Dissertations / Theses on the topic 'Alternative renewable energy'

Increased share of Renewable Energy Sources (RES) in the generation mix requires higher flexibility in power system resources. The intermittent nature of the RES calls for higher reserves in power systems to smooth out the unpredictable power fluctuations. Grid-tied energy storage systems are practical solutions to facilitate the massive integration of RES. The deployment of Battery Energy Storage Systems (BESS) on the power grids is experiencing a significant growth in recent years. Thanks to intensive research and development in battery chemistry and power conversion systems, BESS costs are reducing. However, much more advancements in battery manufacturing as well as additional incentives from the market side are still needed to make BESS a more cost-effective solution. Planning and operation of the BESS significantly influence its profitability. It is quite important to find optimal sizes of batteries and inverters. Sizing of the BESS for two different applications is addressed in this work. In the first application, the BESS is co-located with Pumped Storage Hydro (PSH) to meet the Day-Ahead (DA) schedule of wind generation. In the second application, a method for BESS sizing in the presence of PV-induced ramp rate limits is proposed. In this thesis, two methods based on Receding Horizon Control (RHC) for the optimal operation of the BESS are introduced. A co-located BESS and wind farm is considered in both methods. In one method, electricity market participation is not considered, and the goal is solely meeting the DA schedule utilizing the BESS. A novel predictive control method is proposed in this part and the efficiency of the method is evaluated through long-run simulations using actual historical wind power.

In the second scenario, market participation of the BESS is taken into account. The deviation from the DA schedule can be compensated through the BESS, or by purchasing power from the real-time electricity market. The optimization problem based on physical and operational constraints is developed. The problem is solved through an RHC scheme while using updated wind power and electricity price forecasts. In this thesis, a Ridge-regression forecast model for electricity price and an ARIMA forecast model for wind power are developed. Simulation results using actual historical data for wind power and electricity price demonstrate that the proposed algorithm increases the average daily profit. In order to evaluate the impact of the BESS lifetime and price on average daily profit, different scenarios are defined and simulated. Although they increase the complexity of the problem, much more realistic result might be obtained when all details and constraints are considered.

With the increasing attention and support behind plug in hybrid electric vehicles, research must be conducted to examine the impacts of vehicles on electric distribution and transmission systems. This research aims first to model the behavior of vehicle battery chargers during system disturbances and mitigate any impacts. A distribution test system example is modeled and several different vehicle charger topologies are added. Faults are applied to the distribution system with vehicle chargers connected and the results are examined. Based on these results, a control strategy to mitigate their negative impacts is suggested. Photovoltaic panels are then added to the system and the study is repeated.

Several services that plug in hybrid electric vehicles are capable of providing to the electric system are presented in order to allow electric vehicles to be seen as an asset to electric systems rather than a burden. These services are particularly focused on an electric system such as might be found on a college campus, which in this case is represented by the Clemson University electric distribution system. The first service presented is dynamic phase balancing of a distribution system using vehicle charging. Distribution systems typically face problems with unbalance. At most large car parks, a three phase electric supply is expected even though current standardized chargers are single phase. By monitoring system unbalance and choosing which phase a vehicle is allowed to charge from, unbalance between phases is reduced in a distribution system. The second service presented is a decentralized vehicle to campus control algorithm based on time of use rates. Using time of use electricity prices, discharging vehicle batteries during high prices and recharging at low prices is explored. Battery degradation as well as limits placed by required vehicle range availability are included in the decision on whether to charge or discharge. Electric utilities will also benefit from a reduction of load at peak times if vehicles discharge back to the campus. A comparison with stationary battery energy storage is included.

