Optimal Method of Generating Power at the Train Rooftop for the Auxiliary Power Supply System Case Study: Solar and Wind Power Generation on Electric Multiple Units (EMU) at Addis Ababa Light Rail Transit System (AALRT)

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Addis Ababa University


This research aims at exploring the optimal method of generating energy on the rooftop of the train when it’s in motion, for the case of Addis Ababa Light Rail Transit system (AALRT).The sources of energy considered are solar and wind energy. The collected energy can be used to power the auxiliary services like air conditioning, door opening and closing, LED display and others. To be able to achieve this, the solar and wind resource assessment was done for Addis Ababa to assess the viability of this project. It was found out that Addis Ababa receives 4kWh/m 2 /day to 7kWh/m 2 /day annually. The ambient wind speeds are rather low for wind energy harvesting and i.e less than 2 m/s. From the literature reviewed, the induced wind speeds are almost half the vehicle speed which is about 4m/s. This is still low and therefore a ducted turbine was recommended. This would increase the wind speed to 15m/s which is sufficient for energy generation. It was found out that 21 solar panels would be installed that would be able to generate 24.6kWh/m 2 /day and using a ducted turbine would increase wind power generated from 73.3W to 3.8kW. The solar and wind system components were sized and representative components i.e. components with similar specifications were selected from HOMER (Hybrid Optimization Model for Multiple Energy Resources) and cost optimization and sensitivity analysis were done. Optimization results obtained indicated solar would be more cost effective than wind with Cost of Energy as 0.0947. To simulate the actual conditions on ground, the system was connected to the grid and it was still realized that using solar would be more cost effective than using wind or grid connection. In fact, when the system is connected to the grid, the cost of energy increases to 0.251. This further confirmed that using solar energy is still the most optimal method. In the end, it was recommended that for wind energy, the project would be more viable if implemented on the Ethio-Djiboute line which has relatively higher vehicle speeds and few vehicle stopovers as compared to AALRT. However, solar energy can be implemented at AALRT since it’s able to supply for sufficient power at minimal cost.



Auxiliary Power Supply System, Solar and Wind Power Generation, Electric Multiple Units (EMU), ddis Ababa Light Rail Transit System