigação com 0, 40, 54, 100, 135, 148 e 200% da evapotranspiração potencial da cultura - ETc) em sete idades de corte (46, 82, 112, 139, 169, 202 e 231 dias) sobre a produtividade de biomassa seca (BMS, kg.ha-1), altura (m) e índice de área foliar (IAF, m2.m-2) de capim-elefante, cultivar Cameroon. O experimento foi conduzido em Neossolo Quartzarênico localizado em Beberibe (CE), entre maio de 2012 e março de 2013. As doses de nitrogênio constituíram as parcelas e as lâminas de irrigação as subparcelas, segundo o delineamento em blocos casualizados, com quatro repetições. Os tratamentos de irrigação foram dispostos perpendicularmente e os tratamentos de doses de nitrogênio foram dispostos paralelamente à linha lateral de irrigação. Os blocos experimentais foram constituídos por 36 parcelas de 5 x 15 m e o tratamento sem irrigação (L0), com 6 doses de nitrogênio e 4 repetições, foi implantado em local separado para evitar influência da área irrigada. Como fonte de nitrogênio, utilizou-se o sulfato de amônio aplicado a lanço, parcelado em três aplicações. O manejo e a definição do momento de irrigação foi realizado por meio da determinação da capacidade de armazenamento de água no solo e do cálculo da ETc pelo método de Penman-Monteith-FAO. Em relação à BMS, o capim-elefante respondeu ao aumento da adubação nitrogenada e das lâminas de água nas 7 idades de corte avaliadas. O maior acúmulo de BMS ocorreu no tratamento combinado entre 135% ETc e 400 kg.ha-1 de N, aos 231 dias, com 239,85 kg.ha-1.dia-1. A produção de capim-elefante respondeu às lâminas de irrigação em todas as idades de corte analisadas e a maior resposta, em acúmulo diário de BMS de capim-elefante, obtida no tratamento 100% ETc aos 82 dias com 43,46 kg.ha-1.mm-1. As produtividades obtidas nos tratamentos 135, 148 e 200% ETc, a partir dos 82 até 231 dias de idades de corte, foram as maiores e não diferiram significativamente. A produção de BMS de capim-elefante não respondeu ao aumento da adubação nitrogenada isoladamente em seis idades de corte (a partir de 82 até 231) e houve resposta ao aumento da adubação nitrogenada isoladamente aos 46 dias de idade entre as doses 44 e 1000 kg.ha-1 de N, com 3780 e 5005 kg.ha-1 de BMS, respectivamente. A maior resposta, em acúmulo de BMS de capim-elefante, ocorreu no tratamento de 800 kg.ha-1 de N aos 231 dias com 15,383 kg.ha-1.kg-1 de N. O IAF e a altura do capim-elefante responderam às lâminas de água e não responderam à adubação nitrogenada. O IAF e a altura podem ser utilizados como parâmetro na estimativa de produção de BMS de capim elefante até 112 e 202 dias após o corte, respectivamente. Não houve correlação entre o IAF e altura do capim-elefante. / Due to the potential use of elephant-grass biomass as a source of renewable fuel in semi-arid regions, this study aimed to evaluate the effects of six nitrogen rates (44, 200, 400, 600, 800 and 1000 kg.ha-1) and seven irrigation levels (0, 40, 54, 100, 135, 148 and 200% of crop evapotranspiration - ETc) in seven cropping ages (46, 82, 112, 139, 169, 202 and 231 days) on elephant-grass, Cameroon cultivar, dry biomass yield (BMS, kg.ha-1), height (m) and leaf area index (LAI, m2.m-2). The trial was conducted in a Quartzipsamment soil located in Beberibe, Ceará State, Brazil, semiarid region, from May 2012 to March 2013. The nitrogen rates were the main plots and the irrigation levels comprised the subplots, according to a randomized block design with four replications. Irrigation treatments perpendicularly arranged (line source system sprynkler) and nitrogen rates were arranged in parallel to the lateral irrigation line. The experimental block consisted of 36 plots with 5 x 15 m and the treatment without irrigation (L0), with 6 nitrogen rates and 4 replications, was carried out in separate location to avoid infuence of the irrigated area. The nitrogen source was ammonium sulphate, was topdressed onto soil surface, in three split applications during the trial. The irrigation timing and management definition was performed by soil water storage capacity