Fleet and CO2 Calculator

How to use the CO2 calculator

This CO2 calculator is a computer-based tool to support estimation of CO2 emissions for one of the country’s fleet components for an individual year (see section 3.3 of Ship Emissions Toolkit Guide No.1: Rapid Assessment of Ship Emissions in the National Context for more information on the different fleet components). The calculator is developed in MS Excel. It is based on data used from the Third IMO GHG Study 2014 and includes assumptions and uncertainties on operational and design speed, draught, installed power, metocean (meteorological and oceanographic) conditions, specific fuel consumption and emission factors, which vary in quantity by vessel size and type category. Results obtained using this tool should therefore be interpreted as indicative and providing guidance, rather than exact numbers for the emissions of the fleet component that is being analyzed.

The CO2 calculator uses data from the Third IMO GHG Study for the year 2012 and assumes that ships use Heavy Fuel Oil with a CO2 emissions factor of 3,114 kg CO2 /tonne fuel. All the data is shown in the tab called ‘Third GHG Study – Data 2012’.

The columns pre-filled with data from the Third IMO GHG Study (highlighted in light grey) are:

  • ‘Ship type’

  • ‘Size category’

  • Per ship average annual fuel consumption’

In order to estimate CO2 emissions for a fleet component for year X, fill in two columns(highlighted in light blue) as follows:

  • Number of ships in the fleet component: Insert the number of ships per ship type and size category that in year X were included in the fleet component you are estimating CO2 emissions for.

  • Average time spent (in %) in fleet component: Per ship type and size category, estimate for how much time in year X (in %), these ships have fallen under the fleet component in question.

  • Registered and domestic fleet, ships owned by companies registered in the country: This value will be 100% as the ships that fall under these fleet components fall under it 100% of the time.

  • Fleet servicing the country’s international transport demand and the fleet passing through the country’s territorial waters: this value will be less than 100% as the ships that fall under these fleet components serve other countries’ transport demand or pass through other countries’ territorial waters. For these two fleet components, estimate (roughly) the amount of time the ships (per ship type and size category) have spent in your territorial waters. In order to arrive at an estimate of the percentage, it might help to look at AIS-derived traffic data.