The Fuel Line

News for Vermont's Oilheat and Propane Industry

Ethanol, CBOB and RBOB

Reformulated Blendstock for Oxygenate Blending (RBOB) and his brother, Conventional Blendstock for Oxygenate Blending (CBOB) are the two base gasoline stocks that get mixed with ethanol at the terminal racks.

Ethanol is used primarily as motor fuel and a fuel additive. It is the leading oxygenate added to gasoline in the United States. The feedstock for the US fuel ethanol industry is corn. The federal government supports the ethanol industry through subsidies given to farmers and manufacturers.

Ethanol, however, has a problem. It is highly soluble with water. This means that your single-malt scotch mixes well with club soda. This also means that fuel ethanol attracts water, making it corrosive to the steel used in pipelines and  plumbing at oil refineries. If ethanol is pushed through a pipeline, the water that it attracts will corrode the inside of the pipes. If it's mixed with gasoline at the refinery, every pipe and tank that it passes through will be subjected to higher levels of corrosion.

Ethanol needs to be mixed into gasoline at the local terminal racks, just before it's delivered. The ethanol and gasoline are splash blended as the tanker truck fills before making the final trip to the gasoline station. From this point on in the supply chain, the corrosive nature of ethanol is not a concern. The tanks and piping systems of most gasoline stations today are constructed out of fiberglass and corrosion-resistant plastics. And, a protective layer of plastic lines the insides of gasoline delivery trucks.

Source: WATP