determination and through the Penman-Monteith-FAO crop evapotranspiration calculation. Regarding to BMS production, elephant-grass responded to nitrogen fertilization and irrigation in 7 evaluated periods, and the highest BMS (kg.ha-1.day-1) accumulation response was obtained in the combined treatment 135% ETc and 400 kg.ha-1 N at after 231 days with 239.85 kg.ha-1.day-1. Regarding to irrigation depths treatments, the elephant-grass production increased in all analyzed periods, and the largest BMS (kg.ha-1.day-1) accumulation response was found in treatment 100% ETc after 82 days with 43.46 kg.ha-1.mm-1 applied. The yield in treatments 125, 148 and 200% ETc in cutting ages from 82 to 231 days were the highest and did not differ significantly. The elephant-grass did not respond to nitrogen rates after 6 periods evaluated (82 to 231 days) however the N fertilization responded at the age of 46 days with 3.780 e 5005 kg.ha-1 de BMS between treatments of 44 e 1000 kg.ha-1 de N, respectively and the most intense BMS accumulation response was observed in treatment 800 kg.ha-1 of N at 231 days with 15,4 kg.ha-1.kg-1 N applied. The LAI and height of elephant-grass responded to water depths and did not respond to nitrogen fertilization. Both can be adopted as an elephant grass BMS yield estimation parameter from the age of 112 to 202 days after cutting, respectively. However, BMS versus LAI and LAI versus height interaction showed no correlation between the data collection periods, thus those variables should not be adopted for yield estimation purpose for this crop.

Processos fisiológicos que modulam a aclimatação fotossintética e o crescimento de plantas ao aumento da concentração de CO2 atmosférico são desconhecidos para a maioria das espécies da região amazônica. Neste sentido, este estudo buscou compreender o comportamento fotossintético e a alocação de carbono em Senna reticulata. Esta espécie ocorre em regiões amazônicas que passam por períodos de seca e alagamento e como estratégia de estabelecimento possui crescimento rápido e alta capacidade fotossintética. O objetivo deste estudo foi comparar os parâmetros de trocas gasosas e de crescimento de plantas cultivadas em câmaras de topo aberto sob diferentes concentrações de CO2 (380ppm-ambiente e 760ppm-elevado). Foram realizadas 6 coletas a cada 15 dias, nas quais foram mensurados pontos relativos as curvas AxPAR e AxCi, calculando-se os parâmetros fotossintéticos de cada curva. Os parâmetros de crescimento foram medidos em coletas destrutivas (biomassa) e não destrutivas (área foliar, altura e nº de folhas). As plantas do tratamento elevado apresentaram maior assimilação fotossintética aos 30 e 45 dias de experimento. Após este período foi observada uma mudança no padrão de alocação (de folha para raízes) e as plantas do elevado apresentaram aclimatação na fotossíntese. A aclimatação foi caracterizada primeiramente por uma redução na velocidade de carboxilação da Rubisco, que foi concomitante com a redução na concentração de N e C foliar. A partir disso ocorreu aumento na senescência das folhas, redução na área foliar e redução na concentração de clorofilas. Somente aos 90 dias é que houve um aumento de 30% na biomassa total das plantas submetidas ao tratamento elevado, resultante do aumento de massa principalmente das raízes e folhas. A transpiração e a respiração das plantas do elevado tenderam a ser menores ao longo de todo o tempo, sendo esta diferença significativa apenas aos 75 dias. Apesar das folhas possuírem menor área foliar e número de folhas, foi observado pela análise de massa especifica das folhas que as plantas do tratamento elevado possuem maior massa em relação às do ambiente, possivelmente pelo maior acúmulo de amido. A eficiência no uso da água foi maior nas plantas do elevado aos 30, 75 e 90 dias. A partir desses dados é possível concluir que S. reticulata submetida ao dobro da concentração atual de CO2, desenvolve processos de aclimatação fotossintética sob longa exposição ao elevado CO2, porém consegue produzir mais biomassa. / Physiological