LNG dual-fuel propulsion took 63% of the alternative-fuel ship orders registered in 2026 through August and 188 of the 275 orders placed in 2025, because LNG is the cheapest route through EU ETS and FuelEU Maritime. The decisive technical question is now methane slip, where high-pressure two-strokes are guaranteed at 0.2-0.28 g/kWh while independent campaigns measured 6.4% on low-pressure four-strokes.
What it is and how it works
An LNG dual-fuel ship stores liquefied natural gas in cryogenic tanks and burns the vaporised methane in an engine that keeps a diesel pilot for ignition and can fall back to fuel oil. Three engine families carry the fleet: high-pressure diesel-cycle two-strokes led by the Everllence ME-GI, low-pressure Otto-cycle two-strokes (WinGD X-DF, Everllence ME-GA) that premix gas with air, and four-stroke dual-fuel engines in the DFDE and TFDE electric plants of LNG carriers, cruise ships and ferries.
The difference that matters is methane slip, fuel that leaves the exhaust unburned. Everllence guarantees 0.2-0.28 g/kWh for the ME-GI across the load range, according to its own Everllence technical paper. WinGD reported that final shop tests of an X-DF engine with variable compression ratio cut methane emissions by about 30% and brought total slip to roughly 0.83% of gas consumption, with fuel savings of up to 5.8% in gas mode; both figures are vendor claims. Wärtsilä claims 0.9% weighted-average slip for its NextDF four-stroke technology.
Independent measurements are higher. The ICCT FUMES campaign found a real-world average slip of 6.4% from low-pressure dual-fuel four-strokes, and remote marine-station measurements in Finland published via PMC gave a median of 3.0% for low-pressure four-strokes against 0.3% for two-strokes.
Why it matters now
Slip is priced. FuelEU Maritime applies default methane-slip factors of 0.2% for high-pressure two-strokes, 1.7% for low-pressure two-strokes, 2.6% for lean-burn spark-ignited engines and 3.1% for low-pressure four-strokes and any uncertified engine, as summarised in the Marine Pollution Bulletin. The European Commission published guidelines in late 2025 allowing operators to replace the defaults with certified measured values, and the IMO adopted methane-slip measurement guidelines in resolution MEPC.402(83) in April 2025, according to ClassNK. A high-pressure engine at 0.2% versus an uncertified engine at 3.1% changes a ship's well-to-wake intensity materially, which explains the ME-GI's resurgence and WinGD's push into variable compression ratio and a high-pressure engine.
The underlying climate case rests on industry-commissioned work: the Sphera life-cycle study for SEA-LNG and SGMF puts the well-to-wake reduction for two-stroke engines at 14-23% versus VLSFO. Gasum, a supplier, argues that LNG lowers combined EU ETS and FuelEU costs in 2026; that is a supplier claim.
Key players and products
Everllence (formerly MAN Energy Solutions) and WinGD design the two-strokes; WinGD counted more than 800 X-DF engines in service and on order by December 2024, and Everllence's dual-fuel two-stroke portfolio has passed 2,000 cumulative orders. Wärtsilä supplies four-stroke dual-fuel engines, SEA-LNG is the industry coalition and Gasum is a leading European supplier of LNG and bio-LNG.
Maersk defines the demand side. After contracts for up to 22 LNG dual-fuel ships in 2024 and up to 12 in November 2025, it ordered eight 18,600 TEU LNG ships from New Times Shipbuilding in February 2026 for 2029-2030 delivery, taking its LNG orderbook to 33 vessels and omitting any mention of methanol-readiness.
Figures that matter
| Metric | Value | Source type | Source |
|---|---|---|---|
| Share of 2026 alternative-fuel orders through August | 63% | aggregator | DNV via LNG Industry |
| Alternative-fuel orders in 2025 that were LNG | 188 of 275 | aggregator | DNV |
| LNG-fuelled deliveries | 193 in 2025; 61 in H1 2026 | aggregator | DNV |
| ME-GI guaranteed methane slip | 0.2-0.28 g/kWh | vendor | Everllence |
| X-DF slip with VCR, shop test | about 0.83% of gas consumption | vendor | WinGD |
| Real-world slip, low-pressure four-strokes | 6.4% average | verified | ICCT FUMES |
| FuelEU default slip factors | 0.2% HP two-stroke; 1.7% LP two-stroke; 3.1% LP four-stroke | regulatory | Marine Pollution Bulletin |
| LNG bunkering ports and bunker vessels | 222 ports; 109 bunker vessels | trade-press | SEA-LNG |
Developments 2023-2026
- 2024: Maersk contracts up to 22 LNG dual-fuel container ships, an order analysts link to the slow scale-up of green methanol.
- Early 2025: WinGD completes final shop tests of X-DF variable compression ratio technology and later books its 100th VCR order.
- April 2025: IMO adopts MEPC.402(83) guidelines for measuring methane slip; late 2025: the European Commission issues guidance for reporting measured slip under FuelEU.
- 2026: Global LNG bunker volumes average about 770,000 m3 per month in January-May, about 13% higher year on year; bunker vessels are up from 9 to 109 and ports from 10 to 222 over the decade.
- 2025-2026: Rotterdam bio-LNG bunker sales rise from 2,775 m3 in 2024 to 17,644 m3 in 2025 and 15,260 m3 in Q1 2026 alone; Gasum's bio-LNG share of its sales climbs from 0.8% to 12.3%, and Gasum promotes FuelEU pooling in which a few bio-LNG ships generate surplus for a pool.
- February 2026: Maersk orders eight 18,600 TEU LNG dual-fuel ships, taking its LNG orderbook to 33; WinGD unveils a high-pressure dual-fuel LNG engine.
Outlook
Fleet counts conflict: Gasum cites roughly 800 LNG-capable vessels in service and about 600 on order, while SEA-LNG counts more than 1,550 in operation or on order. Bio-LNG remains well under 5% of global LNG bunkering and e-LNG is at pilot scale, so the near-term case rests on low-slip engines and blending.
