Thin film solar cells, such as Cu(In,Ga)Se2, have a large potential for cost reductions, due to their reduced material consumption. However, the lack in commercial success of thin film solar cells can be explained by lower efficiency compared to wafer-based solar cells. In this work, we have investigated the aluminum oxide as a passivation layer to reduce recombination losses in Cu(In,Ga)Se2 solar cells to increase their efficiency. Aluminum oxides have been deposited using spatial atomic layer deposition. Blistering caused by post-deposition annealing of thick enough alumina layer was suggested to make randomly arranged point contacts to provide an electrical conduction path through the device. Techniques such as current-voltage measurement, photoluminescence and external quantum efficiency were performed to measure the effectiveness of aluminum oxide as a passivation layer. Very high photoluminescence intensity was obtained for alumina layer between Cu(In,Ga)Se2/CdS hetero-junction after a heat treatment, which shows a reduction of defects at the absorber/buffer layers of the device.

The vast rice production in some developing Asian countries like Indonesia raises expectation on poverty alleviation and energy diversification through second generation biofuel production from rice residues, specifically rice straw. This work attempts to estimate the potential environmental and socioeconomic benefits of rice straw-to-ethanol project in Indonesia. Literature research and interviews are performed to quantify several environmental and socioeconomic indicators that are considered as the major concerns inimplementing an energy project. Assuming all the technically available rice straw in Bali is used (~244-415 kilotonne/year), ethanol production may yield gasoline replacement, lifecycle GHG savings, GDP contribution, foreign exchange savings, and employment beneficiaries of 55-93 ML/year, 140-240 millionUSD/year, 19-32 kilotonne of CO2-equivalent/year, 100-180 million USD/year, and 2,200-3,700 persons, respectively. Sensitivity analyses are done for some parameters, showing that ethanol yield, total capital cost, feed-in-tariff for electricity, and imported crude oil price are the major factors affecting the viability of rice straw-to-ethanol project in Indonesia. / Harnessing agricultural feedstock and residues for bioethanol production - towards a sustainable biofuel strategy in Indonesia

The way its future power systems are designed will have significant impact on sub-Saharan Africa's (SSA) aspirations to move from low electricity consumption rates to enhance life quality and further increase economic opportunity. At present, Africa is experiencing higher economic growth rates than other continents (including Asia). And so is its need for electric power. However, all too often the options that are chosen are the ones with lowest risk and that require little coordination. In part, this is because region-wide planning, coordination and institutions are in their infancy. “Low risk” power plants typically include oil generators that can be sited close to loads, other fossil fuel power plants, and hydro plants that can easily be connected to the continent’s grid. However, hydropower production has been limited due to changes in weather and climate and socio-economic impacts. Additionally, its potential has also not been reached as large sites are far from adequate grids. A restructuring of the energy system that considers both the potential for increased geographical integration while moving gradually towards more sustainable electricity generation may hold significant promise. This work considers the potential of another renewable technology namely concentrating solar power (CSP) and connecting supply and demand centers via high voltage direct current (HVDC) power lines. Specifically, the focus is on utility-scale solar power generation to supply the needs of growing urban centers of demand. It develops a Geographic Information System-based (GIS) model with a spatial resolution of 30 arc-seconds to calculate the cost evolution of the electricity produced by different technologies of CSP plants and the costs of grid development to selected centers of demand. The results show that major SSA metropolis can benefit from distant CSP economically attractive to compete with inlaid coal-based generation. In 2010, total imports of coal exceeded 1.4 million short tons with consequent economic and environmental costs. Solar towers plants endowed with thermal storage may become a leading technology for smoothing purposes with zero fuel costs. Furthermore, Africa’s vast solar resources are far from urban centers of demand and a transmission system capable to integrate high levels of renewable energy while improving reliability of supply is required. The results of this study point to the importance of SSA centers to rely on a Super Grid approach to take advantage from CSP least-cost potential and to discontinue expensive traditional sources. Overall, solar corridors can integrate with geographically-wide wind and hydro potentials to create clean energy corridors and encourage a transition towards more sustainable energy systems.