This thesis presents a novel approach towards solving one of the nation’s electric and energy sustainability problems and will have a major impact on California’s energy policy in meeting its targets, regarding renewable energy and minimizing carbon footprint. The study focuses on examining the technical and economic feasibility of smart micro-grid with distributed generation (DG) system with renewable energy on a coastal city. It presents a method to increase power reliability, redundancy, efficiency and to decrease the greenhouse gases (GHG) emissions contributing to climate change and ensure environmental sustainability. This innovative idea of aggregating multiple micro-grids that encompasses renewable energy from solar and wind, and uses battery storage and natural gas turbine generation for grid stability is unprecedented, which has been demonstrated as part of the results of this study. The proposed system produces enough power to sustain a small city while selling its excess power to adjacent cities. Moreover, this system could adopt other energy sources, not constrained to solar and wind, to exploit an area’s particular renewable energy niche (micro-hydro, geothermal, tidal wave, etc.). It is important to note that this system is economically, socially and environmental friendly (pillars of sustainability), through energy resource diversification, while harnessing free and abundant energy. The results of this study can used in designing and implementing a smart micro-grid in any city to meet its renewable energy and sustainability goal.

This thesis investigates social impacts of charcoal use in households in the Tanzanian town Babati. In Tanzania a majority of the population use charcoal and firewood as their main energy source. A part from the environmental problems connected to charcoal use; there are also considerable social impacts on women’s daily lives. Cooking and collection of wood fuel are time-consuming and restricts the possibilities for women to work and study. The thesis includes an investigation on how the Tanzanian government tackles problems connected to charcoal use, social as well as environmental. The result shows that the Tanzanian government is working with charcoal related problems to some extent but as previous studies shows there are still more that can be done. The main efforts made concentrate on information campaigns and promotion of more energy efficient equipments. One important problem is however that wood fuel is the cheapest available energy source and hence the incentives to start using other, more sustainable, energy sources are very small. The thesis also investigates possibilities for Babati households to substitute charcoal use with renewable energy sources available in the town. The result shows that the possibilities to use renewable energy currently are very limited and mainly affordable to richer households.

Legislated renewable portfolio standards (RPSs) may not be the key to ensure forecast energy demands are met. States without a legislated RPS and with efficient permitting procedures were found to have approved and issued 28.57% more permits on average than those with a legislated RPS. Assessment models to make informed decisions about the need and effect of legislated RPSs do not exist. Decision makers and policy creators need to use empirical data and a viable model to resolve the debate over a nationally legislated RPS. The purpose of this cross-sectional study was to determine if relationships between the independent variables of RPS and insolation levels and the dependent variable of the percentage of permits approved would prove to be a viable model. The research population was 68 cities in the United States, of which 55 were used in this study. The return on investment economic decision model provided the theoretical framework for this study and the model generated. The output of multiple regression analysis indicated a weak to medium positive relationship among the variables. None of these relationships were statistically significant at the 0.05 level. A model using site specific data might yield significant results and be useful for determining which solar energy projects to pursue and where to implement them without Federal or State mandated RPSs. A viable model would bring about efficiency gains in the permitting process and effectiveness gains in promoting installations of solar energy-based systems. Research leading to the development of a viable model would benefit society by encouraging the development of sustainable energy sources and helping to meet forecast energy demands.

The development of better energy conversion and storage devices, such as fuel cells and batteries, is crucial for reduction of our global carbon footprint and improving the quality of the air we breathe. However, both of these technologies face important challenges. The development of lower cost and better electrode materials, which are more durable and allow more control over the electrochemical reactions occurring at the electrode/electrolyte interface, is perhaps most important for meeting these challenges. Hence, full characterization of the electrochemical processes that occur at the electrodes is vital for intelligent design of more energy efficient electrodes.

X-ray absorption spectroscopy (XAS) is a short-range order, element specific technique that can be utilized to probe the processes occurring at operating electrode surfaces, as well for studying the amorphous materials and nano-particles making up the electrodes. It has been increasingly used in recent years to study fuel cell catalysts through application of the Δ&mgr; XANES technique, in combination with the more traditional X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) techniques. The Δ&mgr; XANES data analysis technique, previously developed and applied to heterogeneous catalysts and fuel cell electrocatalysts by the GWU group, was extended in this work to provide for the first time space resolved adsorbate coverages on both electrodes of a direct methanol fuel cell. Even more importantly, the Δ&mgr; technique was applied for the first time to battery relevant materials, where bulk properties such as the oxidation state and local geometry of a cathode are followed.