The four contenders at a glance
| Fuel | GHG benefit | Readiness today |
|---|---|---|
| Biofuel blends (B24-B100) | Up to ~20-90% well-to-wake | Available now, drop-in |
| LNG | ~20-25% CO₂ (less after methane slip) | Established, needs LNG ship |
| Methanol | High if green/bio-methanol | Emerging, growing orderbook |
| Ammonia | Zero-carbon at point of use | Early trials only |
Biofuel blends
Biofuel blends mix FAME (fatty-acid methyl ester) into conventional fuel — B24 is 24% bio, up to B100 pure. The appeal is that they are drop-in: no engine change, no new tank, and certified sustainable biofuel counts as low- or zero-carbon under EU rules. The trade-offs are cost, potential oxidation stability and cold-flow issues at high blends, and feedstock availability. This is the alternative most buyers can actually use today.
LNG
LNG eliminates sulphur and particulates and cuts CO₂ by roughly a fifth to a quarter. It needs a gas-capable engine and cryogenic tanks, so it is a newbuilding or major-conversion decision, not a fuel you switch to overnight. Methane slip — unburnt methane, a potent greenhouse gas — reduces the well-to-wake benefit and is a live regulatory topic. Bunkering infrastructure is real and growing at the major hubs.
Methanol
Methanol is liquid at ambient conditions, so it is easier to handle and bunker than gas fuels, and a large methanol-capable newbuilding orderbook is coming. Its climate benefit depends entirely on how it is made: fossil (grey) methanol offers little, while bio- or e-methanol can be near zero-carbon. Energy density is lower than fuel oil, so more tank volume is needed. Today it is emerging, not mainstream.
Ammonia
Ammonia carries no carbon, so it burns without CO₂ — the reason it is seen as a long-term zero-carbon candidate. But it is toxic, has combustion and slip challenges, and needs engines and bunkering that are only now being trialled. It is the furthest from routine commercial supply of the four.
How to think about the choice
Match the fuel to the timeframe. For a compliance need today, biofuel blends (and LNG where the ship supports it) are the workable options — as the actual sales data confirms. Methanol and ammonia are strategic bets for newbuildings this decade. Across all of them, the direction of travel is set by IMO and EU carbon rules. Seven Ocean can advise on what is genuinely available, and documentable, at each port you call.
Biofuel blends are the practical drop-in option — no engine change and they count under EU rules. LNG is available if the ship is gas-capable. Methanol and ammonia are still emerging. It cuts CO2 by roughly 20-25% and removes sulphur, but methane slip — unburnt methane escaping the engine — reduces the net greenhouse benefit and is increasingly regulated. Not in routine commercial supply. It is zero-carbon at the point of use and a strong long-term candidate, but it is toxic and its engines and bunkering are still in trials. How it is produced. Fossil (grey) methanol offers little GHG saving; bio-methanol and e-methanol can be near zero-carbon.Frequently Asked Questions
Which marine fuel alternative can I use today?
Does LNG actually reduce emissions?
Is ammonia a bunker fuel yet?
What decides methanol's climate benefit?