Globally, transport accounts for a significant part of the total energy utilization and is heavily dominated by fossil fuels. The main challenge is how the greenhouse gas emissions in road transport can be addressed. Moreover, the use of fossil fuels in road transport makes most countries or regions dependent on those with oil and/or gas assets. With that said, the question arises of what can be done to reduce the levels of greenhouse gas emissions and furthermore reduce dependency on oil? One angle is to study what source of energy is used. Biomass is considered to be an important energy contributor in future transport and has been a reliable energy source for a long time. However, it is commonly known that biomass alone cannot sustain the energy needs in the transport sector by far. This work presents an alternative where renewable electricity could play a significant role in road transport within a relatively short time period. Today the amount of electricity used in road transport is negligible but has a potential to contribute substantially. It is suggested that the electricity should be stored, or “packaged” in a chemical manner, as a way of conserving the electrical energy. One way of doing so is to chemically synthesize fuels. It has been investigated how a fossil free transport system could be designed, to reach high levels of self-sufficiency. According to the studies, renewable electricity could have the single most important role in such a system.    Among the synthetic fuels, synthetic methane (also called synthetic biogas) is the main focus of the thesis. Hydrogen is obtained through water electrolysis, driven by electricity (preferable renewable), and reacted with carbon dioxide to produce synthetic methane. The concept of the mentioned process goes under the name Power to Gas. The electricity to fuel efficiency of such a process reaches about 50 %, but if utilizing excess heat produced during the electrolysis and the reaction, the total process efficiency can reach much higher levels. The economics of the process is as important as the technology itself in terms of large scale implementation. The price of electricity and biogas are the most important influences on the economic viability. The minimum “spread” between purchase and selling price can be determined to obtain a general perception of the economic feasibility. In this case biogas must be sold about 2.6 times higher than purchased electricity per kWh. / <p>QC 20130111</p>

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L'objectif de cette thèse est de concevoir, d'évaluer les performances énergétiques et d'étudier le comportement en régime transitoire pendant les opérations de chauffage et de démarrage d'un procédé réversible Power To Gas qui est une solution pour l'intégration des énergies renouvelables dans le mix énergétique. L'évaluation des performances énergétiques montre que 66,7% de l'énergie électrique entrante est stockée sous forme de substitut du gaz naturel et que les pertes concernent principalement les étapes de conversion en particulier la conversion AC/DC, la co-électrolyse et la méthanation. Le déstockage de l'électricité (Gas To Power) est réalisé en inversant le RSOC en mode SOFC alimenté par le gaz de synthèse (H2 et CO) produit dans un tri-reformeur. Ce procédé est autonome énergétiquement et produit de la chaleur inexploitée qui est à l'origine de sa faible efficacité de 40%. Une étude de la réponse en régime transitoire est conduite en développant des modèles dynamiques du co-électrolyseur réversible, des réacteurs et des échangeurs par le biais de deux logiciels: Matlab et Dymola. Les résultats permettent de préciser la pénalité énergétique et de revoir l'architecture du procédé prédéfinie en régime stationnaire. Plusieurs stratégies ont été étudiées afin d'optimiser le temps de démarrage et l'énergie consommée. Il s'est avéré que le RSOC est le composant qui consomme le plus d'énergie (71% de l'énergie totale) et qui nécessite le plus de temps de démarrage (60% du temps total) à cause de la quantité du gaz utilisée pour le chauffage et du temps important qu'il faut respecter afin d'assurer une augmentation en température progressive qui évite la détérioration des cellules. / The objective of this thesis is to design, evaluate the energetic performance and study the transient behavior during heating and startup operations of a reversible process Power To Gas process which is a solution for the integration of renewable electricity in the energy mix. Steady state models are first established in Aspen plus. Assessment of energetic performance shows that 66.7% of the electrical energy is stored as a Synthetic Natural Gas and the losses are caused mainly by the converting steps: the AC/DC, co-electrolysis and methanation conversions. Electricity production (Gas to Power) is performed by reversing the RSOC in SOFC mode fueled by synthesis gas (CO and H2) produced in a tri-reformer. This process is energetically autonomous and produces untapped heat which causes its 40% low efficiency. A study of the transient response during heat-up and start-up operations is conducted through the development of dynamic models of reversible co- electrolyzer, reactors and heat exchangers by using Matlab and Dymola softwares. The results allow to specify the energetic penalty and to review the architecture of predefined process in steady state. Several strategies have been studied to optimize the time and the energy consumption. It turned out that the RSOC is the slowest component (60% of total time) with the most energetic consumption (71% of total energy) because of the amount of gas used in heat-up operation and the significant time that must be respected in order to ensure an increase in temperature that prevents the cells deterioration.

