New Dispersant Gel Treats Marine Oil Spills more Effectively with Less Product

Abstract

Abstract Application of chemical dispersants to marine oil spills is an important response option that yields net environmental benefits in many instances—particularly for large offshore spills. When properly applied, the dispersion process quickly dilutes the dispersed oil droplets to concentrations below toxicity thresholds and allows naturally occurring microorganisms to rapidly biodegrade the oil. Conventional chemical dispersants, however, have limitations that to some extent may reduce their effectiveness for viscous oils. ExxonMobil is developing a new dispersant with a gel-like consistency that reduces or eliminates many of the limitations of current dispersants. Wave-basin tests indicated that the new dispersant's greater viscosity and higher active ingredient content allow it to treat conventional oils with dispersant-to-oil ratios as low as 1:60 or lower (compared to 1:20 typically used for dispersants) and to disperse oils currently considered too viscous, e.g., heavy crude oils, fuel oils, or oils that become viscous in Arctic climates. The new formulation dispersed heavy California crude oils and heavy fuel oil collected after the 2002 Prestige spill significantly better than a widely stockpiled dispersant (Corexit 9500) in side-by-side tests. Responders did not attempt to use dispersants on the Prestige spill because they considered the oil too viscous. Wind-tunnel tests that simulated spraying the gel from an airplane indicate that the high viscosity of the product does not cause significant delivery issues – a simple gear pump effectively sprayed the product. In addition, the gel passed tests required by the US Environmental Protection Agency for use in the United States. The advances provided by the new dispersant may more than triple the capacity of a single plane load of dispersant, and disperse oils currently considered too viscous either because of naturally high viscosity, weathering, emulsification, or cold temperatures. This new technology represents the first major advance in dispersants in at least a decade.