Ship Freight Defra

This category uses the most recent Defra data and advice to calculate emissions from UK shipping freight. The most accurate way to measure emissions is by fuel use using the Fuel category. But often this data is not available, or, specifically for freight categories, all emissions are not due to the packages being monitored. Therefore, this category allows the user to estimate their greenhouse gas emissions based on the distance travelled and the mass of the freight being transported.

The emission factor for RoPax ferries was derived from data provided by Best Foot Forward and assumes an average HGV load factor of 13.6 tonnes, based on information from the Road Transport Statistics 2005. RoPax ferries are roll-on-roll off that carry both road vehicles and their passengers as well as having additional passenger-only capacity.

The emission factors for other types of ships presented here are derived from the information in the EMEP-CORINAIR Handbook 2003 and a report by Entec 2002. This included fuel consumption rates for engine power and speed while cruising at sea associated with different vessels. The factors refer to kgCO2 per deadweight tonne km. Deadweight tonnage is the weight of the cargo that, when added to the weight of the ship's structure and equipment, will bring the vessel down to its designated waterline. This implies the factors are based on a fully loaded vessel. Because the ship's engines are propelling the weight of the ship itself, which is a significant proportion of the overall weight of the vessel and its cargo, reducing the cargo load from the deadweight tonnage will not lead to a proportionate reduction in the amount of fuel required to move the vessel a given distance.

The emissions calculated in this category assume a fully laden ship, so if this is not the case these results will underestimate the emissions. Therefore, results from this category should be taken as a lower limit only.

How to use this category

Use the drill-down type to select the type of vessel used from the following options.

• large ropax ferry

• small tanker

• large tanker

• very large tanker

• small bulk carrier

• large bulk carrier

• very large bulk carrier

• small container vessel

• large container vessel

The distance and mass are required as profile item values.

Algorithm

CO2eEmissionFactor = CO2EF + N2OEF + CH4EF

kgCO2e = CO2eEmissionFactor * distance * mass

The result is equivalent CO₂ emissions, which includes contributions from carbon dioxide, nitrous oxide and methane emissions.