This thesis analyses how a payment system affects the diffusion of renewable electricity in rural Uganda. A case study is used provided by a start-up company named Pamoja Cleantech. This company is about to sell electricity, which is generated by biomass-based gasification, to a low-income community. Several households are already connected to the established mini-grid while the majority is still not served. A chasm has been identified between the users in the rural village. The reason for this gap between adopters is the high connection fee and a lack of transparent communication. Therefore, diffusion theory has been used to analyse the impact of several payment-related solutions that could close this chasm. First of all, a set of critical factors have been identified concerning general electricity adoption in the case. Those are reliability, trust, transparent communication and satisfying the needs of the local people. Additionally, it has been shown that a payment system, tariffs, and investment costs must satisfy specific requirements in order to be effective, efficient, and positively affect the rate of adoption. These are requirements such as dealing with the cultural incompetence of people being able to save money and to overcome their understanding to have electricity as a status symbol. Therefore an existing technology with its infrastructure is proposed to use: mobile banking. Since this technology has already penetrated Uganda, its convenience to use and satisfaction is high. Additionally, it has advantages such as saving time, security, reliability, and not much space for fraud. This thesis is based on a theoretical framework that is empirically tested and will provide a description of this specific situation in Uganda. Also, it proposes several management recommendations for the company in order to convert adduced threats into opportunities and strengthen their current inclusive business model.

This is a master thesis performed on behalf of WSP, aiming to investigate scenarios for future energy balances in bidding zone 3 in Sweden during year 2040, based on different production alternatives and consumption scenarios. This report aims to highlight the challenges of transitioning to a more electrified energy system where a greater proportion of renewable sources, mainly from hydro, wind, solar and bioenergy, are integrated into the energy system. Increasing the share of weather-dependent electricity production, such as solar- and wind power, set higher standard on the ability to maintain system balance and guaranteeing sufficient power when consumption is high. Higher consumption will be caused by increased electrification of different sectors, and urbanization, which will be necessary in order to achieve climate goals. Production from other power sources, import of electricity from other bidding zones, and flexibility will have to be considered when the demand for electricity cannot be met by solely the production that takes place in bidding zone 3. In this study, EXCEL is used to build a model that calculates future energy balances and presents the extent that future imports of electricity and flexibility, that will be needed to supply enough electricity to bidding zone 3 in the year 2040. With four different production alternatives and three consumption scenarios, 12 different cases of future energy balances are presented.

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The feed-in tariff is a flexible, yet effective mechanism in promoting the proliferation of renewable electricity in California. The tariff creates a stable investment environment that protects both the utilities and the renewable electricity generators. Not only does the system foster capacity growth, but also technological advancement to the point where renewable electricity can compete in the market without assistance. From an environmental standpoint, the feed-in tariff contributes significantly towards achieving the emissions reduction goals set forth by AB32 without causing harmful increases to electricity prices. The feed-in tariff model has been used in countries all over the world and in countless variations. The California model is certainly unique, using a dynamic combination of eligibility requirements, pricing mechanisms, and degression rates. Flaws can already be spotted in the system, but it is too early to tell what type of market effects will truly prevail. The key will be to analyze the market effects as they happen and adjust the tariff accordingly. In the meantime, it would be advantageous to pursue more aggressive green marketing campaigns in order to establish meaningful social norms in favor of environmentally responsible goods and practices. These strong social norms will help to ensure quicker and more effective transitions to green products in the future, including the complete transition to renewable electricity over the coming generations.

