Mahinsasa Narayana

Impact of electric vehicles on power distribution networks

The market for battery powered and plug-in hybrid electric vehicles is currently limited, but this is expected to grow rapidly with the increased concern about the environment and advances in technology. Due to their high energy capacity, mass deployment of electrical vehicles will have significant impact on power networks. This impact will dictate the design of the electric vehicle interface devices and the way future power networks will be designed and controlled. This paper presents the results of an analysis of the impact of electric vehicles on existing power distribution networks. Evaluation of supply/demand matching and potential violations of statutory voltage limits, power quality and imbalance are presented.

Demand and supply analysis of community type wind power system at Gurugoda Village in Sri Lanka

Though expansion of the main grid is the principal vehicle for electrification, wind and solar home systems and community-level independent grids are frequently better suited to serve remote, rural communities in an economic and efficient manner. According to present statistics solar and wind home power systems are commonly used for off-grid electrification and solar home systems are much popular in the country. More recently a small wind power system was installed at Gurugoda Village in Northwest region of Sri Lanka. This system was installed to supply electricity for 13 houses. Focal point of this study is analyzing the wind power system with considering available wind resources and electric energy demand. This wind/battery system was analyzed by making energy balance calculations for each of the 8,760 hours in a year simulating the operation of the system. For each hour, the electric demand is compared with the energy that the system can supply, and the flows of energy from each components of the system are calculated. For systems that include batteries, for each hour the simulation process can decide how to charge or discharge the batteries. Time series wind resource data, power curve of wind turbine, battery efficiency, demand pattern and demand variation were considered for this simulation. According to the results of this study, from May to October there is a good wind potential and electric production of wind turbine is sufficient to fulfill the demand. However, there may be an electric supply shortage in February, April and November.

Electric vehicles as storage devices for Supply-Demand management

The use of electric vehicles as storage devices is investigated, with a view to improving the supply/demand matching of electrical networks. Consideration is given to making this supplementary function compatible with the primary function as a means of transport. Case studies showed that, where solar energy is the primary energy source, daytime charging, combined with evening/overnight regeneration, provides the optimum matching. Large car parks, close to the place of work, would be used for charging. Conversely, for wind energy, charging is generally best carried out overnight. This would therefore be performed largely in residential areas. Network reinforcement would include extra transformers for MV feeders to car parks, and higher capacity LV feeders in residential areas.

Graphene in the Form of Liquid Suspension by Shear Exfoliation of Liquids: Stability Study of Gasoline, Diesel, Kerosene and Water Based Nanofluids Containing Graphene Nanolayers

Nano fluids consist of thermal conductivity enhancement compared to the base fluid, but the cost of synthesizing of nanoparticles hinders its industrial applications. Recently, it was found that graphene nanolayers can be obtained by shear exfoliation of liquids. Moreover, graphene synthesizes by relatively abandon material graphite. In contrast to conventional heat transfer liquid like water, nanofluids are not transparent to solar thermal applications. It has been proven beyond doubt that kerosene, diesel and gasoline based nanofluids heat transfer coefficient enhancement would improve their efficiency of applications. In this paper water, kerosene, gasoline and diesel based nanofluids containing graphene nanolayers were prepared by shear exfoliation of fluids. Presents of graphene nanolayers were confirmed by scanning electron microscopic images. A spectrophotometer used to measure the stability of water, kerosene, gasoline and diesel nanofluids. Absorption of water-graphene nanofluid was examined to analyze the effectiveness of water based nanofluid for the solar collectors.