processes that modulate growth and photosynthetic acclimation of plants to increased atmospheric CO2 concentration are unknown for most species in the Amazon region. This study aimed to understand the photosynthesis and carbon allocation in Senna reticulata. This species occurs in the Amazonian regions that experience periods of drought and flooding and it has a fast growth and a high photosynthetic capacity as a strategy for its establishment. S. reticulata plants were grown in open top chambers under different concentrations of CO2 (380ppm Ambient - 760ppm Elevated) and their gas exchange and growth were compared. The harvests were performed at 15, 30, 45, 60, 75 and 90 days of experiment. At each date, AxPAR and AxCi curves were carried out to calculate the photosynthetic parameters. Growth parameters included biomass, leaf area, height and number of leaves. The plants of elevated CO2 presented higher photosynthetic assimilation at 30 and 45 days of experiment. After this period was observed a change in the carbon allocation (e.g. root to leaf) and the plants at elevated CO2 demonstrated a photosynthetic acclimation. This acclimation was characterized primarily by a reduction in velocity of carboxylation of Rubisco, which was concomitant with the reduction in N and C concentration in leaves. Also, the plants at elevated CO2 showed an increase in leaf senescence and a reduction in leaf area and chlorophyll concentration. After 90 days there was an increase (i.e. 30%) in total biomass of plants growing under elevated CO2, due to increase of roots and leaves biomass. The transpiration and respiration rates of plants at elevated CO2 tended to be lower throughout the experiment and the significant difference was found at 75 days. Although the leaves have less leaf area and leaf number, it was observed that specific leaf area from elevated CO2 treatment showed higher biomass when compared to ambient CO2. That difference possibly occurred due to greater starch accumulation. The water use efficiency was greater in plants from the elevated CO2 at 30, 75 and 90 days. From these data we conclude that S. reticulata grown at the elevated CO2 produces more biomass despite occurs the photosynthetic acclimation under long exposure to high CO2.

Anaerobic digestion (AD) is a biotechnology that employs natural microbial metabolism under oxygen-free conditions to stabilize organic waste. AD has been shown to be the most environmentally sustainable technology for treating the organic fraction of municipal solid waste (OFMSW), as it allows for the recovery of energy and nutrients from the waste. AD of OFMSW also saves landfill space and reduces leachate generation and fugitive methane emissions from landfills. High-solids AD (HS-AD) technologies (those designed to process feedstocks with >15% total solids content) have been shown to yield additional benefits when compared with liquid AD (L-AD) for treating OFMSW, including reduced parasitic energy demands, reactor volume requirements, water usage, and excess leachate generation. These factors paired with increasingly stringent environmentally-driven legislation have resulted in the steady development of HS-AD technologies in Europe since the 1990’s and the recent advancement of HS-AD in the United States. However, HS-AD implementation in the US is hindered by the low cost of landfilling and a general lack of regulatory drivers encouraging organics separation and recycling. The goal of this research was to contribute to accelerating the implementation and improving the efficiency of HS-AD technologies. The specific objectives were to: (i) assess the state of the art of HS-AD in Europe and the US and investigate trends in development; (ii) conduct a case study assessment of the outlook for implementation of HS-AD in the state of Florida; and (iii) investigate the potential to enhance methane (CH4) yields in HS-AD of lignocellulosic wastes through bioaugmentation with pulp and paper mill anaerobic sludge. Information sources for the assessment of the state of HS-AD in Europe