Introduction

As the world shifts into a period of heightened environmental and social consciousness, it is becoming increasingly clear that an energy crisis is on the horizon as demand for energy continues to increase while traditional environmentally damaging fossil fuel sources are becoming increasingly scarce. A promising avenue can be found in vibration energy.

Sea Wave Harvesting

Our system can be used to harvest sea waves. To do so, the oscillating pole is inverted into a pendulum configuration without springs. A paddle is then mounted on the tip of the pole to capture the waves. A wave simulator is built to allow us to test various wave frequencies mimicking the conditions of the sea. A servo and multimeter are connected to LabView and Arduino interface to record the data. FFT analysis is done in IgorPro.

It is fascinating that due to the counter reflection of the water (similar to that on beach sides), we observed non-ideal wave oscillations with multiple frequencies depending on the frequency of incoming wave. Our goal is to try to engineer the system such that our system is in resonance with the incoming wave.

Out of all the trials, the highest output came from a wave servo delay of 5 ms/deg. However, the system can still be optimized as resonance was not achieved at a wave servo delay of 5 ms/deg although it gave the highest amplitude.

Testing and Analysis

Spring Oscillator for Absorbing Bridge Vibrations

The system as shown in the wave energy harvester setup on the left, consists of an oscillating pole that is connected to a pivot joint and electromagnets array.

Four sets of springs were mounted on the pole to enhance the vibrations generated when the pole is disturbed.

In this test, we have mounted 4 springs with 0.5 mm thick wire, coil diameter of 9 mm and length of 5 cm. Here the system was tested by pulling the tip of the pole sideways with 15 N or 5 cm away. Then, the pole was released, and the voltage was recorded over the course of 60 seconds.

The graphs on the left shows the AC voltage generated using various numbers of cells. We then use this information to obtain an equation that relates the number of cells to the predicted voltage, energy and power generated.

We estimated that to generate 100 mW per 15 N pull in a 60 second average, ~64 cells are needed.

If a bridge oscillates such that a 15 N force is acted upon the pole every minute, such system will generate energy of 2.4 W.h in a day.

Conclusion and Future Work

The highest peak-to-peak voltage is 18.5 V, yielded from a 6-cell setup.
Based on the equations of the lines above, the system will be less efficient as the number of cells is scaled up. Thus one must carefully calculate the cost trade off for implementing this system.
Resonance has not yet been found for the seawave harvesting setup, but the highest output came from a seawave servo motor delay settings of 5 ms/deg.
As an extension, the system could be adapted to scenarios like: foot traffic, wind, etc.
Currently, the design only works in 2 dimensions. Being omnidirectional would be more efficient.

Benedict Marco Kosasih

PUBLICATION AND PRESENTATION

EVENTS ATTENDED