What is the difference between the Sinay and Tradelane methods of calculation in the CO2 API?

Sinay's API for CO2 emissions provides two distinct methods of calculation.

Why offer 2 methods of calculation?

The two provided methods of calculation serve different purposes and can help different types of users.

While the Sinay estimations using the Holtrop & Mennen modelization method provides an estimation for CO2 emissions per TEU based on specific vessel and route characteristics, the Trade lanes method recommended by the Smart Freight Center's GLEC Framework provides a more detailed result segmented in Tank to Well, Well to Tank and Wheel to Well emissions using market averages.

Sinay estimation using Holtrop & Mennen Approximate Power Prediction Methodology

Sinay has developed the first method of computing CO2 emissions based on the work of Holtrop and Mennen in their Approximate Power Prediction.
This method covers how to predict a ship's resistance, propulsion factors, and estimate propeller efficiency.

Combined with AIS data and route information, Sinay is able to compute and estimate of CO2 emissions per TEU for any vessel on any journey worldwide.

Using data from AIS and our databases, we modelize the ship resistance (hull form, appendages, bulbous bow...).

1. Using our route database and models, we estimate the voyage length and the average speed over the voyage.

2. Using the ship resistance + voyage parameters, we estimate the power that the vessel engine needs to deploy to travel that voyage.

3. We estimate the amount of fuel needed to deploy that power.

4. We estimate the amount of CO2 with is emitted using that fuel amount. (CO2 emitted by the vessel over that voyage)

5. We use data from the AIS to estimate the vessel capacity.

6. We use the capacity and CO2 emitted by the vessel to estimate the ttw CO2/TEU.

Sinay estimation using Tradelanes Method - GLEC Framework

1. Locate departure and arrival port

2. See in which world zone they are (defined in GLEc Framework)

3. Select the correct tradelane factor (defined in GLEc Framework)

4. Using our route database and models, estimate the voyage length

5. Using the tradelane factor and the length, estimate the co2 emission/ TEU in ttw, wtt and wtw

More information on the Smart Freight Center's GLEC Framework for CO2 emissions calculation HERE.

What is TTW, WTT and WTW

Accounting for Fuel Emissions Fuel use is most accurately reported using mass (kg) as the unit; however, in practice liquid fuels are usually measured by volume for convenience.

In order to capture the full climate impact of fuel use, as required under the Greenhouse Gas Protocol, the GLEC Framework includes emissions from the full fuel life cycle, known as well-to-wheel (WTW) emission factors.

WTW factors are comprised of two separate sub-categories: well-to-tank (WTT) and tank-to-wheel (TTW).

Well-to-Tank (WTT) emissions consist of all processes between the source of the energy (the well) through the energy extraction, processing, storage and delivery phases up until the point of use (the tank). WTT values can vary by energy source, region, method of production and the transportation required to move the fuel to market.

Tank-to-Wheel (TTW) are the emissions from fuels combusted to power Scope 1 activities (the wheel). TTW is considered to be zero for electricity, hydrogen fuel cells and biofuels – all emissions are in the WTT stages at the point of use.

Well-to-Wheel (WTW) are emissions from the full fuel life cycle, and should be equivalent to the sum of WTT and TTW emissions.

More information (see page 17)

Why is there a difference between the two results?

The difference between the results delivered by the Sinay methodology based on the Holtrop & Mennen modelizations and the Trade lane methods can be explained by the difference in compiled data:

• The Trade lanes method of calculation uses average distance from one geographic zone to another and does not take into account specific port to port distances.

• The Trade lanes method uses average dry cargo vessel characteristics and does not take into account specific vessel data such as vessel dimensions or average speed on a specific route.

• The Trade lanes method uses average fuel consumption across all fuel types.

• The Trade lanes method is recommended by the Smart Freight Center

• The Sinay method of calculation based on Holtrop & Mennen ship modelization takes into account specific vessel characteristics for container and tanker ships (vessel dimensions, average speed on route).

• The Sinay estimation takes into account the specific port to port route of the vessel and uses the actual distance between the two points.

• The Sinay estimations use HFO as default fuel type.

Which method should you use?

• If you lack specific vessel or route information, use the Trade lanes method, which provide default data for this input.

• If you want to calculate emissions for a tanker vessel, use the Sinay Holtrop & Mennen method

• If you want to calculate emissions for a specific vessel journey, use the Sinay Holtrop & Mennen method.

Vessel IMO samples

If you do not know the IMO or MMSI of the vessels you want to calculate emissions for, feel free to use one of the following to obtain default values in the Trade lanes method.

Any questions about our methodology? Want to calculate emissions with a different fuel type or vessel characteristics? Contact the team at customersuccess@sinay.fr