Although energy transition is considered one of the main challenges of our time, little attention has traditionally been paid to the actors participating in this transition, such as the producers of renewable electricity. Previous energy policy literature and policy- makers have assumed that these producers are incumbent actors of the current energy system, that is to say, large utilities producing both renewable and fossil-fueled electricity. In reality, new types of producers are entering the renewable electricity production market, without much (if any) previous experience in that industry. This Licentiate thesis studies the new entrants of renewable electricity production in order to identify their motives, their responses to policies, and their ways of implementing their projects. This is conducted through the analysis of 37 cases of new entrants in Sweden. A theoretical background, a complete description of the methods, and an overall presentation of the findings are presented in the first part of the thesis, and in the second part of the thesis, four scientific papers studying the new entrants of renewable electricity production from complementary theoretical approaches are presented. Results show that the new entrant group is heterogeneous in several ways. They have different motives, they are affected by different drivers and pressures, and they are faced with different challenges during their entry processes. Despite that, their share of investments represents the majority of those currently being made in renewable electricity production in Sweden. Based on these results, policy implications are drawn and, in particular, the need for policy-makers and energy policy literature to acknowledge the particularities of the new entrants is highlighted.

Increasing amounts of solar power connected to the low-voltage network will adversely affect the performance of the network. The two impacts that will most often set the limit are overvoltage with the customers and overloading the distribution transformer. In this work, alternative methods have been studied for determining when a transformer is overloaded, to allow more solar power to be connected to the low-voltage network, i.e., increasing the hosting capacity for solar power.A limit-based method on the highest temperature inside the transformer (the hotspot temperature) and a method based on the loss-of-life of the transformer insulation due to hotspot temperatures above the design temperature are those alternative methods in this study. These methods are known as "dynamic transformer rating", a technology proposed in the literature but with very little practical experience in distribution networks.Two models were developed and implemented in MATLAB: a thermal model of the transformer calculating the hotspot temperature for a given time series of loading and ambient temperature; and a model for the loss-of-life of the winding insulation for given time series of the hotspot temperature. These models have been applied to existing distribution networks: measured consumption patterns with high time resolution (10-minute time step) for nine different distribution transformers for 1.5 years (network operator); measured ambient temperature (SMHI); and solar-power production calculated from satellite measurements (Renewables Ninja).For these nine distribution transformers, the time series of the hotspot temperature and the loss-of-life over the 1.5 years have been calculated for different values of the solar power installed capacity on the low-voltage side of the distribution transformer. The resulting time series are used to estimate the hosting capacity for solar power of a 200 kVA transformer. Using the existing design methods, the hosting capacity is 200 kW. Once that value is reached, the further connection of solar power should be stopped until a larger transformer is available. According to IEC design methods, the hosting capacity is about 270 kW using a limit to the hotspot temperature. This value somewhat depends on the loading patterns of the transformer before the connection of solar power. Once that value is reached, the further connection should again be stopped. Even for installed capacity exceeding 270 kW, the loss of life of the transformer insulation is still small and acceptable. This allows for further connection of PV without the immediate need to replace the transformer. Even values up to 350 or 400 kW may be acceptable, but a limit based on loss-of-life will require a detailed risk analysis as the pre-solar loading of the transformer is shown to play an important role.This work has shown that dynamic transformer rating allows more solar power to be connected to a distribution network than using classical rating methods without unacceptable risk for transformer loss-of-life.

In order to handle the mismatch between photovoltaic (PV) electricity production and household electricity use, battery storage systems can be utilized. However, the profitability of PV-battery systems in Sweden is poor, and economic incentives for households to invest in such systems are therefore missing. Hence, it is important to improve the profitability to increase the number of PV-battery installations. The aim of this thesis is to investigate the techno-economic potential of a PV-battery system offering ancillary services, more specifically the primary frequency regulation FCR-N. Five cases of residential PV-battery installations are investigated: the first with a PV system only, the second with a PV-battery system to store surplus PV electricity, and the three other cases with PV-battery systems with the ability to regulate the grid through FCR-N to varying degrees. The results show that providing FCR-N with a PV-battery system offers a substantial techno-economic potential for the system owner. By using available battery capacity for FCR-N, the payback time for a PV-battery system can be shortened significantly. With a battery price of EUR 570 per kWh (VAT excluded) and a discount rate of 2%, the payback time for the entire system can decrease from 32 to 9 years if the battery is used for FCR-N regulation. Furthermore, the payback time for a battery storage can be shortened with FCR-N. Calculated with respect to the economic added value of a battery and with a discount rate of 5%, the payback time can decrease from over 100 years to 4 years.