An evaluation of the climate effect of selected oil spill response technologies based on their aerial emissions

Oil spill response (OSR) techniques are traditionally evaluated based on their ability to remove oil from the environment and to reduce the environmental consequences of the released oil. The objective of this study was to quantify the climate effect of different OSR techniques so this can be included in the evaluation of the different techniques. The climate effect based on aerial emissions from OSR operations during a four-day subsea blow-out of 4000 m³/day was quantified. This was done using data from the oil spill model OSCAR simulating fate of the oil, OSR-effectiveness, hours of operation, and operational information for vessels and airplanes like fuel consumption, post operational cleaning of equipment and destruction of recovered emulsion. A comparison of the total aerial emissions showed that in-situ burning (ISB) had 9-30 times higher emissions than the other modelled OSR methods; dispersants (vessels and aerial), mechanical recovery and subsea dispersant injection. The soot created during ISB was the dominant contributor to the high climate effect of ISB. However, the climate impact represents only one of multiple contributions to the total environmental effect. In some scenarios a response method with high climate impact might be preferred due to reduced impacts on, for example, sensitive ice fauna or high densities of sea birds in a threatened area. This can be evaluated using a net environmental benefit analysis, as a part of oil spill response analysis. In practice, a combination of response options is often used to minimize environmental impacts.