Among emerging marine propulsion concepts, onboard carbon capture, commercial sail cargo ships, autonomous electric vessels and shore power all have real sea demonstrations from 2023 to 2026. Superconducting and magnetohydrodynamic drives remain at prototype level, with no demonstration found since a Chinese MHD test in 2017.
What it is and how it works
Five frontier ideas touch propulsion-plant design without replacing the main engine outright. Onboard carbon capture (OCCS) scrubs CO2 from engine exhaust with amine solvents or calcium oxide pebbles, then liquefies and stores it for discharge ashore; its propulsion implication is a fuel penalty for heat and power plus space and stability for CO2 tanks. Sail cargo ships use primary wind propulsion, from schooner rigs to rigid wing sails, with engines as backup. Autonomous electric vessels pair batteries with pod and tunnel thrusters under remote supervision. Shore power moves hotel load to the grid at berth and pushes designs toward hybrid-electric plants and high-voltage shore connections. Superconducting motors and magnetohydrodynamic (MHD) drives have not left the prototype stage.
Why it matters now
The decisive question for a fleet planner is which concepts have real sea results. Carbon capture, sail cargo, autonomy and shore power do. Superconducting and MHD drives do not: Japan's Yamato-1 of 1991 is recognised as the first superconducting MHD propulsion ship (Preprints.org), AMSC and Northrop Grumman load-tested a 36.5 MW HTS ship propulsion motor in 2009 at less than half the size of a conventional destroyer motor, and China's defence ministry reported an MHD test at Sanya in October 2017. No 2024-2026 demonstration was found. Regulation is now moving on two of the concepts: the IMO approved an OCCS regulatory work plan at MEPC 83 in April 2025, with finalisation targeted for 2028 (IMO), and adopted the first voluntary MASS Code at MSC 111 in May 2026.
Key players and products
Carbon Ridge's centrifugal OCCS pilot on Scorpio Tankers' STI Spiga began commercial voyages in July 2025; DNV's assessment confirmed capture rates up to 98%, with more than half of recorded results between 86% and 98%. Seabound's 2024 sea trial on Sounion Trader captured CO2 at 80% and SO2 at 90% using calcium oxide pebbles. EverLoNG on the LNG carrier Seapeak Arwa reached up to 85%, and Stena Bulk's REMARCCABLE study projected a 19.7% net CO2 reduction for a 9.2% fuel penalty. In sail cargo, Neoline's 136 m ro-ro Neoliner Origin, with 3,000 m2 of sail on two masts, was delivered by RMK Marine in October 2025 and crossed the Atlantic in eight days; TOWT's schooners Anemos and Artemis completed 21 transatlantic round trips in 2025 and the company plans eight ships by 2027. Yara Birkeland, the 120 TEU autonomous ship, runs two 900 kW Azipull pods and two 700 kW tunnel thrusters on a battery of about 7 MWh at 13 knots.
Figures that matter
| Metric | Value | Source type | Source |
|---|---|---|---|
| Carbon Ridge capture on STI Spiga | peak 98%, over half of results 86-98% | verified | DNV |
| Seabound on Sounion Trader | 80% CO2, 90% SO2 | trade-press | — |
| GCMD Project CAPTURED, gross capture | about 10.7%, 5-6% energy penalty | trade-press | CleanTechnica |
| REMARCCABLE projection | 19.7% net cut, 9.2% fuel penalty | trade-press | Maritime Gateway |
| TOWT 2025 operations | 42 crossings, 68,295 nm | vendor | TOWT |
| Windcoop sail container ship | 210 TEU, 1,050 m2, EUR 28.5 m | trade-press | — |
| MASS Code mandatory | in force 1 January 2032 | regulatory | IMO via USCG |
| FuelEU shore power | from 1 January 2030, over 5,000 GT | regulatory | Maersk Mc-Kinney Moller Center |
OCCS results are not comparable across pilots. Carbon Ridge's 86-98% is a capture-unit rate under DNV assessment, whereas GCMD's full-chain Project CAPTURED captured only about 10.7% gross on VLSFO with a 5-6% energy cost, according to a critical analysis (CleanTechnica). SINTEF finds engine exhaust heat alone cannot run amine capture above about 50%, and an afterburner adds 6-9% fuel on LNG and 8-12% on diesel (SINTEF). Windcoop's binding order with RMK Marine covers a 91.3 m, 210 TEU ship with three 350 m2 wing sails, a 60% CO2 reduction target and a EUR 28.5 million budget for delivery in 2027.
Developments 2023-2026
- 2025: MEPC 83 approves the OCCS regulatory work plan in April; Carbon Ridge's pilot begins in July; Neoliner Origin is delivered in October.
- 2026: DNV confirms the 98% peak capture rate in June; the IMO adopts the voluntary MASS Code in May, effective 1 July 2026 for cargo ships with four autonomy levels, with mandatory code work from 2028, adoption in 2030 and entry into force on 1 January 2032 (US Coast Guard).
- 2030: FuelEU Maritime requires container and passenger ships over 5,000 GT moored more than two hours in TEN-T ports to use shore power, with fuel cells, batteries and onboard wind or solar as permitted alternatives (Maersk Mc-Kinney Moller Center); shore electricity is typically under 5% of a ship's energy.
Outlook
The 2028 IMO framework will decide whether captured CO2 counts for compliance, which settles the OCCS business case more than any capture rate. Shore power's design effect is more hybrid-electric plants, not different main engines. Solar-assisted propulsion could not be researched, and superconducting drives show forty years of prototypes without commercial uptake.