The knowledge of the influences climate change can have on a regional scale is still very limited. Generally it is known that the climate, land use, energy and water resources are intertwined. The CLEW strategy focuses on an approach to quantify these interrelations. In South Africa, experiencing a fast development, water resources are vital for a continuous prosperous growth. Through a methodological approach the local impacts of climate change on water supply and demand for the City of Cape Town are analysed. The focus lies on the Theewaterskloof Dam in the Riviersonderend catchment. For this study, the future climate data are generated in MarkSim for different SRES scenarios. Using the Water Evaluation And Planning system simulation software WEAP the catchment of interest is modelled to estimate future variation in water availability. For all scenarios the findings are consistent with prior studies forecasting an increase in the annual mean temperatures and a decrease in the annual precipitation. The reduction in annual precipitation consequently leads to a decreased water availability in the Riviersonderend catchment. Despite of the fact that the water resources are likely to diminish, the fixed annual water demand supplied by the Theewaterskloof reservoir is expected to be covered in the future without limitations.

Most of the problems with providing a continuous and sustainable energy supply for the worldwide society are negative consequences to the environment and its living habitants steaming from uses of conventional technologies. Those consequences should be minimized by developing and improving new technologies as well as by utilization of other type of feedstock than fossil fuels, such as biomass, industrial or municipal solid waste. Nowadays, gasification is the main technology for biomass conversion to energy and a great alternative for the thermal treatment of solid waste. The number of various applications for produced gas shows the flexibility of gasification and that is why allows it to be integrated with other industrial processes, as well as power generation systems.             The main objectives of this thesis were to present behavior of different kind of feedstock undergoing pyrolysis/gasification processes in reactors using highly preheated agents and additionally compare the compositions of produced gases. In this thesis two different systems were presented; the first is lab-scale gasifier for the treatment of biocoal, automotive shredder residue (ASR), refuse derived fuel (RDF), biomass (straw pellets) and plastic waste (polyethylene) and the second one is a large up-draft, fixed bed gasifier used for investigation of biocoal. The thesis was divided into four main parts: beginning with theoretical introduction, subsequently showing outcomes from investigations carried out on lab-scale test unit, large HTAG facility and finishing on short conclusions.

In Tunisia, the National Agency for the Environment is encouraging the creation of a carbon footprint method specifically adapted to the Tunisian context. In cooperation with the French National Agency for the Environment, the adaptation of the French carbon footprint method is realised and has to go along with an adaptation of the emission factors. In this framework, this master thesis aims at presenting the emission factors adaptation process led to adapt the accounting tool. First, a literature review enables to present the main notions useful to understand the precise definition of emission factor. Then, a preliminary study of the main carbon footprint tools is presented so as to identify the main characteristics of a carbon footprint method. A comparison is then done to present the differences which can occur between the previous methods. Finally, for each category of emission factor, the adaptation process is presented showing three different ways to adapt emission factors: a replacing of the data in the calculations, an adaptation based on local studies and a more difficult adaptation requiring to develop a new method.

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Wind power generation does, on the one hand, contribute to a less polluting and more sustainable electric power generation mix. On the other hand, the uncertainty and the variability of the power output do challenge the operation of the power system: hourly variations in wind power generation are hardly predictable in a precise way. To decrease the need for balancing power, it might be beneficial from the overall system-perspective to subject power generating companies to stricter balancing incentives/rules. The way the market is designed has become crucial to exploit the existing flexibility in the power system and to increase the efficiency in its operation: inappropriate market designs can counteract all technical achievements. The work conducted for this thesis is embedded in a project on wind power integration and electricity market design following the aim to develop a simulation tool to analyse the consequences of changes in specific market rules. This thesis analyses wind power variations and forecast errors in the Swedish power system and explores the question whether internal ex-ante self-balancing can efficiently reduce the need for balancing power. Applying internal ex-ante self-balancing, every power generating company re-schedules its own power plants in order to balance its commitments towards other market actors with its newest production forecast. This is done shortly before the hour of delivery. To assess the value of this self-balancing, possible trading and scheduling decisions for power generating companies are modelled based on a hydro-thermal generation portfolio within the framework of the Nordic electricity market design. The model is based on a sequence of mixed-integer linear optimisation problems for the clearing of the different sub-markets. Both the data and the model have an hourly time resolution. In a case study, the model is applied on a simplified test-system. The need of real-time balancing by the transmission system operator, the total variable generation cost of the system, as well as the extent to which the power generating companies re-scheduled their production are then used as indicators to evaluate self-balancing. / <p>QC 20121017</p> / Short-term hydro power planning in power systems with large amounts of wind power / Elektra 36141: Korttidsplanering av vatten-värmekraftsystem vid stora mängder vindkraft: System-perspektivet

