Yes / Clean water demand has significantly increased due to the rise in the global population. However, most water on the Earth has high saline content that cannot be consumed directly; only about one over forty of the total water source is freshwater. Desalinated water is one of the potential solutions to meet the growing demand for freshwater, which is highly energy intensive. This paper analyses the energy, economic and environmental performance of a 5 m3/day PV (photovoltaic) powered reverse osmosis (RO) desalination system. Three scenarios of PV-RO with and without battery storage and diesel generator hybrid systems have been analyzed and investigated for the annual estimate load, net present value, and payback period of the water and electricity production costs. Also, the CO2 avoidance over the lifetime operation of all scearios is evaluated. This study shows that the PV-RO system without battery with 6.3 kW PV panels installed and with a 2-days water storage tank system is the most profitable economically f. For this scenario, the Levelized Cost of Electricity (LCOE), Levelized Cost of Water (LCOW), and Payback Period (PBP) are found to be $0.154/kWh, $0.627/m3, and five years, respectively. In addition, for this scenario, the CO2 emissions avoidance was the maximum (111,690 kg.CO2eq per year) compared to other scenarios.

Master of Science / Department of Electrical and Computer Engineering / Anil Pahwa / In Afghanistan, electricity is mostly generated by hydroelectric, diesel and natural gas generators. A significant amount of electricity also is imported from neighboring countries. Accessibility of electricity is mostly limited to the capital and main towns. The government of Afghanistan and other development organizations, such as The United States Agency for International Development (USAID) and Deutsche Gesellschaft für Internationale Zusammenarbeit (German Agency for International Cooperation “GIZ”), are striving to develop accessibility of electricity to remote communities by supporting the local population of people to enhance living conditions. Although some of these remote communities are served by local diesel fuel generators for just a couple of hours during the night, still most communities do not have access to electricity and they are using wood and kerosene as major sources of energy in cooking, heating and lighting. For those remote communities who are served by local diesel fuel generators, the cost of electricity is much higher than from the national grid. On the other hand, grid extensions are too expensive and, in some cases, impossible for such communities because of the geographical features of Afghanistan. Afghanistan is a mountainous country which receives a significant amount of snow during the winter and once it melts the water runs into rivers, lakes and streams. Therefore mostly it does not face any shortage of running water during the year. Also Afghanistan has plentiful wind and solar energy. Therefore, small hydro-power, wind turbine and solar energy are attractive renewable energy sources for remote communities. The development of such a hybrid power system is a complex process and technical expertise is essential in design and construction phases. The main challenges are the high cost of civil works and equipment, technical expertise for design and construction and encouragement of local people for the support of the project. This report will give an insight into design, cost-effectiveness and feasibility of the system using HOMER in order to encourage private investors and local community people to take advantage of this potential available in Afghanistan and be convinced of the sustainability for investments in micro-hydropower, wind and solar.

This thesis describes a systematical study, including multidisciplinary modeling, simulation, control, and optimization, of a fuel cell - gas turbine hybrid power system that aims to increase the system efficiency and decrease the energy costs by combining two power sources. The fuel cell-gas turbine hybrid power systems can utilize exhaust fuel and waste heat from fuel cells in the gas turbines to increase system efficiency. This research considers a hybrid power system consisting of an internally reforming solid oxide fuel cell and a gas turbine. In the hybrid power system, the anode exhaust, which contains the remainder of the fuel, is mixed with the cathode exhaust as well as an additional supply of fuel and compressed air and then burned in a catalytic oxidizer. The hot oxidizer exhaust is expanded through the turbine section, driving an electric generator. After leaving the gas turbine, the oxidizer exhaust passes through a heat recovery unit in which it preheats the compressed air that is to be supplied to the fuel cell and the oxidizer. This research concentrates on multidisciplinary modeling and simulation of the fuel cell-gas turbine hybrid power system. Different control strategies for the power sharing between the subsystems are investigated. Also, the power electronics interfaces and controls for the hybrid power system are discussed. Two different power sharing strategies are studied and compared. Simulation results are presented and analyzed. Transient response of the hybrid energy system is studied through time-domain simulation. In addition, in this effort, Particle Swarm Optimization (PSO) is used to optimize the power sharing for the hybrid power system to increase the efficiency and decrease the fuel consumption.

