Solar power on high seas

17 September 2015 | Research
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Bo Bo Cha Cha arriving safely at the ferry terminal in Bintan

Two NUS faculty, who were invited to present a paper on "Solar-Powered Sailing Yachts in the Tropics at a conference on the island of Bintan, Indonesia, thought it would be quite apt to arrive in Bintan in one such yacht.

As such, both Associate Professor Martin Henz from the University Scholars Programme (USP) and NUS Computer Science and Dr Joerg Weigl, Lecturer at the Design-Centric Programme (DCP) of NUS Engineering sailed to Bintan on their carbon-neutral motorised yacht, which relies only on wind and solar power for propulsion, to attend the first International Conference on Maritime Development held from 4 to 6 September. "What better way to demonstrate the viability of carbon-neutral yachting than to reach the island in a carbon-neutral way? said Assoc Prof Henz.

The yacht, christened Bo Bo Cha Cha, was designed by NUS' Team FrogWorks, a collaboration between USP and DCP students. It is currently the only carbon-neutral motorised sailing yacht in Singapore.

Year 4 USP students Cheang Kai Wen from NUS Psychology and Arianto Usman Adamy from NUS Business School as well as Year 3 DCP student Shawn Sim from NUS Mechanical Engineering joined Assoc Prof Henz and Dr Weigl on the almost 13-hour journey to and from Bintan. Although they were blessed with favourable weather conditions throughout most of the trip, the crew did hit some bumps.

"On our way to Bintan our electric motor came off its mount. The propeller hit the rudder and the shear pin protecting the propeller broke. However, we had the right tools and spare parts on board to carry out the repairs while continuing to sail. That's the advantage of hybrid transport; when one mode fails, you can fall back on the other, said Assoc Prof Henz.

In configuring the main components of the vessel, the team had to factor in the available solar irradiation, size and power requirements of the boat as well as the desired sailing range. The solar panels installed can fully charge the boat's lithium-ion phosphate battery sets in less than four days under typical light conditions in Singapore, allowing up to five hours of continuous full throttle operations. The solar charging data can also be monitored remotely by a new web interface. 

Although the yacht had travelled to Batam and Pedra Branca in December 2014 and January 2015 respectively, this is the furthest the yacht has sailed since its maiden voyage along the northern shores of Singapore last November.

Furthermore, on previous trips a combustion engine always served as a safety backup on board. This time, the team had a newly acquired electric motor as a spare, ensuring a completely carbon-neutral voyage ' that is, without the consumption of fossil fuel ' even in the case of failure of the main motor. In the tropics, solar-powered electric motors are attractive alternatives to combustion engines due to the abundant availability of solar energy all year round.

The team wants to make further improvements to the vessel, such as connecting more solar panels and refurbishing the electric wiring. Ultimately, they hope to travel to Christmas Island by next year.