Levelised cost of energy analysis: A comparison of urban (micro) wind turbines and solar PV systems

The relatively high capital cost associated with micro wind energy systems and the resulting long payback periods, makes for a challenging argument for these technologies. However, as the global population becomes increasingly concentrated in urban areas, the potential for accessing any available renewable energy resource, including wind and solar PV, could become a necessity. This infers that the economics associated with small/micro energy systems need to be better appreciated. This paper presents a levelised cost of energy (LCOE) analysis for rural/urban small/micro wind energy systems that is contextualised by a solar PV system comparison. Further insight is offered through a design of experiments (DOE) consideration that affords an understanding of how system parameters, such as primary energy (rural/urban wind resource and solar insolation), capital cost and loan/finance interest rate individually and collectively affect the respective technologies. The results suggest that from an economic justification perspective, urban installations are difficult to justify and solar PV systems, with the associated lowering system costs, are challenging the viability of small/micro rural wind energy systems.

The impact of the upwind angle for a wind-driven iron smelting furnace in Sri Lanka

Sri Lanka was the worlds leading iron exporter around 3000BC. In 1990, the Samanalawewa archaeological survey identified forty one ancient iron smelting furnaces positioned along the western edge of the foothills and driven by natural draught. These furnaces functioned by heating the air within them thus reducing its density and causing it to rise. Unheated air was then drawn to the furnace through tuyeres. Ideally the natural draft can create high airflow rates if the resistance within the furnace is low. Therefore it is important that the furnace design-parameters are optimized to facilitate the combustion process to produce both low-carbon bloomery iron and high-carbon steel. The upwind angle generally depicts the wind direction and its impact in turn decides the tuyer parameters. The objective of this study was to quantify the effect of parameters for published data using statistical methods and, to analyze the cold flow of 2D geometry using CFD at steady state conditions for different upwind angles in OpenFOAM software. The simulation results indicated that the mean velocity across the furnace increases with the angle and the combined effect of the upwind angle and wind speed significantly affect the flow rate through the furnace.

Performance analysis of updraft gasifier

Biomass is becoming very tremendous and promising renewable energy source in the world over usage of fossil fuel. However it is still necessary to identify points of origin and quantity of generation to recognize the unknown potential of biomass energy source. Mangoes are cultivated in tropical climates throughout the world enabling enjoying it all over the year. Large-scale productions are carried out to produce various food types such as chutney, pickles, jelly, juice, smoothie and ice-cream in industrial scale. As a result mango pit which is one form of biomass generated basically as an industrial waste. Therefore mango pit can be utilized to generate energy by applying an appropriate technology of energy generation. In addition Coconut shell and Gliricidea are already established biomass energy sources in Sri Lanka. This study intends to develop an updraft gasifier for mango pits and compare performance with Coconut shell and Gliricidea. Considering abundant availability of mango pit, it has been introduced as a new biomass energy source to Sri Lanka. A laboratory scale updraft gasifier was designed and fabricated to conduct experiments. Results show that conversion of mango pit into producer gas by gasification is giving an efficient energy recovery at this stage and is a good solution for large scale mango pit waste produced from related industries.

Adaptive prediction of power fluctuations from a wind turbine at Kalpitiya area in Sri Lanka

Hydro power is the major renewable energy contributor to the national grid in Sri Lanka amounting to 48% of the total installed capacity. Further expansion of hydropower however is limited due to environmental and resource constraints. Meanwhile the demand for electricity is estimated to rise at an annual rate of 8% - 10% prompting the need to find alternative power options. The wind energy has been identified as a promising candidate to generate electricity in Sri Lanka. However for a reliable integration of wind energy the volatile nature of wind has to be understood. Wind speed-time series data typically exhibit autocorrelation, which can be defined as the degree of dependence on preceding values. Generally, statistical models and neural network techniques are being used for time series analysis. Present study shows how an adaptive digital filter can serve as a modelling, forecasting and monitoring technique, and, how they contribute to a successful integration of wind power into the national grid. The north-western region of Kalpitiya has been identified as one of the potential location for wind power generation in the country. This study also predicts power generation and investigates power fluctuations for grid integrations of a commercially available wind turbine installed in Kalpitiya area by using measured wind speeds and performance of the wind turbine.