Green logistics is making headway. As the logistics industry shifts gears from reporting to making deep decarbonisation cuts, the quest for more accurate and informative emissions data accelerates. Which is why alternative methodologies for calculating shipment emissions, such as modelling voyage fuel consumption, are surfacing.

In this blog, we will explore:

• Why voyage-based fuel consumption is more accurate vs. alternative emission calculation methodologies
• How to calculate shipment emissions using modelled fuel consumption
• How Lune is making this advanced methodology accessible to logistics providers

How accurate is fuel consumption modelling for calculating transport emissions?

To calculate shipment emissions, you first need to know the total greenhouse gas emissions (GHGs) emitted by a transport leg, then distribute them across the cargo load.

The most accurate way to calculate transport emissions is using primary data, i.e. by measuring the actual fuel consumed. It would receive an A+ on Lune’s data quality score.

However, this primary data generally exists in silos, making it inaccessible to logistics service providers.

Modelling this fuel consumption is the next closest thing. This methodology uses detailed data about the journey to accurately replicate how much fuel was burned for a particular voyage. This would receive an A- on Lune’s data quality score.

Primary data determines actual fuel consumption; fuel modelling mirrors fuel consumption. Both methodologies are outlined by the European Environmental Protection Agency and the International Maritime Organisation, and both arrive at a conclusion that can be used to inform critical logistics emission reductions. But one is more accessible than the other.

How Lune models voyage fuel consumption

An ocean of variables influences voyage fuel consumption. That’s why Lune models the voyage fuel consumption of a specific vessel on a specific voyage. By doing this, we can account for diversions, speed, and engine efficiency, etc., to maximise accuracy.

Other calculators may model the emissions of a generic container ship or a vessel of a specific size. However, this fails to capture granularity.

Starting with voyage stages

To model the total emissions, it helps to first break the journey down into three main stages: cruising, manoeuvring, and loading/unloading. This is because the power demanded from different engines varies dramatically between these three stages.

Fuel, which releases emissions, is burned to generate this power.

Understanding engine activity

Vessels have two types of engines: a main engine and auxiliary engines. Combining the fuel burned by both these engines throughout a voyage gives us our total emissions.

The main engine powers the movement, while the auxiliary engines power everything onboard. Whether both engines are running and how much fuel they consume impacts overall fuel consumption. However, the emissions generated by either engine can also change depending on

• How much power is required of it
• Engine fuel efficiency
• What fuel is being burned

Main engine

The main engine pushes the vessel forward; it works against the forces of drag and gravity. It is, therefore, active during the manoeuvring and cruising stages. The following factors can therefore increase the amount of fuel burned by the main engine:

• Speed (calculated using time and distance)
• Changing direction

Auxiliary engines

The auxiliary engines power energy consumption onboard the vessel. These engines are active throughout all stages of the journey, but energy demand might vary. The amount of power, and therefore fuel burned, could be influenced by:

• Electricity required onboard
• Amount of refrigerated cargo

Calculating total voyage emissions

By modelling the amount of fuel burned at different stages (per hour) of the journey by the two engine classes, we can calculate the total fuel consumed on a given voyage.

Knowing the total fuel consumed and the type of fuel allows us to use a fuel emission factor to calculate voyage emissions. Provided by the International Council on Clean Transportation, these emission factors are standardised values giving tCO2e produced from one tonne of fuel burned.

The final step is to distribute total emissions across shipments. Here, we look at the individual shipment load as a subset of the vessel's TEU capacity. This means we allocate emissions proportionally.

Calculating shipment emissions using voyage-based fuel modelling with Lune

Fuel modelling overcomes the inaccessibility of primary data to provide more precise shipment calculations, which are required to inform effective emissions reductions. However, this methodology is complex, constructing its own barriers – until now.

At Lune, we’re on a mission to make every product or service climate positive by default. To do this, we need to make actionable emissions data accessible. That is why Lune’s customers do not need to provide any new information to calculate shipment emissions with greater precision.

Instead, freight forwarders, TMSs, and logistics companies simply need to provide the vessel IMO, load, and origin and destination. Lune’s emissions intelligence (EI) does the rest. Using just this information, EI can determine speed by tracking duration and distance travelled, identify the power of that vessel's main engine, and more to achieve greater precision.

Embedded into platforms, their customers then get the emissions data they need for voluntary reporting, compliance, and emissions reductions. Net zero can’t wait.

To learn more about Lune’s voyage-based methodology for calculating shipment emissions, download our infographic.