Japanese trio’s Direct Ocean Capture pilot targets synthetic fuel production

Japanese conglomerate Hitachi, shipping company Mitsui O.S.K. Lines (MOL) and airline Japan Airlines (JAL) will jointly carry out Japan's first pilot project using Direct Ocean Capture (DOC) technology to remove carbon dioxide (CO2) dissolved in seawater.

IMAGE: Conceptual illustration of DOC. MOL

The pilot will be conducted on Kume Island in Okinawa Prefecture and marks the country's first demonstration of the technology.

DOC works by extracting dissolved CO2 directly from seawater. Because the ocean naturally maintains a balance with atmospheric CO2, removing carbon from seawater encourages it to absorb additional CO2 from the atmosphere. Repeating this process enables indirect removal of atmospheric CO2. Seawater contains roughly 100-150 times more CO2 than the atmosphere, making it an attractive medium for carbon capture, according to the companies.

DOC has the potential to become a cost-effective and energy-efficient carbon removal technology, the partners said.

They see the pilot as an initial step toward creating a self-sustaining carbon economy on islands, where captured CO2 could eventually be used as a feedstock to produce synthetic fuels. The technology could be particularly valuable for hard-to-decarbonize sectors such as shipping and aviation, where emissions are difficult to eliminate through electrification alone.

The pilot will use a containerized land-based system on Kume Island to process seawater and separate dissolved CO2. The partners aim to evaluate the practicality of DOC under local conditions while collecting data on operational performance and potential environmental impacts to support future deployment along Japan's coastline.

Based on the results, Hitachi, MOL and JAL will assess broader applications of the technology, including local uses for the captured CO2.

MOL has been increasing its investment in e-fuel projects, which use captured CO2. In 2024, MOL invested in the e-methanol production plants of US-based renewable fuel producer HIF Global (HIF) in the US, Australia, Chile and Uruguay. Part or all of the e-methanol produced at these facilities is expected to be exported to Japan, where it will be used as bunker fuel in shipping or in other industries.

By Tuhin Roy

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