Rocks & mirror
Encyclopedia of Marine and Energy Technology

Annual Efficiency Ratio (AER)


“AER”, a carbon intensity metric calculated in accordance with Poseidon Principles. Similar to the “EEOI” but is an approximation of cargo carried by utilizing the vessel’s designed deadweight ( or Twenty-foot Equivalent “TEU” or passenger or gross tonnage) capacity in place of the actual cargo carried and assumes the vessel is continuously carrying cargo.  A measure of the supply of shipping capacity.  This method typically underestimates carbon intensity because ships are not always fully utilized in terms of capacity and many ships ( tankers, bulkers ) operate on ballast legs for several voyages a year without cargo onboard. It is a carbon intensity indicator “CII”.     

Where Ci is the carbon emissions for a voyage i is computed using the fuel consumption and carbon factor for each type of fuel, dwt is the design deadweight of the vessel, and Di is the distance travelled on a voyage i.