The importance of economies of scale for reductions in greenhouse gas emissions from shipping

AbstractCO2 emissions from maritime transport represent 3.3% of the world's total CO2 emissions and are forecast to increase by 150%–250% by 2050, due to increased freight volumes (Second IMO GHG study, 2009). Fulfilling anticipated climate requirements (IPCC, 2007) could require the sector to reduce emissions per freight unit by a factor of five or six. The International Maritime Organization (IMO) is currently debating technical, operational and market-based measures for reducing greenhouse gas emissions from shipping. This paper also investigates the effects of economies of scale on the direct emissions and costs of maritime transport. We compared emissions from the current fleet (2007), with what can be achieved by increasing average vessel size. The comparison is based on the 2007 levels of trade and predictions for 2050. The results show that emissions can be reduced by up to 30% at a negative abatement cost per ton of CO2 by replacing the existing fleet with larger vessels. Replacing the whole fleet might take as long as 25 years, so the reduction in emissions will be achieved gradually as the current fleet is renewed

Reductions in greenhouse gas emissions and cost by shipping at lower speeds

CO2 emissions from maritime transport represent a significant part of total global greenhouse gas (GHG) emissions. According to the International Maritime Organization (Second IMO GHG study, 2009), maritime transport emitted 1046 million tons (all tons are metric) of CO2 in 2007, representing 3.3% of the world's total CO2 emissions. The International Maritime Organization (IMO) is currently debating both technical and market-based measures for reducing greenhouse gas emissions from shipping. This paper presents investigations on the effects of speed reductions on the direct emissions and costs of maritime transport, for which the selection of ship classes was made to facilitate an aggregated representation of the world fleet. The results show that there is a substantial potential for reducing CO2 emissions in shipping. Emissions can be reduced by 19% with a negative abatement cost (cost minimization) and by 28% at a zero abatement cost. Since these emission reductions are based purely on lower speeds, they can in part be performed now.Maritime transport Speed reductions Greenhouse gas emissions