CO2 Computation Methodology

Need to understand how our CO2 API works ? Here are all the details
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Co2 emissions API

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Sinay  API provides an estimation of the CO2e emitted on a specific journey from  port A to  port B, using a specific vessel. The results are given in Tons of CO2e per container.

To fit more use cases, 2 estimation results based on 2 different methods are provided (named thereafter Tradelanes and Vessel Model). (Sinay, 2022) More information on these methods is available in this help center article.

Both methods use an estimation of the distance between the 2 specified ports. Both methods use  the same distance estimation model, which has been developed internally.

Distance estimation


The distance estimation considers that the voyage does not contain intermediate stops (  Computing CO2e for each intermediate voyage can be done manually by specifying every port manually if needed).

Voyage distance is computed from the departure port to the waiting zone of the arrival port.

The calculations of this API are optimized for cargo and tanker vessel types. Both our routes and models are sub-optimized for ferries, fishing vessels…


Route DB

Sinay owns a route database that has been built while collecting and aggregating AIS data over several years. This data is used to identify usual routes used by vessels between ports.

Routes are connected in the system, meaning that a possible route can be drawn and used when data is missing (historical data on a specific departure/arrival combination for example.)

Using the route system to estimate distance

When a distance computation is requested: the route database is searched to retrieve  the shortest route connecting the departure and arrival.

Using the route system to estimate average speed and voyage duration

The duration of a voyage per vessel type is estimated using a machine learning model has been trained over the same AIS data. The model takes into account both route characteristics and vessel characteristics (for example dimensions).

Tradelanes Method

This methods consists in applying the following formula :

CO2(e,TEU) = distance * EF(CO2,TEU)

Where distance is in nautical miles, and the emission factors are given by (Smart Freight Centre, 2019) in Table 46.

For this method we give both WTT, TTW and WTW.

Vessel model Method

Default values

We consider the following assumptions as true :

  • The vessel is using HFO fuel only – When the constant values depend on the fuel, we consistently chose HFO
  • Engine type is SSD
  • Engine was built in the years 1984-2000
  • Ship load is 80% 

CO2 emission estimation

Total CO2e

For this method, we use the fuel-based emission estimation method (International Maritime Organization, 2020).

CO2(e) = C(f(co2)) * FC

Where  is the conversion factor of the fuel. We take the value declared in the (Smart Freight Centre, 2019) table 31.

And FC is the estimated Fuel Consumption of the ship over the voyage.


The CO2e is only useful if given by TEU. The conversion is given by applying this formula : 

CO2(e,TEU) = CO2(e) / Number of TEU on the vessel

The number of TEU by vessel is estimated by using the generic category of the vessel using its dimensions (ULCV, New Panamax, Post-Panamax, Panamax, Feeder…), to retrieve the estimated maximum capacity of the vessel. We then apply a 70% cargo loading factor, as recommended in the CCWG methodology

Fuel consumption estimation

The fuel consumption of the vessel over the voyage is estimated using the following formula.


Where SFOC is the Specific fuel consumption loaded. T is the voyage duration estimated with our ML model (see Using the route system to estimate average speed and voyage duration. And PB is the brake power of the vessel over that voyage).

Specific Fuel consumption

Specific fuel consumption loaded is given by the following formula from (International Maritime Organization, 2020), section B.2:

SFOC(LOAD) = SFOC(baseline)*(0.455*LOAD²-0.71*LOAD+128)

Where SFC is the baseline of the specific fuel consumption listed in (International Maritime Organization, 2020) Table 4, and load is 70% as recommended.

Power estimation

The Brake power (necessary power to propel the vessel over the voyage) is computed using the formulas defined in (Rakke, 2016) and (Mennen)

To summarize the method : we modelize the vessel resistance to hull, water and air, based on the vessel dimension (sourced from the AIS data) and a set of parameters including : water density, kinematic viscosity…


Clean Cargo Working Group. 2015. Carbon emissions methodology. 2015.

International Maritime Organization. 2020. Fourth IMO Greenhouse Gas study. 2020.


Rakke, Stian Glomvik. 2016. Ship emission calculation from AIS. s.l. : Norwegian University of Science and Technology, 2016.

Sinay. 2022. What is the difference between the Sinay and Tradelanes methods of calculation in the CO2 API. [Online] 2022.

Smart Freight Centre. 2019. Global Logistics Emissions Council Framework for Logistics Emissions Accounting and reporting v2.0. 2019.