and the US included “grey” and published literature and discussions with consultants and technology vendors. In Europe as of 2014 there were 244 full-scale AD facilities for processing OFMSW with a total capacity of almost 8 million tons per year (TPY), approximately 89% of capacity was “stand-alone” (systems treating only OFMSW), 62% was HS-AD, and 70% installed since 2009 was HS-AD. In the US, as many as 181 AD facilities are now processing OFMSW with an approximate total capacity of 780,000 TPY. Only 24% of the total capacity is currently stand-alone HS-AD with the remaining capacity being stand-alone L-AD (28%) or L-AD codigestion (48%) at wastewater treatment plants or on-farm systems. Development trends in the US are mirroring those in the EU, however, with stand-alone capacity steadily increasing and HS-AD capacity increasing particularly rapidly relative to L-AD for OFMSW processing. The number of full-scale HS-AD facilities in the US has increased from one in 2011 to eight in 2015 and another 19 systems are expected to be operational by 2017. There are at least nine vendors of HS-AD technologies in the US, including four with facilities currently in operation and another four with projects in the planning, permitting, or construction phases. Landfill bans and taxation, mandated source-separation of OFMSW, and policies incentivizing recycling and renewable energy generation are critical factors driving the development and implementation of HS-AD. The case study of HS-AD implementation in Florida incorporated information from industry and data from the Florida Department of Environmental Protection. There is high demand for organics recycling in Florida, with numerous counties generating several hundred thousand TPY of OFMSW and lacking organics recycling infrastructure. HS-AD implementation could increase the statewide recycling rate by as much as 13% and contribute significantly to the reaching the state’s recycling goal of 75% by 2020. Furthermore, up to 7,000 and 3,500 TPY of bioavailable nitrogen and phosphorus, respectively, and up to 500 MW of energy could be recovered through HS-AD of OFMSW in the state. Based on current energy conversion efficiencies, 500 MW of energy translates to either 175 MW of electricity (approximately 660,000 metric tons of CO2 equivalents offsets per year) and 200 MW of heat or nearly 80 million diesel gallon equivalents of vehicle fuel. However, because of the low cost of both landfilling and energy in the state and the lack of markets for compost and renewable energy certificates, legislative action is needed to improve the economic feasibility of HS-AD. Accordingly, a number of policy recommendations were formulated, including banning disposal of OFMSW to landfills and mandating source-separation of OFMSW by all generation sources. Two phases of side-by-side bench-scale batch HS-AD experiments were carried out to investigate the potential to enhance CH4 yield from lignocellulosic waste in HS-AD through bioaugmentation with pulp and paper mill anaerobic sludge. In the first phase, the average CH4 yield from yard waste inoculated with pulp and paper sludge reached 100.2 ± 2.4 L CH4/kg VS, a 73% enhancement compared with the average CH4 yield achieved through inoculation with domestic wastewater anaerobic sludge (58.1 ± 1.2 L CH4/kg VS). In the second phase, CH4 yield from yard waste inoculated with digestate from digesters originally inoculated with pulp and paper sludge was 68% greater than the CH4 yield achieved through inoculation of yard waste with digestate from digesters originally inoculated with domestic wastewater sludge (36.5 ± 0.2 L CH4/kg VS versus 21.7 ± 0.4 L CH4/kg VS). The enhancement in CH4 yield achieved in this study is comparable to enhancements achieved through lignocellulosic pretreatment methods. However, this strategy incurs significantly less additional environmental and economic costs when compared with pretreatment, suggesting that it could serve as an alternative to pretreatment and improve the overall sustainability of HS-AD processes.

