As the economical, environmental and ethical costs associated with petroleum increase, so does the desire to find alternative fuels from renewable resources that are domestically produced. Today, it seems, biodiesel is all the rave.

It is derived from the natural oils of many sources; the most popular feedstock in the United States is soybeans, while Europeans rely on rapeseed. Biodiesel is produced by removing the glycerin from the oil, and it can be used in any concentration with petroleum-based diesel with little modification in most new engines.

Many truck stops have begun marketing biodiesel, and fleets of city buses are powered by it. It is being utilized by many industries including salt mining, aggregates and agriculture. It gets close to the same gas mileage with the proper blend ratio and costs slightly less than petroleum diesel, says Eric Ziph.

Many Benefits

Ziph works for Sapp Bros Petroleum, a petroleum wholesaler in Omaha, Neb., that also blends and sells biodiesel derived from soybeans. On July 9, Ziph was selling straight diesel for $2.89 (before taxes) per gallon. A 20% blend of biodiesel, B20 sold for $2.84 per gallon. One transport load of biodiesel is 7,500 gallons and reaps a savings of $255. Certain tax incentives also are available.

Along with the potential cost savings, there are other reasons to utilize biodiesel blends. Some even argue that it's better for the engine because of the chemical composition. For instance, biodiesel acts as a solvent and actually cleans the fuel lines of the machine as it burns. Also, a small percentage of biodiesel greatly increases the lubricity of the fuel. Ziph says this is particularly important as industry moves to low-sulphur diesel, which is much drier.

There also are the obvious environmental benefits. Ziph says that B20, compared to traditional diesel, results in 20% less unburned hydrocarbons, 12% less carbon monoxide and 12% less particulate matter. The trade-off is a 2% increase in nitrogen oxides.

“If you were burning straight B100, you could put your face over the exhaust and breathe whatever's coming out of the stack (not that you should),” Ziph says. “It smells like french fries or Kentucky Fried Chicken.”

Also, biodiesel is derived from renewable resources, whereas petroleum is increasingly difficult to come by. “As long as we've got rain and sunshine, you can always grow a new batch of biodiesel,” Ziph says.

The ethical arguments that support biodiesel are obvious, says Tim Stalp, who owns aggregates and ready-mixed concrete operations in Omaha that utilize Sapp Bros' biodiesel. “You take a home-grown product that we are building here instead of buying oil from someone who might be buying guns to go to war against us,” Stalp adds. “We have an environment to think about, but we have an even bigger picture than that because a lot of people that we buy oil from definitely aren't even friendly to us.”

Minor Drawbacks

Still, there are some drawbacks. It has been reported that fuel-filter plugging is an issue when making the initial crossover. Biodiesel's solvency, which can clean out fuel lines also can clog as buildup breaks free. The solvency of biodiesel also can degrade the glue binding paper fuel filters. This has Cummins recommending special fuel filters with StrataPore fuel-filter media. It also is recommended that the first two change intervals are cut in half to help prevent clogging.

Older engines might not respond as well as newer engines. According to Louis Wenzler, Cummins on-highway market communication director, the O-rings, gaskets and seals in older fuel systems could suffer. Biodiesel degrades certain types of rubber including natural rubber, nitrile and butyl rubber.

Volvo recommends Viton as a biodiesel-resistent material. Also, to avoid deposit formation, components made from copper, bronze, brass, tin, lead and zinc should not come into contact with the fuel.

Cummins does not recommend using blends higher than B5 in engines built before 2002, Wenzler says. Cummins engines manufactured after 2002, however, can run on fuel with up to 20% biodiesel, B20.

B20 is the most widely accepted blend. And although most engines will run on B100, most OEMs would discourage it.

Volvo says that biodiesel has lower calorific value and can create an 8% power decrease when operating with B100. As a result, fuel consumption would be 8% higher to compensate. With B20, however, there seemingly is no compromise.

Storage and Treatment

The shelf life of biodiesel is another drawback. All biodiesel should be used within six months of its manufacture. Avoid storing equipment with biodiesel for longer than three months. Wenzler says it has a lower oxidation stability compared to petroleum diesel. In other words, it starts breaking down just like the bottle of Crisco that sits in the cabinet too long. B100 begins to gel at 40° F, he adds, although this is less of an issue with smaller ratios of biodiesel. Additives are available to increase flowability.

Biodiesel also has an affinity for water. If water enters the fuel system, metal components can form deposits, potentially leading to engine failure. Stalp says he routinely relies on an additive that removes moisture similar to the way Heet removes water from gasoline. The additive also addresses biological growth that is common in low-sulphur diesel. “We call it shocking the tanks,” Stalp says.