As the wind industry is developing, it is asking for more reliable short-term wind forecasts to better manage the wind farms’ operations and electricity production. Developing new wind farms also requires correct assessments of the long-term wind potentials to decide whether to install a wind farm at a specific location. This thesis is studying a new generation of numerical weather forecasting models, named mesoscale models, to see how they could answer those needs. It is held at the company Maïa Eolis which operates several wind farms in France. A mesoscale model, the Weather Research and Forecasting model (WRF), was chosen and used to generate high resolution forecasts based on lower resolution forecasts from NCEP’s Global Forecasting System. The stages for implementation of daily forecasts for the company’s wind farms were: explore and configure the model, automate the runs, develop post-processing tools and forecasts visualization software which was intended to be used by the management team. WRF was also used to downscale wind archives of NCEP’s Final Analysis and determine the possibility to use these in assessing wind potentials. Finally the precision of the model in both cases and for each wind farm was assessed by comparing attained data from the model with real power production.

This study concerns the energy future of the county of Stockholm up until 2050 and describes how the energy consumption can be compared to today with the use of scenario methodology. Within energy future studies the backcasting approach is well known and has been put to use in this study. Due to the characteristics of backcasting the study is self-fulfilling, i.e. the future energy scenarios presented in this study satisfy the targets set up in this study. In the light of what may be the largest challenge of our time – the climate change - the aim of this study is to describe how the energy consumption in a fossil fuel free Stockholm county in the year of 2050 may be. The need to reduce the carbon emission to the atmosphere is extensive and of immediate urgency. One part of reducing carbon emission is to relinquish the fossil energy use which is attained either by reducing the energy consumption or switching to renewable energy use or a combination of both of these measures. The scenarios also describe the energy use per capita as well as carbon emissions per capita (due to energy use) besides being fossil fuel free. The energy use and carbon emission per capita is related to what is known as fair share of environmental space which may indicate if the per capita levels deduced in this study is consistent with a sustainable society. Several measures and their potential (to decrease the energy use or shifting into renewable energy fuels) are presented. The scope of measures reaches for example from energy efficiency to new infrastructure but also to reducing measures that reduce the need for example travels. The measures presented in the study are a reality today or will be in the near future, so the study takes on a non-technology optimistic approach. Several of the measures are combined into two different energy-futures for the year 2050 and their energy use is comparedto a business-as-usual-scenario. The business-as-usual-scenario describes the level of energy use in the County of Stockholm if no active measures are taken to reduce the energy use. The scenarios are presented with two different possible alternatives for the economic and population growth, i.e. alternative BAS (eng; base) and HÖG (eng; high). The study with its (only) two different future scenarios is not exhausting thepossible fossil fuel free futures of Stockholm County. Neither the measures nor the energy-futures have been evaluated from an economic or any other perspective. This means the study leave out whether the measures or the energy futures are feasible from an economic perspective or even desirable. The study also leaves out other perspectives like other environmental effects, health issues,equality, aesthetic etc. The aim of presenting different energy-futures of a fossil fuel free Stockholm county is to encourage, simulate stakeholders, policymakers and community citizens to further take an active interest and to start making the changes needed that leads to a fossil fuel free community. The energy-futures but also a few of the measures shows that the future energy use in Stockholm county in the year 2050 may decrease substantially compared 2003. As a result of this the need for renewable energy fuels (for replacing theuse of fossil energy fuels) is reduced. If Stockholm county may take an 10 % part of the bio energy that the whole of Sweden can produce in the future the fossil fuel free energy-futures presented in this study is secured. The energy-futures also shows that the energy use per capita may reach a sustainable level and also that the carbon emission per capita reaches a level far below the suggested level expressed by the Swedish government of 4,5 ton CO2 per capita. One step in the backcasting approach has been left out in this study, i.e. the path to the presented energy-futures. The reason for this is that it needs further analysis of the energy-futures from several other perspectives. As well as analysis over decision making processes, planning processes and different stakeholders involved. However the presented energy-futures may in some cases indicate what type of measures and decisions that needs to be taken and what kind of investments that are needed. Finally, the future is still yet unknown and the energy-futures presented in this study are in the long-time perspective which further increases the uncertainty ofthe scenarios because of uncertainty in collected data, calculations and assumptions made. On the other hand the aim of the study is not to present the most probable energy future but energy futures that fulfil the target of a fossil fuel free Stockholm county in the year 2050.