Short Rotation Forestry (SRF) for bioenergy could be used to meet biomass requirements and contribute to achieving renewable energy targets. As an important source of biomass it is important to gain an understanding of the implications of large-scale application of SRF on the soil-atmosphere greenhouse gas (GHG) exchange. This study examined the effects of land use change (LUC) from grassland to SRF on soil fluxes of methane (CH4), nitrous oxide (N2O) and carbon dioxide (CO2), and the important drivers in action. Examining soils from a range of sites across the UK, CO2 emission potentials were reduced under SRF with differences between coniferous and broadleaved transitions; these changes were found to be related to changes in soil pH and microbial biomass. However, there were limited effects of SRF tree species type on CH4 and N2O fluxes. A detailed study at an experimental SRF site over 16 months demonstrated a reduction in CH4 and net CO2 emissions from soils under SRF and revealed intriguing temporal dynamics of N2O under Sitka spruce and common alder. A significant proportion of the variation in soil N2O fluxes was attributed to differences between tree species, water table depth, spatial effects, and their interactions. The effects of microtopography (ridges, troughs, flats), and its interactions with water table depth on soil GHG fluxes under different tree species was tested using mesocosm cores collected in the field. Microtopography did not significantly affect soil GHG fluxes but trends suggested that considering this spatial factor in sampling regimes could be important. N2O fluxes from Sitka spruce soils did not respond to water table depth manipulation in the laboratory suggesting that they may also be determined by tree-driven nitrogen (N) availability, with other research showing N deposition to be higher in coniferous plantations. An N addition experiment lead to increased N2O emissions with greatest relative response in the Sitka spruce soils. Overall, LUC from rough grassland to SRF resulted in a reduction in soil CH4 emissions, increased N2O emissions and a reduction or no change in net CO2 emissions. These changes in emissions were influenced both directly and indirectly by tree species type with Sitka spruce having the greatest effect on N2O in particular, thus highlighting the importance of considering soil N2O emissions in any life cycle analysis or GHG budgets of LUC to SRF for bioenergy. This research can help inform decisions around SRF tree species selection in future large-scale bioenergy planting.

In an attempt to meet its ambitious climate change targets, the UK government has decided to incentivise the uptake of bioenergy. However, the full economic costs and environmental impacts of this decision have not yet been quantified at a national level. This is the topic of this research which evaluates the life cycle environmental and economic sustainability of different options for electricity and heat generation using biomass available in the UK, notably waste wood, agricultural residues and wastes, straw, municipal solid waste (MSW), food waste, and energy crops. These results are then used to evaluate the environmental impacts and costs for the whole bioenergy sector in the UK.The results suggest that the environmentally and economically most sustainable electricity generating options are, in descending order: manure/agricultural residue anaerobic digestion (AD) combined heat and power (CHP), Miscanthus co-firing with coal, and chicken litter gasification CHP. The most sustainable heat-generating systems are manure/agricultural residue ADC CHP, waste wood gasification CHP, and chicken litter gasification CHP. However, the use of these technologies is limited by the availability of their respective feedstocks. The research finds that there is currently 30.4 million odt of biomass produced annually in the UK which could be used for electricity and heat generation and that potentially 77.8 million odt could be produced if greater amounts of energy crops are grown. Dry biomass makes up the largest proportion of available biomass, which itself largely consists of wood wastes and energy crops. Dry biomass can therefore make the largest contribution of electricity or heat to potential bioenergy sectors. The electricity-generating biotechnologies identified as those which would make the most sustainable use of wood wastes and energy crops are biomass power plants and co-firing plants. Heat would be most sustainably generated from these feedstocks using biomass gasification CHPs and biomass boilers. According to the results, it is more sustainable to use the UK’s current and potential biomass resources for generating electricity, rather than for producing heat. Electricity from biomass has higher potential for reducing the majority of environmental impacts compared to the current UK electricity grid. Despite this, some impacts are expected to increase, including eutrophication, terrestrial ecotoxicity, depletion of elements and acidification. Furthermore, the economic sustainability of most biomass options is often dependent on subsidies being available, mainly because of the high capital costs. It is recommended that the government look beyond climate change and consider full life cycle impacts when deciding which technologies to incentivise to avoid solving the one problem at the expense of others. It is also advised that subsidies be tied to the sustainability of the feedstock, incentivising the use of waste over energy crops (at least in the short term) and encouraging the displacement of coal and oil. Furthermore, the government should consider scaling the FIT and RHI subsidies smoothly with capacity and consider scaling ROC payments which are currently not linked to capacity at all. Improvements to the environmental sustainability of bioenergy could be gained by funding research into cleaning emissions from biomass combustion, enforcing strict regulation of ash disposal and digestate treatment, and encouraging the reuse and recycling of rare elements.