Most water contamination is the result of improper storage. Wenzler says if an in-ground storage tank has a leak, it can draw in water. Pay close attention to the storage of the fuel and make sure it comes from an accredited dealer that meets ASTM D6751. Also, customers are usually required by OEMs to purchase from BQ 9000-certified marketers. If substandard fuel causes a malfunction in an engine, most OEMs will not cover the damage under the warranty.

Success with Biodiesel

Despite some apprehension by engine manufacturers to move beyond certain blends, some operators are pushing the limit all the way to B100.

“We have used it up to 100% in our dredges at times,” Stalp adds. “There was a time when we actually ran 100% in our Mack gravel trucks.”

This was for nearly two months. During this time, Stalp noticed a very slight power and economy reduction. But his contract price for biodiesel was good and the company saved a bundle on fuel costs. And only one engine seemed to suffer, an 8.3-liter Cummins on a ready-mixed truck. “But that's because we were working the engine so hard,” he notes.

Stalp says he also ran equipment on B50 for about six weeks. Today, however, Stalp rarely exceeds the B20 blend, particularly on new equipment still under warranty. He says that ratio is the most advantageous and the long-term effects of the fuel still need to be determined.

“At the 20% blend, we don't notice any difference in power economy. Most guys are going to claim that they get better economy; I'm not going to claim that,” Stalp remarks. He has gone through some extra fuel filters, but that is expected. Like any new product or technology, biodiesel has created the need for specific maintenance and unique issues to resolve.

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FROM THE OEM:

• Volvo CE machines can run using Fatty Acid Methyl Ester biodiesel. Wheel loaders, excavators, haulers, graders and large compact machines above 4-liter engine capacity (and fitted with Tier-II or III engines) can use up to B20 blends made from soy. Engines below 4 liters can run on a FAME blend of B5.

• All Cummins automotive and industrial engines are compatible with B5 diesel. The on-highway models: ISX, ISM, ISL, ISC and ISB engines certified to EPA ‘02 and later emissions standards, may be used with B20 biodiesel. The same ratio may be used in the off-highway engines: QSX, QSM, QSL, QSC, QSB6.7 and QSB4.5, if certified to Tier-III standards.

• Biodiesel blends up to B5 can be used in John Deere diesel engines, provided that the B100 meets ASTM D 6751 specification. Furthermore, the petroleum-diesel portion should meet the requirements detailed in ASTM D 975 commercial standards. In addition, John Deere requires that biodiesel and its B5 blend be purchased from a BQ-9000 accredited producer or BQ-9000 certified marketer/distributor.

• The only biodiesel fuel approved by Mack Trucks for use in E-TechTM, ASETTM, MP7 (both US04 and US07 emission-compliant) and MP8 engines is Soy Methyl Ester (SME or SOME) in blends up to a B5 concentration (5% blend). ASTM standards D 6751 and D 974 must be met, and suppliers must be BQ-9000 accredited.

• All New Holland engines can operate on B5 diesel while several are approved to run biodiesel blends as high as B20. These include the larger model Super Boom skid-steer loaders, loader backhoes, crawler dozers and compact wheel loaders. Biodiesel must meet ASTM D6751.

• Caterpillar says it neither approves nor prohibits biodiesel, and engine failure attributed to fuel is not covered by warranty. ACERT Technology engine model numbers C7, C9, C11, C13, C15, C18, C27, C32, and also for Caterpillar 3114, 3116, 3126, 3176, 3196, 3208, 3306, C-9, C-10, C-12, 3406, C-15, C-16, C-18, 3456, 3408, 3412, 3500 Series, C175 Series, 3600 Series, C280 Series, CM20, CM25 and CM32 engines, should not consume biodiesel blends higher than B30. Caterpillar C0.5 through C2.2 and for C4.4 mechanical fuel injection equipped engines that meet Tier-III emissions regulations may run on B20; those meeting Tier-II regulations may run on B5. Fuel must meet the requirements that are listed in the Caterpillar specification for biodiesel and ASTM D6751.

Online Resources

• National Biodiesel Board, http://www.biodiesel.org
• Cummins' Frequently Asked Biodiesel Questions, http://www.everytime.cummins.com/every/customer/faq_biodiesel.jsp
• The National Biodiesel Accreditation Program, http://www.bq-9000.org
• American Soybean Association, http://www.soygrowers.com
• United Soybean Board, http://www.unitedsoybean.org
• Alternative Fuels Data Center, http://www.eere.energy.gov/afdc/altfuel/biodiesel.html
• Collaborative Biodiesel Tutorial, http://biodieselcommunity.org