Re: 鈥�$5.8M boats idle, await pipeline call,鈥� March 2.
There is a cynical irony to the oil-spill-response vessels awaiting the government鈥檚 pipeline expansion (formerly the Trans Mountain pipeline). The twinning of the pipeline will not transport oil but rather diluted bitumen.
There is significant chemical difference between dirty oil, heavy crude and bitumen, which is extracted from the Alberta oilsands. This has to do with the ratio of asphaltenes in the extracts. The high molecular weight, high sulphur and branched asphaltenes of bitumen require significant upgrading at considerable environmental cost to convert them to useful petroleum products other than asphalt.
To transport bitumen in pipelines, it is diluted with low-density hydro-carbons such as naphtha or condensed gaseous components to decrease the density and the viscosity of the slurry so that the bitumen can flow in a pipeline.
Should there be a spill of dilbit in the sea, the dilutant will evaporate quickly and the high-density bitumen will sink, as evidenced in the Kalamazoo River spill. Hence, slow-moving skimming vessels waiting for the pipeline expansion offer limited, if any, practical value. There is no current technology to recover dilbit from water.
Al Vaisius
Emeritus Assoc. Prof. Chemistry, UBC
Cowichan Bay