Klimatförändringarna har medfört en ökad efterfrågan på biobaserade bränslen. Mikroalger har flera intressanta egenskaper som gör dem till en attraktiv och lovande bioråvara för bränsleproduktion. Algerna har en effektiv fotosyntes vilket bidrar till ett lägre landanspråk jämfört med terrestra energigrödor. Dessutom kan odlingarna placeras på oproduktiv mark vilket gör att produktionen inte konkurrerar med andra areella näringar. Genom att integrera algodlingar med industriell infrastruktur kan restflöden som spillvärme, koldioxid, närsalter och vatten från industri nyttiggöras och därmed bidra till en mer effektiv och hållbar biomassaproduktion. I detta arbete studeras en industriell symbios mellan en algodling, det lokala kraftvärmeverket (Hedenverket) och rötningsanläggningen vid Sjöstadsverket i Karlstads kommun. Symbiosen bygger på att rökgaser från Hedenverket används som kolkälla för algerna, spillvärme används för att upprätthålla en lämplig odlingstemperatur i bassängen, varma rökgaser används för att torka biomassan inför förbränning och algernas näringsbehov tillgodoses genom att cirkulera kväve- och fosforrikt rejektvatten från rötningsanläggningen på Sjöstad. Biomassan som produceras används sedan som bränsle i kraftvärmeverket. På så vis skapas nya kretslopp och ett lokalt biobränsle produceras samtidigt som spillflöden från industrin tas till vara. Två tänkbara scenarion för energiutvinning studerades; rötning (Scenario A) och direkt förbränning (Scenario B). För att belysa fördelarna med symbiosen analyserades även ett referensscenario, vilket bygger på att odlingen sker fristående i en så kallad Stand alone-anläggning. Målet med studien var att konstruera en beräkningsmodell för att simulera biomassaproduktionen utifrån platsspecifika förutsättningar samt utvärdera systemet ur miljö-, energi- och kostnadssynpunkt. Studien utformades som en förstudie med syfte att vara ett övergripande men ändå tydligt kunskaps- och beslutsunderlag för berörda aktörer. Arbetet ska belysa symbiosens styrkor, svagheter, möjligheter och risker. Resultatet från studien visar att det genom industriell symbios går att odla alger över en lång säsong vid Hedenverket i Karlstad med det system som föreslås. Den industriella symbiosen förlänger odlingssäsongen med 75 % jämfört med en Stand alone-anläggning och den årliga produktiviteten ökar från 14 till 18 g m-2 d-1. Miljöanalysen visar att det utifrån de systemförslag som undersöks finns liten eller ingen miljönytta med den industriella symbiosen. Scenario A bidrar till att öka CO2-emsisionerna med 0,2 kg m-2 år-1 medan Scenario B bidrar till en reduktion motsvarande 0,2 kg m-2 år-1. En bidragande faktor till detta resultat är att Karlstad Energis el- och värmeproduktion idag i stort sett redan är fossilfri. Detta medför att det algbaserade bränslet ersätter en redan biobaserad process. En högre miljönytta kan åstadkommas genom att överväga alternativa energiutvinningsprocesser. För att tydliggöra miljöfördelarna med en integrerad algodling bör en fullskalig livscykelbedömning för systemet genomföras. Nettoenergi-ration (NER-värde) för Scenario A och Scenario B beräknades till 2,6 respektive 5,3. De höga NER-värdena pekar på att utvinningen av energi med god marginal överträffar energibehovet i produktionsledet för båda processvägarna. Lönsamhetsbedömningen visade att båda scenariona innebär en återbetalningstid som överstiger den tekniska livslängden för anläggningen, 44 och 56 år för respektive scenario. Sammanfattningsvis visar studien att det finns goda möjligheter för att odla alger och framställa ett lokalproducerat biobränsle vid Hedenverket. Trots att det föreslagna systemet med industriell symbios uppvisar positiva resultat beträffande energiprestanda så finns det inte ekonomiska eller miljömässiga förutsättningar för en algodling vid Hedenverket baserat på den systemutformning som föreslagits. Genom att framställa produkter med högre värde från biomassan kan dock ekonomisk- och miljömässiga vinster uppnås, vilket är något som bör utredas vidare.

