Maritime carbon footprint: why ships in operation are the blind spot of decarbonization

Maritime transport accounts for approximately 3% of global greenhouse gas emissions. A figure that may seem modest — until you remember that, without concrete action, these emissions could reach 130% of their 2008 levels by 2050. Yet the vast majority of decarbonization efforts focus on new vessels.

The problem? Today there are 110,000 ships in operation worldwide, and shipyards only produce 900 per year. Even building 100% zero-emission ships today, it would take more than 120 years to renew the global fleet. The real battle is therefore being fought on ships already in service — and it hasn't yet begun.

The problem: you can't decarbonize what you can't measure

To reduce emissions, a shipowner must first know what they emit. And that's where the problem lies. Today, the vast majority of maritime operators are navigating blind when it comes to their carbon footprint.

The reasons are multiple:

• Consumption data is scattered across paper logbooks, fuel order forms, and engine readings

• Emission factors vary by energy type (diesel, LNG, hydrogen, e-methanol…) and are rarely mastered onboard

• Regulatory obligations — CSRD, CII, European MRV — are multiplying, but the tools to address them simply don't yet exist

Result: when a shipowner wants to do their carbon assessment, they engage in a manual, lengthy, and costly process — or they simply don't do it.

80% of a vessel's footprint comes from its operation

This is the key figure: 80% of a ship's carbon footprint is generated after its launch, during its daily operation. Shipbuilding, material manufacturing, shipyards — all of that represents only 20% of the total footprint.

This observation has a direct implication: acting on existing vessels, on the way they are operated, is by far the most effective lever for decarbonizing the sector. More effective than waiting for the next generation of ships. More immediate than major international policies.

The main emission sources onboard are:

• Propulsion (main engines, fuel consumption)

• Electricity generation (generators)

• Auxiliaries (pumps, air conditioning, navigation systems)

• Port operations (shore power, maneuvering)

Identifying these sources, quantifying them, and comparing them over time: that's the work most shipowners cannot yet do easily.

How to automate a vessel's carbon assessment?

This is the challenge that BoatOn, a Bordeaux-based company specializing in maritime digitalization, took on with the support of ADEME (the French Agency for Ecological Transition). In 2025, BoatOn integrated into its BoatOn Book software the first automated carbon assessment system dedicated to ships in operation.

The logic rests on three complementary pillars:

1. Integrated CMMS — Maintenance management automatically collects technical data: types of energy used, volumes loaded, emission factors associated with each piece of equipment. No more manual re-entry.

2. Automatic logbook — Beyond meeting a regulatory requirement, the logbook continuously records navigation data: speed, heading, distance traveled, consumption, passengers or cargo transported. This data feeds directly into emission calculations.

3. The proprietary algorithms + ADEME Empreinte® database — Drawing on the official ADEME database and the GHG Protocol methodology, the system automatically models the main greenhouse gases (CO₂, CH₄, N₂O) and atmospheric pollutants (SOx, NOx, fine particles), without human intervention.

The result: an interactive dashboard, updated in real time, accessible from a computer or smartphone — even without internet connection.

What the dashboard enables in practice

A shipowner using the carbon assessment module of BoatOn Book can, in a few clicks:

• Visualize GHG emissions (scope 1) by vessel, by fleet, or by period

• Analyze energy consumption: fossil fuel, electricity, hydrogen, LNG, e-methanol…

• Track atmospheric pollutants: sulfur oxides, nitrogen oxides, fine particles

• Calculate carbon dividends — the tonnes of CO₂ avoided thanks to deployed alternatives (electric propulsion, shore power connections, etc.)

• Compare performance over time to measure the real impact of actions taken

These indicators can then be exported to meet reporting obligations (CSRD, CII) or communicated to clients and partners as tangible proof of environmental commitment.

Beyond the carbon assessment: a complete view of performance

The carbon assessment doesn't stand alone. For a shipowner to truly act, they must be able to put their environmental data in perspective with their financial and operational data. That's why BoatOn Book also offers:

• A technical dashboard: availability rate, MTBF, MTTR, breakdown frequency, average cost per intervention

• A commercial and financial dashboard: revenue by vessel, operating cost, load factor, margin per voyage

• An HR dashboard: working hours, rest hours, MLC compliance

All these indicators are fed automatically from data entered daily by crew onboard — no double entry, no Excel spreadsheet.

Common mistakes to avoid

Confusing carbon reporting with carbon action

Producing an annual PDF on emissions doesn't reduce anything. The challenge is to have real-time data to identify levers for action and measure their impact month after month.

Underestimating the necessary granularity

A global carbon assessment at fleet level doesn't allow prioritization. You need to drill down to the vessel level, or even the mission level, to identify what's really consuming.

Treating the carbon assessment as a one-off project

It's a continuous process. Emissions evolve with routes, equipment, crews. Only an automated tool allows you to track it without dedicating specific resources.

In summary: key takeaways

• Maritime transport accounts for ~3% of global GHG emissions, with a risk of +130% by 2050 without action

• 80% of a vessel's carbon footprint comes from its operation, not its construction

• The existing fleet (110,000 ships) will not be renewed for 120 years: it is on these that we must act now

• Measuring emissions in real time is the mandatory first step for any decarbonization approach

• Tools like BoatOn Book, developed with ADEME, allow this assessment to be automated without specific expertise or dedicated resources

Maritime decarbonization won't happen by waiting for the next ship. It will happen by optimizing those that are sailing today.