Biofuels challenge maintenance programs

EARLIER this month, more than 3,800 delegates gathered for the National Biodiesel Conference in San Antonio, Texas. That's quite an increase from the 600 who attended the first conference four years ago.

The 2007 conference provided a snapshot of just how far alternative fuels (especially biodiesel and ethanol) have come in the United States in a relatively short amount of time. Speakers pointed out that US producers made approximately 250 million gallons of biodiesel in 2006, and production this year certainly will be above that.

Ethanol, which is being blended with gasoline both as a replacement for unleaded gasoline additive MTBE (methyl tertiary-butyl ether) and as a means of reducing US petroleum imports, has even higher production levels. US producers made more than 4.7 billion gallons of ethanol (most of it corn based) in 2006. Production should top 7.5 billion gallons this year.

Convenience stores and truck stops across the country are selling increasing volumes of biofuels and biofuel blends. Growing numbers of truck fleets are opting to run biodiesel blends at least part of the time. In addition, some elected officials are considering a federal mandate for biodiesel.

All of this means that tank fleet maintenance managers, especially those working with petroleum haulers, probably will have to deal with biofuels at some point in the future. Most likely, it's going to happen sooner, rather than later.

Biofuels can impact vehicle maintenance in a number of ways, and maintenance managers must be prepared. Biodiesel will have the broadest impact on maintenance operations because it could be both fuel and cargo for tank truck fleets.

From the truck fuel side, biodiesel quality is probably the biggest issue. High levels of residual glycerin in off-spec fuel can plug fuel filters. Bacterial growth also can bring plugged filters.

Higher-percentage biodiesel blends pose a greater risk of gelling in cold weather. Mechanics must take extra care to ensure that fuel system heaters on tractors are fully operational. Tank trailers used to transport high-percentage blends or pure biodiesel (B100) must be insulated and have an operational in-transit heat system.

Biodiesel can damage some seal, gasket, and hose materials, so care must be taken in selecting these items. Speaking at the 2006 NTTC Cargo Tank Maintenance meeting, Kip Hart of Hart Industries cautioned that B100 permeates quickly through standard-grade fuel hoses built with low-medium ACN polymers.

On the plus side, biodiesel can improve the lubricity of ultra low sulfur diesel, which should reduce engine component wear. At the same time, recent studies have suggested that biodiesel might create slightly higher particulate emission levels. Researchers are still looking at what this means for particulate trap performance on the 2007 engines.

Ethanol poses the biggest challenge for tank trailer mechanics, since it is just an automotive fuel. Ethanol in various blend percentages can aggressively attack certain materials. Hart pointed out that lower percentage blends (E15, for instance) could degrade nitrile rubber hoses, seals, and gaskets. Elastomer seals on discharge valves are damaged by ethanol.

Underwriters Laboratories Inc (UL) has suspended authorization to use its markings on fuel dispensing components when gasoline blends with greater than 15% ethanol are handled. UL said high concentrations of ethanol and other alcohols make the fuel very corrosive. It's important to keep a close watch on the product handling components on petroleum cargo tanks.

Sight glasses are among the tank components affected by ethanol. Fleets report discoloration of some sight-glass materials.

All of this just makes life more and more interesting for the tank fleet maintenance managers.

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