About forty percent of the world´s population, mostly inhabitants of countries with developing economies, rely on the traditional usage of biomass for energy purposes. The major negative consequences are environmental and health effects. Additionally, the most remarkable social consequence is rural poverty which is directly linked to lack of access to electricity. This places the questions related to biomass utilization for energy production at the core of global welfare.The present work was performed as a part of a larger research project funded by Formas and which involves Swedish and Kenyan partners. The aim of this study was to gather basic knowledge about the characteristics of relevant biomass from sub-Saharan Africa, more specifically from Kenya. Eight different types of biomass, including agroforestry trees, agricultural residues and water hyacinth, were evaluated according to fuel characteristics and thermochemical properties. Ultimate and proximate analyses of the collected biomass were carried out, in addition to heating values analyses. Moreover, the biomass was pelletized and a thermogravimetric analysis was performed in a single pellet reactor. Finally, the composition of the residual ashes was determined. The results show that there was a large variation in the fuel characteristics and thermochemical behaviour of the studied agricultural residues and water hyacinth biomass types, whereas agroforestry trees had rather similar properties and thermochemical behaviour when combusted at the same temperature. In addition, results from the ash composition analyses showed large differences among the studied biomass types, which can be used to better predict and solve problems related to the combustion of these biomass types.

L’océan domine la surface de notre planète et joue un rôle majeur dans la régulation de notre biosphère. Par exemple, les microorganismes photosynthétiques vivant dans l’océan produisent 50% de l’oxygène que nous respirons tous les ans, et une grande partie de notre alimentation et des ressources minérales en proviennent. En cette époque de crise écologique liée à l’accumulation anthropogénique de gaz à effet de serre dans l’atmosphère, il est impératif de développer des énergies plus durables que les carburants fossiles. Le biodiesel pourrait être une source de carburant viable et durable pour remplacer le pétrodiesel mais jusque-là, nos efforts visant à produire des lipides à base de microalgues se sont essentiellement concentrés sur des algues vertes. Dans cette thèse je propose des méthodes pour mieux caractériser une autre catégorie de microalgue : les diatomées. Les diatomées sont une composante importante du phytoplancton et contribuent 40% de la production marine de biomasse primaire. Les diatomées accumulent des lipides en réponse à la carence en nutriments, et même si elles semblent accumuler tout autant de lipides que les microalgues vertes, les voies métaboliques menant à l’accumulation de lipides sont encore peu connues.Dans cette thèse je décris notre caractérisation du glycerolipidome de la diatomée modèle Phaeodactylum tricornutum ainsi que notre étude du remodelage de lipides suite à la carence d’azote ou de phosphate. Des accessions de P. tricornutum isolées dans différentes régions de l’océan ont aussi été étudiées afin de comparer leurs réponses au stress nutritif. Nous avons trouvé que la réponse métabolique menant à l’accumulation de lipides en carence d’azote ou de phosphate est différente. En effet, la carence en azote semble déclencher le recyclage des galactoglycerolipides chloroplastiques ainsi qu’une augmentation de la biosynthèse de novo d’acides gras, alors que la carence en phosphate est plus sévère car nous avons observé une accumulation plus significative de triacylglycerols ainsi que la déplétion totale des phospholipides. De plus, nous avons observé des réponses au stress différentes entre les accessions de P. tricornutum, et en particulier concernant leur capacité à accumuler des lipides. Nous proposons l’hypothèse que ces différences sont liées à leur aptitude à recycler du carbone issu de molécules de stockage non lipidiques.Des approches génomiques ont permis de nombreuses avancées pour mieux comprendre le métabolisme des lipides de microalgues mais notre compréhension des voies de biosynthèse de lipides chez les diatomées est encore limitée. Il y a eu diverses tentatives de caractérisation de la réponse au stress de carence par approche transcriptomique mais l’étude de ces données est incomplète du fait de l’annotation insuffisante des gènes encodant