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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Date
2019-07
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Addis Ababa University
Abstract
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.
Description
Keywords
Auxiliary Power Supply System, Solar and Wind Power Generation, Electric Multiple Units (EMU), ddis Ababa Light Rail Transit System