A new ship project in the Philippines, a Bangka, hopes to be a low-carbon alternative, working powered by waves. The vessel is a hybrid model, using multiple internal combustion engines for initial propulsion but switching to wave energy during open water cruising.
The trimaran (or Bangka, as it is called) is a common sight on Philippine waters. The country exploited this design already in its first warships, then adopted it for its traditional sailing boats and fishing boats. As an island nation, the Philippines relies on boats, ferries and cargo ships to transport people and goods across its more than 7000 islands. But its fleet of cargo and passenger ships is one of the largest contributors to the country's greenhouse gas emissions. In 2012, transportation was the second largest source of greenhouse gas emissions in the Philippine energy sector, after heating and electricity.
Globally, 9% of all transportation emissions come from international and coastal shipping. This is a small figure next to the 72% coming from road transport, but puts transport on a similar level to aviation, which makes up 10,6% of transport emissions. And with the volume of world maritime trade that is expected to increase by 3,8% per year to 2023, emissions from the maritime sector are also likely to increase.
Unless the growth of maritime traffic cannot be dissociated from emissions.
Power of the sea
This project was born from an idea of Jonathan Salvador, maritime engineer and owner of the shipbuilding company Metallica Marine Consultancy, Fabrication and Services. Jonathan was immediately inspired by the traditional bangka design. “The job of the stabilizers is to provide stability so that the bangka does not tip sideways”, says Salvador. “But I also noticed that every time a wave hits the stabilizer, it constantly reacts to the up and down motion of the wave. What if we could convert this reaction, I wondered, into electrical energy? ”
The way wave energy works will be familiar to anyone who has wandered the sea waters. Sometimes they are strong enough to push you to shore or high enough to push you further. The hybrid trimaran has a wave energy converter in the form of hydraulic pumps integrated into its stabilizers. As the pumps move through the waves, they pick up the momentum of these waves, converting their kinetic energy into electrical energy. This energy will power a generator that will supply electricity to the ship. The more waves the trimaran encounters, the greater the power it can produce from those waves.
Bangka, the genesis
Construction of the hybrid trimaran began in 2018 and was completed in early 2020. A typhoon in 2019 delayed the project, and the Covid-19 quarantine put it on hold for a while. Despite these challenges, the team aims to finish construction of the vessel by the end of 2020, with a three-month sea trial scheduled for the first quarter of 2021. The ship is expected to be able to carry 100 passengers, four vans and 15 motorcycles.
It is hoped that the wave propulsion boat prototype will be the first of a series of increasingly ambitious projects that move away from fossil fuels.
The hybrid trimaran's use of wave energy could be a significant step toward reducing the need for environmentally harmful fuels like diesel in the Philippines. And with wave energy offsetting gasoline use, Salvador and his team aim to reduce the ship's carbon emissions one third compared to the most modern large-scale shipping lines.
The trimaran has the ideal shape
The wave energy converter benefits particularly from Bangka's traditional trimaran design. “Wave energy requires the movement of one part of the system relative to another,” he says Rob Cavagnaro, mechanical engineer at the Marine Sciences Laboratory of the Pacific Northwest National Laboratory in the USA. “Having stabilizers that can be raised above the central hull can be suitable for this purpose.”
In addition, the waves are dense with energy: they can be really powerful. On the coast, waves can reach power densities of 60-70 kilowatts per meter in deep water areas. In the UK and US, for example, the average wave power density is between 40 and 60 kW per metre. If you can translate that energy into other useful forms, you can do a lot with very little.
The challenges to face
Converting movement into energy efficiently can be a challenge. “There can be a lot of losses along the way, from friction in hydraulic systems to heat in the electric generator,” says Cavagnaro. The remaining engineering challenge is to minimize these losses. Another obstacle would be designing a wave energy converter small enough for the size of the ship. Wave energy converters generally develop more power the larger they are, but if they are so large that the waves can't move them, they can't actually gather momentum.
Nonetheless, a private company in Boracay, a popular tourist island in the country, has already expressed interest in operating the ship once launched, he says Rachel Havana, senior scientist at the Philippine Council for Industry, Energy and Emerging Technology Research and Development, who oversaw the development of the trimaran. “We envision the future of public maritime transportation in the Philippines to be safe and green with fewer emissions, and we see the trimaran bringing that vision to life,” she says.
There is a world of difference between saying and doing a Bangka
So far, let me not forget, the hybrid trimaran is still a prototype. “Because we have new technologies for the vessel, we need a technology verification phase before we can proceed to full-scale commercialization,” he says Yasmin Tyrol, project leader. “We have already conducted some test models for the wave energy converter, but we need to look at its actual performance and optimize it.”
Cost is another problem. Funding for the project is 76 million Philippine pesos (1,5 million euros), but Salvador estimates commercial-level costs to reach the equivalent of 5 million or more per vessel. To keep expenses low, at least 80% of the trimaran's parts are locally sourced, and the entire manufacturing and assembly process is done within the country.
The current one is a "series one" prototype. More ambitious and less expensive series are expected to follow, with wave energy used to almost or entirely power the vessel. True, the stronger the wave the more energy there is, but no one likes sailing at full speed through storms. Wave-powered ships are a nascent technology, and it is yet to be seen what the best way to draw energy from the sea is.