The ever increasing demand for electricity has driven society toward the installation of new generation facilities. Concerns such as high costs associated with installation of new facilities, environmental pollution, higher transmission and distribution losses, depleting fossil fuels has created a lot of interest in exploring the renewable energy sources for generation, particularly near the load sites. Accordingly, emphasis has been put on Wind, and Photovoltaic (PV) energy systems. A study on the operational characteristics of these systems reveals that the power generation is high at certain optimal points and recognizing these optimum points and operating the system accordingly is an interesting and important part of the system design. Further, a hybrid Wind- PV system has higher reliability and generation capability when compared to either source alone, and as a result many such hybrid systems with an additional energy storage backup for increased reliability have been proposed. While the systems with energy storage are reported to have satisfactory performance, the energy storage component is typically found to incur the highest cost, requiring frequent maintenance and hence acts as a deterrent for increasing the renewable energy generation. Particularly, for small grid connected applications like shopping malls, office buildings, etc. any additional power that could not be provided by the hybrid system could be provided by the grid, and in case the power generation is higher it could be sent to the grid. For cases like this, it would be ideal if systems could be developed without energy storage, and maximum possible power could be extracted from the hybrid energy sources. Also, the power quality concerns posed due to the random nature of the power generated from the hybrid system, is an important issue that must be addressed. The conventional control methods used typically require overly sized component ratings, resulting in the degradation of the dynamic performance while adding to the cost of the system. This dissertation addresses these issues by proposing faster maximum power extraction algorithms from the hybrid renewable energy system, and proposes new control architecture for improving the output power quality to the grid.

Government of Sri Lanka has policy target to achieve 100% electrification by end of year 2012. Grid-based electrification is possible up to maximum 95% of the population in Sri Lanka. Balance 5% of the electrification has to be mainly depending on off-grid technologies such as solar PV, wind, biomass and micro hydro.   Use of renewable based off-grid technologies is limited by the seasonal variation of the resource. This barrier could be overcome by coupling renewable based power generation technologies with a diesel generation thereby forming a hybrid power system. Given the comparatively higher investment cost, a hybrid power plant needs to be carefully designed and optimized to generate electricity at competitive prices.   There are some Isolated Islands located in the Jaffna Peninsula (Northern part of Sri Lanka) called Eluvaithivu, Analaithivu, Nainathivu and Delft Islands. These islands are far away from mainland. At present diesel generators are supplying electricity to these islands for limited hours. Electrification rate of these islands are very low due to the Grid limitations. Also cost of electricity generation is very high due to the high diesel price.   The main objective of the present study is “Selection of optimized mix of renewable based power generation technologies to form a mini-grid and to supply reliable, cost effective electricity supply to the people living in Eluvaithivu Island’ and thereby support the 100% electrification target by Govt. of Sri Lanka in 2012.   Data collection, survey has been conducted in the Eluvaithivu Island to find out the status of present system, priority needs, resource data and load data to propose suitable power system for this Island. An extensive analyse was conducted using HOMER software model and the result is presented in the report. Optimum design emerges as a wind-diesel hybrid power system having wind turbines generator, diesel generators, battery bank, converter and a hybrid controller.   The result revealed that the economic viability of the project, in the form of a community owned wind-diesel hybrid power system operated on cost-recovery basis is not feasible. But it is an attractive option for CEB to reduce its long term losses on diesel fuel. In other words, if CEB implement this project, it would be an ideal win-win situation where both the CEB and the island community are benefited.

No description available.

Efficiency is a driving constraint for electrical power systems as global energy demands are ever increasing. Followed by the introduction of diesel generators, electricity has become available in more locations than ever. However, operating a diesel generator on its own is not the most energy efficient. This is because the high crest factor loads, of many applications, decrease the fuel efficiency of a hydrocarbon generator. To understand this, we need to understand how an electrical load affects a generator. Starting with a load profile, a system designer must choose a generator to meet peak demand, marking the first instance where a load profile has influence over a generator. This decision will insure that brownouts do not occur, but, this will lead to poor energy efficiency. We say this because a generator is most energy efficient under heavier loads, meaning, during lighter loads, more fuel will be consumed to produce the same amount of energy. While this may be fine if the peak load was close to the average load, however, the actual crest factor for a typical residential load profile is much higher. This gap between peak and average load means that a generator will spend most of its time operating at its most inefficient point. To compensate for this, and reduce fuel consumption, the Mechatronics Lab at Virginia Tech has developed a mobile hybrid power system (MHPS) to address this problem. The solution was to augment a diesel generator with a battery pack. This allowed us to constrain the generator so that it only operates with fixed efficiency. It is the theory behind this system that will be covered in this thesis. / Master of Science

