From concept to reality
Building a shipboard CCS plant has been a long and exciting voyage – from a ”non-possible” starting point to a future-proof running installation.
«When we signed the letter of intent for onboard carbon capture back in 2021, all we had was a plan on the paper and a good understanding of what we needed», fleet director Tor Øyvind Ask in Solvang says.
Running a fleet of gas carriers fuelled by conventional fossil fuel oil, Solvang managed to mitigate most emission factors. Including NOx, SOx, and particles. The remaining CO2 was the missing link.
«Changing to low-carbon fuel was not a realistic option, as it only meant CO2 emissions would shift to other parts of the value chain. In addition, the price of alternative fuels would price us out of competition. So we went for a radical solution to capture the CO2 post-combustion and keep conventional fuel. Which nobody had done before», Mr. Ask says.
Engineering challenges
Solvang initiated studies in collaboration with the Norwegian flag, Wärtsilä, MAN, DNV and Seatrium. This turned into real feasibility studies by year-end -22. Test running at Wärtsilä’s facility in Moss, Norway, produced promising results. In 2023, Norwegian state environmental agency Enova supported the project for maritime testing. «We got less than a year to prepare the technology for real-time operations», says Kai Heine Sirevåg, Solvang’s manager for the newbuilding and OCCS preparations project.
The basic design comprised units for CO2 absorption by amine-MEA, a stripper tower, and liquefaction and condensation systems, as well as CO2 storage tanks. What might look feasible on the drawing table, would pose heavy engineering issues in a shipboard environment.
«From the fall of -23 to the fall of -24, we carried out hazard analyses, detailed design of dimensions, energy balance assessments, practical machinery and supplier vetting. Among the challenges was the need for extra heat energy, which required larger boiler steam capacity. Also, we had to arrange for fresh water supply, among the many things which we submitted for class approval», Mr. Sirevåg recounts.
VLGC modifications
After a full 3D scanning of Clipper Eris, an OCCS was installed at year-end -24. This meant real-time testing could start delivering operational data. At the same time, the Hyundai HHI shipyard commenced structural preparations for OCCS on Solvang’s VLGC newbuilding project.
«The success of the pilot is a critical element in the OCCSready project on the VLGC newbuildings», Mr. Sirevåg admits.
The seven identical VLGC newbuildings will feature exhaust gas recirculation (EGR), exhaust gas cleaning (hybrid scrubber), plus the WESP (electrostatic particle filter). Together these processes prepare the exhaust gas stream for the CO2 capturing system, which requires substantial preparations of the VLGCs.
«The deck is being heavily reinforced to carry gas tanks weighing up to 3000 tons at fore and to carry OCCS equipment at the aft. The whole bridge is being lifted by one accommodation deck to secure the necessary sightline above the projected CO2 tanks. The steam generation plant and auxiliary engines are dimensioned for a future OCCS retrofit», Mr. Sirevåg explains.
Future-proof design
With the OCCS project, Solvang has anticipated that IMO and other regulators will make CO2 emissions increasingly costly for shipping, which is the current trend. In the unlikely case that CCS operation will not be preferred, the extra CO2 tanks can be used for other fuel or cargo, such as LPG or ammonia. Which proofs the design for several future regulation scenarios.
«We venture as far as we responsibly can in arranging for a full OCCS retrofit without actually performing it», Mr. Sirevåg comments.
The optimal scenario for 2026, when the first two VLGC newbuildings are scheduled to leave the shipyard, is to have all data and preparations ready for an immediate OCCS retrofit.
«We realize this is very optimistic, also because retrofit engineering and procurement takes time. But we hope that the commercial and regulatory circumstances will contribute to speed up the OCCS installation on board our newbuilding VLGCs», Mr. Sirevåg concludes.
«The sheer possibility of onboard carbon capture was unthinkable five-six years ago, but now we run the technology on board Clipper Eris. Given the adoption of GHG regulations as expected, OCCS is short to medium term one of the most realistic strategies for cost-effective fuel in deep-sea shipping», fleet director Tor Øyvind Ask says.
Fact: The carbon capture process
Solvang’s carbon capture starts in the absorption tower, where the exhaust gas from the scrubber enters near the bottom to flow upwards, while an amine-MEA solvent enters at the top to circulate counter-current to the exhaust stream. In the absorber package section the exhaust and solvent create an exothermic reaction which absorbs the CO2, while heating up the exhaust gas stream.
The de-carbonized exhaust gas flows to a separate washing section, then passes through a separator to minimize droplet entrainment and carry-over before being released. The absorbed CO2 is being transferred to the stripper tower, where the enriched solvent gets heated to the point of releasing the CO2. The following drying and liquefaction involves several stages, a.o. the drying filtration, pre-cooling, compression and so-called subcooling of CO2. Finally, the pressurized CO2 is refrigerated by use of ammonia, into full condensation and liquefaction suitable for transfer to tank storage at the fore deck.
Fact: OCCS-ready newbuilding panamax vlgcs
In 2023, Solvang ordered seven new 88,000 cbm Panamax VLGCs. The first two newbuildings are already under construction at Hyundai HHI shipyard in Ulsan, South Korea. The vessels feature the latest hull, shaft and propeller optimizations, as well as improved coating, exhaust gas recirculation, and exhaust gas cleaning (hybrid scrubber).
The deck is reinforced to carry gas up to 3000 tons at fore and OCCS equipment at the aft. The bridge is being lifted by one accommodation deck to secure sightline above the projected CO2 tanks at fore.
The first VLGCs are scheduled for delivery in 2026, the last in 2027.
