As marine litter and debris emerge as a serious environmental problem, a group of researchers in Busan, South Korea, is introducing an environmentally-friendly ship technology to clean up the ocean.  Professor Jae-myung Lee talks to Sunny Um, South Korea correspondent, Maritime Fairtrade.

As of 2018, the country collected almost 10 metric tons of marine rubbish.  This amount has been on a constant rise since 2015, according to the South Korean Ministry of Oceans and Fisheries. 

Since the late 1990s, the government has launched many policies to mitigate the problem, ranging from regular monitoring of littering at the coastal waters to sending out cleaning ships to collect the floating and underwater rubbish.

However, some experts have criticized that these dispatched clean-up ships are also responsible for contaminating the environment themselves. This is because many ships operated with fossil fuel, a major air and ocean pollutant. Also, most of the collected marine rubbish is burnt or buried instead of being recycled.

To solve this problem, a research center at Busan, South Korea, designed a clean-up ship run by zero carbon emission fuel: liquefied natural gas (LNG) and hydrogen. The ship also disposes the collected garbage in an eco-friendly way, e.g., upcycle the collected marine rubbish.

Prof. Jae-myung Lee, head of the Hydrogen Ship Technology Center (HydSTC) at Pusan University, talks about the details of the center’s cleaning ship, which has been designated as a nation-level government project this year.

Would you briefly introduce what type of research HydSTC does?

HydSTC is a research center that studies vessels that store and transfer hydrogen fuel and hydrogen fuel cell propulsion ships. Recently, one of our projects is to build an eco-friendly ship for the collection and process of marine rubbish and it has been designated as a government project. So, we’re working hard on it.

Can you tell us more about this eco-friendly ship?

Many countries, including South Korea, are interested in processing marine rubbish and reducing carbon emission. However, the current marine rubbish clean-up ships cannot do them both at the same time, which is creating a vicious cycle of environmental pollution.

I thought a solution for this was combining the following techniques: replacing heavy fuels with LNG-hydrogen hybrid fuels, and freezing and crushing the collected rubbish with LNG’s cold energy on the ship.

Freezing, brominating, then fragmenting marine rubbish, especially plastic products, at extremely low temperature (with the use of LNG) is found to be more efficient than smashing it at room temperature. This in-ship disposal process also does not require additional fuel, as it uses cold energy from the vessel’s fuel, making the cost more reasonable.

Our ship also includes upcycling the marine rubbish for construction uses, for example, making a walking path. It is more eco-friendly as workers won’t have to process them through burning or burying.

Please tell us more how the in-ship rubbish processing work.

The proposed ship adopts some features of LNG-fueled vessels. LNG is stored at minus 163 celsius degrees. To be used on a vessel, its temperature needs to increase and normally, in the process, the cold energy is disposed off. But our proposed ship uses this energy to freeze and smash the marine rubbish.

Using LNG’s cold energy can fragment the rubbish at a higher efficiency rate than physical fragmentation. Also, smashing the rubbish pieces are good for removing salt and moist, without which the end products are suitable for recycling or upcycling.  The energy that the ship needs in the disposal process will be supplied by non-polluting hydrogen fuel cells.

The unique feature of the ship is that we can collect and process marine rubbish on the spot at the same location by using eco-friendly fuels.

How effective will the ship be in reducing marine rubbish?

Our ship is expected to process a maximum of 10 metric tons of rubbish per day. If we operate this ship for 100 days, it will need 1.7 billion won (US$1.5 million) for fuel costs, labor costs and other expenses. We expect this ship to dispose about 1,500 metric tons of marine rubbish per year.

What are the challenges you face for this project?

One challenge is to integrate all the different technologies and make them work seamlessly including the marine rubbish disposal and recycling system and LNG-hydrogen hybrid propulsion system, among others. 

The technology using the cold energy from LNG to process rubbish is essential.  As this is a field that is still relatively new and has not seen much research, I will like to engage in more study.  Still, as we are a world-class research center, we won’t have much problem building the ship. 

We also hope to see more interest and support outside of South Korea, as environmental pollution is an international problem.