Thailand’s state energy company PTT and Malaysian shipowner AET have hooked up together to develop and build a pair of zero-emission aframax tankers that will be capable of running on green ammonia.

The two companies said on Thursday that they have signed a memorandum of understanding on the pioneering newbuildings to encourage the use of green ammonia as a main propulsion fuel.

Under this AET will select a shipyard to build the vessels which will be ordered against long-term charters with PTT.

The newbuildings are due for delivery in the fourth quarter of 2025 and the first three months of 2026.

The companies did not give any details on where the green ammonia fuel for the vessels will be sourced from.

Ammonia engines are still under development with designer MAN Energy Solutions promising to have a first version for sale by the end of 2024.

The two companies said: “This MOU sets another clear signal of PTT’s and AET’s commitment to reduce greenhouse gas (GHG) emissions from international shipping as energy efficiency improvements alone will not be sufficient.”

Colours of ammonia
  • Grey or brown ammonia: Produced from fossil fuels.
  • Blue ammonia: Produced using natural gas, but with CO2 capture and storage.
  • Green ammonia: Produced from hydrogen made through the electrolysis of water using renewable energy.

AET has been an early mover on new fuelling types. The company built the world's first LNG-fuelled VLCC for TotalEnergies and has been working to promote green ammonia as a fuel with its partners in The Castor Initiative set up to make zero-emission in shipping a reality.

Castor Initiative partners Lloyd’s Register, Samsung Heavy Industries and MISC Berhad, via its tanker subsidiary AET, signed an MOU in April for two ammonia-fuelled VLCCs with similar delivery targets to the aframax tankers.

PTT International Trading Business senior vice president Disathat Panyarachun said: “ .. we are both aligned that the global shipping community must act now and we see green ammonia powered vessels as one of the pathways to achieve the decarbonisation goals.”

AET President & chief executive Capt. Rajalingam Subramaniam, who is also MISC Group COO and incoming CEO, said: “This MOU signing marks another significant milestone in our growing partnership with PTT as we both place great importance on driving the shipping decarbonisation journey ahead of 2050.

He said the collaboration goes beyond these first two net-zero green ammonia-powered aframaxes, mentioning working together on the design, safety and operational aspects of the vessels, reskilling of mariners and creating a green ammonia corridor in Southeast Asia.