Diesel engine and generator sets (gensets) have been extensively used for standby and remote power generation over the past hundred years. Due to their use for standby power, these diesel gensets are designed to operate in conjunction with the grid, which relates to a fixed speed operation with a 60 Hz AC output. For operation in remote conditions, such as military and disaster relief applications, this fixed speed operation results in limiting the power output available from the engine, as well as the overall efficiency of the system. The removal of this grid connectivity requirement could result in an increase in system efficiency. At a given load, the engine operates more efficiently at lower speeds, which corresponds to an increase in the system efficiency. This low speed operation also results in lower power output. Knowledge of the load is important in order to determine the most efficient operating point for fixed speed operations. Operating at a higher power output for a given speed also results in higher system efficiency. The addition of a battery pack will allow for a higher apparent load, resulting in higher operating efficiency. The addition of a battery pack will also allow for energy storage, which allows for a higher operating efficiency, as well as "engine off time". A controlled series capacitor converter should be used to ensure that the maximum power is transferred from the genset to the battery/load. Knowledge of the load and equipment available should be used in order to determine the ideal dispatch strategy. Overall, operation at the grid frequency limits the efficiency of the overall system for remote operations where grid frequency is not required. The simulated genset had an efficiency of 24% for a 3 kW when operated at 1800 RPM, and increase from the 17% efficiency at it normal operating speed of 3600 RPM. This corresponded to a fuel savings of 3 gallons over 24 hours of continuous operation. When a battery is incorporated into the system, the efficiency of the system will increase for a given output load. For example, the simulated genset has an efficiency of 15% for a 1 kW load, which increases to 24% when a battery is added and charged at 2 kW. / Master of Science

This thesis is a study on integration of photovoltaic generators into an existing diesel-unreliable grid connected system at the Lebanese village of Khiam. The main goal of implementing PV-diesel hybrid system is to reduce diesel consumption and the import of fossil fuel used in electricity power supply. Before designing the system, it is necessary to create a load profile for 120 households and pre-design the size of the PV generator, the capacity of storage system and inverter type/size selection. The load profile data is based on the average of monthly energy consumption gathered from Khiam village households. Detailed simulations and financial analysis are performed with HOMER to compare different systems and their viability. The simulations include four different designs starting from the existing system, diesel generator with unreliable grid, followed by PV generator and unreliable grid, PV and diesel generator and ended with the complete hybrid system. Once the Hybrid system is determined a detailed design is done to optimize the lowest cost PV-diesel hybrid system. The final simulated PV-diesel hybrid system is suggested with a PV capacity of 270 kWp, existing diesel capacity with 200 kVA, an inverter output of 115 kW and battery bank nominal capacity is 1872 kWh. The system renewable fraction is 53% and the project life cycle is 25 years. The PV-diesel hybrid system is projected to produce electricity at a cost of 0.12 USD/kWh. This cost is significantly lower than the 0.26 USD/kWh paid to the diesel operator, as well as lower than 0.13 USD/kWh paid to the utility grid. In addition, and according to the given information from the owner, an estimated diesel consumption of 104000 ltr/year, the simulation result shows diesel consumption at 40000 ltr/year. The reduced carbon dioxide production by 65%, from 776 to 272 tons per year, provides further justification for the PV installation in a commercial PV-diesel hybrid system.

In this report, the modeling process and operation of an autonomous hybrid power system is studied. It is built based on a hypothetical case study of electrification of a remote village of 100 inhabitants in Kenya. The power demand is estimated and the costs of equipment components are specified after extensive research, so that the techno-economical design of the system can be carried out. The microgrid consists of photovoltaics, wind turbine, batteries, diesel genset, basic loads and water pumping and purification load. The system is modeled and simulated in terms of power management and its operation as well as the performance of the dispatch strategy is assessed. Problems like the management of extra power or tackling the deficit of power in the system are addressed. The model represents reliably the behavior of the microgrid and several improving actions are suggested.