Rail transport costs more than pipeline transport. Rail is also less safe and emits more greenhouse gases, two factors which could trigger future cost-increasing regulations. Another uncertainty is that Canadian crude competes against other commodities, including coal, ore and grain for space on the rails, which drives up prices. So if Energy East is built, Albertan crude becomes more attractive. Depending on the origin and destination of crudes, the differential between North American rail and pipeline transport is typically between $5 and $15 per barrel, which can be a makeor-break spread when oil prices are low. Tanker transport costs are still lower than pipelines. Therefore, even if Energy East is built, imported overseas crudes will always have a built-in cost advantage. So-called Very Large Crude Carriers (VLCCs) and Ultra Large Crude Carriers (ULCCs)—carrying up to two million barrels—are still the most economical method to deliver crude oil to Eastern refineries. This fact is highlighted by the economics of shipping diluted bitumen, which requires 30 percent diluent in the pipeline to move it. Diluent would likely be sold at a discount in the east compared to the west and Energy East doesn’t include plans for a return pipeline to recycle it.