les voies métaboliques pertinentes. Ainsi, dans cette thèse je décris nos tentatives d’annotation de gènes impliqués dans le métabolisme des lipides de P. tricornutum ainsi que les approches d’ingénierie génétique visant à mieux caractériser certains de ces gènes. J’ai également utilisé notre nouvelle annotation de gènes impliqués dans le métabolisme des lipides pour effectuer une étude comparative de plusieurs transcriptomes de P. tricornutum en conditions de carence trouvés dans la littérature. J’ai ainsi pu produire une liste de gènes potentiellement impliqués dans l’accumulation de lipides. Enfin, nous avons pu utiliser ces données pour aider l’interprétation de données génomiques et transcriptomiques issues de la diatomée oléagineuse Fistulifera solaris afin de mieux comprendre comment elle accumule des quantités importantes de lipides pour des applications dans le secteur des biotechnologies et des bioénergies. / The ocean dominates the surface of our planet and plays a major role in regulating the biosphere. For example, the microscopic photosynthetic organisms living in the ocean provide 50% of the oxygen we breathe every year, and much of our food and mineral resources are extracted from the ocean. In a time of ecological crisis linked to the accumulation of anthropogenic greenhouse gases in the atmosphere, we must investigate more sustainable energies than fossil fuels. Much attention has been given to biodiesel but so far most efforts to efficiently produce triacylglycerols in microalgae have focused on green algae. In this thesis I propose approaches to better understand another type of microalgae that is significantly divergent from green lineages: diatoms. Diatoms are a major phylum of phytoplankton in the ocean and account for 40% of marine primary productivity. While diatoms appear to be at least as effective as green algae for producing lipids, the fatty acid and glycerolipid biosynthetic pathways leading to their production have not yet been well characterized. Therefore, I propose to better characterize these pathways in the model diatom Phaeodactylum tricornutum in order to help unlock the potential of diatoms for lipid-based biotechnological applications.In this thesis, I discuss our attempts to establish a reference for the glycerolipidome of P. tricornutum and of our assessment of the lipid remodeling and accumulation that occurs in response to nitrogen- and phosphorus-starvation. A range of accessions of P. tricornutum isolated from different parts of the ocean were also examined to compare their responses to nutrient deprivation. We found that the metabolic response leading to lipid accumulation in different nutrient-deprived conditions are distinct. Nitrogen-deprivation appears to trigger the recycling of chloroplastic galactoglycerolipids as well as a strong increase in de novo fatty acid synthesis while the response to phosphorus-deprivation was more severe as we observed a higher triacylglycerol pool and the complete depletion of phospholipids. Furthermore, we observed several differences among accessions of P. tricornutum regarding their ability to accumulate triacylglycerol in response to nutrient starvation and propose the hypothesis that these differences are linked to their ability to recycle intracellular carbon from non-lipid storage molecules.Genome-enabled approaches have also allowed significant steps towards elucidating the lipid metabolism of microalgae in the past decade, but our understanding of diatom metabolic pathways is still limited compared to that of other microalgae and higher plants. There have been several attempts to characterize the stress response in P. tricornutum by using transcriptomic approaches but this data is difficult to exploit to its full potential without a better annotation of genes encoding the relevant pathways. Therefore, in this thesis I discuss our attempts to annotate P. tricornutum lipid metabolism genes. Based on this annotation I have attempted to better characterize a selection of genes by genetic engineering and have pursued a comparative study of several published transcriptomes of P. tricornutum in nutrient deprived conditions to produce a list of candidate genes likely to be involved in triacylglycerol accumulation. Finally, we used this data to help interpret genome and transcriptome data of the newly sequenced oleaginous diatom Fistulifera solaris to help understand how it accumulates unusually high amounts of triacylglycerol for applications in the biotechnology and bioenergy industry.

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