KR Webzine Vol.147

The use of hydrogen energy on a ship can be divided into two categories. One is a technology to transport hydrogen, and the other is a technology for power generation onboard using a fuel cell system. The "Roadmap for Activating the Hydrogen Economy," published by the Korean Government in January 2019, includes development strategies for both these categories.

The transportation of hydrogen by ship could offer a practical method for very large quantities and long-distance or international transport. Hydrogen can be transported via ship in the form of ammonia (NH3), organic compounds (LOHC: Liquid Organic Hydrogen Carrier) or liquid hydrogen (LH2). In this field, Japan is leading the way in developing technologies. Korea started its research to transport hydrogen in a liquid state, in 2016.

Fig. 1 Hydrogen strategy in Japan (source: METI)

To develop the liquid hydrogen tanker, the first and foremost step is to develop and secure core technologies such as cryogenic insulation technology, loading/unloading technology, and BOG treatment technology. In Korea, a cargo containment systems (CCS) has been developed to hold liquid hydrogen on a liquid hydrogen tanker. The project has been developed through an R&D project led by KR. Three major shipbuilding companies (Samsung Heavy Industries, Hyundai Heavy Industries, and DSME) and related manufacturers and universities have participated in the project. The necessary parameters and simulation results for the design and the test regulations were established for ship application. The next step is to secure the other core technologies and then to construct a demonstration ship which can be tested to verify its safety. Once this has been achieved, liquid hydrogen tankers could be commercialized as soon as 2030, and the hydrogen economy would commence as planned.

In the shipping industry, fuel cell power generation systems are emerging, offering higher efficiency, and therefore lower fuel consumption and lower emissions, compared with conventional combustion engines.

Fig. 2 Basic design of membrane-type CCS (source: SHI)

Hydrogen fuel cells are systems that generate electricity and heat through electrochemical reactions between hydrogen and oxygen. A fuel cell system onboard can eliminate NOx, SOx and particulate material (PM) emissions, and reduce CO2 emissions. Other advantages of a fuel cell system for vessel power generation include noise and vibration reductions and the opportunity to use a modular and flexible design.

A hydrogen fuel cell ship is a ship that is propelled by electric motors using electricity generated by the fuel cell system onboard. For fuel cell system efficiency, pure hydrogen is preferred as a fuel, however, the storage method of fuel onboard needs to be considered.

Hydrogen has the highest gravimetric density, hydrogen energy content on a mass basis is around 120 MJ/kg, which is 2.5 times higher than that of natural gas and 2.8 times higher than that of diesel. However, on a volume basis, hydrogen contains around 8.5 GJ/m3(in case of liquid hydrogen), which is equal to two-fifths the energy of natural gas and one-fifths the energy of diesel, so hydrogen offers the lowest volumetric energy density. Considering the space constraints on commercial ships, one of the challenges of fuel cell applications onboard is to store enough volume of hydrogen.

There are several options to store hydrogen onboard: compressed hydrogen, liquid hydrogen, LNG, methanol, metallic hydride or LOHC. The most suitable method should be selected taking into account the voyage profile and ship type.

Fuel cell ships have already begun to be demonstrated, mainly in the EU and the US. Although Korea is somewhat late, it has the world's best fuel cell and ship design technology.

Furthermore, the Korea government has selected fuel cell ship technology as one of the promising future items in the shipbuilding industry sector, and as a result rapid development with government support is expected.

More than 30 demonstration projects applying fuel cell onboard vessels have been carried

Fig. 3 Demonstration of fuel cell module provided Power Cell

out to date around the world, mainly for small vessels. At the same time, gradually technologies for large vessels are being developed.  At present, ABB-Ballard and Siemens-PowerCell are leading the market through their technical alliances.

In Korea, several projects to apply fuel cells to ships have been carried out with government support. KR has taken part in some of these projects, including ‘Development of fuel cell system for marine auxiliary power unit (2011)’, ‘Development of enabling technology for hybrid power source (2011)’, ‘Development and demonstration of a 50kW PEMFC-battery hybrid system for the propulsion of cruise ships (2012)’, Since 2017, KR has led a government funded project entitled ‘Development & demonstration of PM (Particular Matters)-free PEMFC hybrid system for ship’ for the fuel cell demonstration onboard.

Korea has the world's best fuel cell technology and shipbuilding technology although there is no experience of combining these technologies, and there is a lack of a hydrogen infrastructure to expand the market. However, as there are more and more collaborations between fuel cell companies such as Hyundai Motors and Doosan, shipbuilding companies and shipbuilding equipment companies in Korea, and the government is making efforts to create the related industrial ecosystems, and we believe that as a result, Korea will be able to lead the technology much faster than expected.

Fig. 4 Image of LH2 carrier (source: KR)

Fig. 5 Image of hydrogen fuel cell propulsion ship (source: KR)