As a home-grown, cleaner-burning and renewable alternative to straight petroleum diesel fuel for construction equipment, biodiesel has come of age.
Made from specially processed vegetable oils or animal fats, it can be blended with regular diesel and used without major engine modifications. It offers performance similar to diesel and is available in all 50 states.
Biodiesel is proven to perform similarly to diesel in millions of road miles in virtually all types of car and truck diesel engines, and in countless off-road miles and marine hours, according to the National Biodiesel Board, an industry trade association.
In Europe, biodiesel is much more popular than here. Although distribution channels in the United States are limited, biodiesel is being produced by more than 145 plants throughout the country. In addition, more than 90 plants are under construction, reports Amber Thurlo Pearson of the National Biodiesel Board.
Increasing supplies
But is this fuel right for you? Keep in mind that raw vegetable oil cannot meet biodiesel fuel specifications and is not a legal motor fuel. Biodiesel is made from vegetable oil, animal fat or grease in a process called transesterification that converts it to methyl esters — the biodiesel — and glycerin, used to make soaps and other products.
Most of the biodiesel in the U.S. is made from soybean oil. Other sources include canola (rapeseed), cotton seed, sunflower seed, beef tallow and waste cooking oil.
Typically, pure biodiesel (B100), which is nontoxic and biodegradable, is mixed with regular diesel to produce blends, such as B5 (5 percent biodiesel and 95 percent petroleum-based diesel) or B20 (20/80). To ensure proper performance, biodiesel used for fuel must comply with ASTM D6751 specifications.
In the U.S., production of pure biodiesel tripled from 25 million gallons in 2004 to 75 million gallons the next year. Between 2005 and 2006, production tripled again to between 225 and 250 million gallons. The National Biodiesel Board projects that production this year will total about 300 to 350 million gallons. Still, that’s a drop in the bucket compared to the 58 billion gallons of all diesel fuel consumed in 2005.
While prices vary from one area to another, biodiesel generally costs a little more than regular diesel. However, various states have adopted tax incentives to help make biodiesel more competitive.
Biodiesel benefits
Biodiesel offers a number of advantages, say proponents. It contains no sulfur or aromatics and can be used in existing engines and fuel injection systems without modifications. It can reduce emission of unburned hydrocarbons, carbon monoxide, carbon dioxide and particulates. Also, the addition of biodiesel, even in small quantities, can improve the lubrication of critical components, such as fuel pumps and injectors.
The use of biodiesel in existing diesel engines does not necessarily void parts and materials workmanship warranties of any major U.S. engine manufacturer, Pearson notes. Most engine manufacturers support use of at least B5 biodiesel that complies with the ASTM D6751 specification.
John Deere, for example, approved B5 for general use in 2001. Some engine makers include blends up to B20 or higher in their warranty statements. This year, Cummins approved B20 for use in five of its 2002 and later emissions-compliant engine models, and Perkins Engines will release various models of B20-compliant Tier 3 engines in 2007.
Case Construction Equipment upgraded approval of biodiesel in its Case-New Holland mechanically fuel injected engines from B5 to B20 last year. The company continues to push toward higher biodiesel blends that can be used with future low-emissions-compliant engines, reports Rick Hall, vice president of product development. “We’re conducting field tests around the world to see what needs to be done to make our engines compatible with B100,” he says.
Use with care
Currently, experts advise caution as the level of biodiesel blends increases above B20. In fact, a 2005 report from the National Biodiesel Board states, “Blends higher than B20 cannot be considered a direct replacement for petroleum diesel fuel and may require significant additional precautions, handling and maintenance considerations as well as potential fuel system and engine modification.
“Problems specifically caused by any fuel, including biodiesel or biodiesel blends, are not considered manufacturing defects and generally will not be covered by any engine or fuel injection equipment manufacturer’s warranty.” Among possible concerns:
Affinity for water. Biodiesel carries water in suspension, and that can cause rust to form in the engine and components, like fuel pumps and injectors. “Follow the manufacturer’s service schedule, especially draining the water separator regularly as recommended,” Hall advises.
Cold-weather properties. As with No. 2 diesel, biodiesel will gel in very cold temperatures. While gelling won’t damage the engine, it can impede or prevent fuel from flowing, making engines difficult to start. “Gelling will plug the fuel filters and will require more frequent changing in cold weather,” Hall says.
Typically, B100 made from soybean oil starts to gel around 32 degrees F, or even higher. However, the cold-flow properties of a B20 blend are similar to those of straight petroleum diesel, and the cloud point of B20 is 3 to 10 degrees F, higher than No. 2 diesel, according to figures from the National Biodiesel Board. Blends of B5 and lower have little if any impact on cold-flow properties.
Cleaning effect. Over time, deposits form in fuel storage systems, machine fuel lines, tanks and delivery systems. Biodiesel acts as a cleaning agent, dissolving these sediments. The higher the blend, the more the cleansing effect. “This may require two or three additional filter changes when first using the fuel,” Pearson says. “We suggest fuel filter changes as a precaution due to the cleaning effect of B20 and higher blends.”
Limited experience with blends higher than B20 reveals that any sediment present is brought up quickly and clogs filters immediately, starving the engine of fuel.
Materials compatibility. Higher biodiesel blends can damage fuel hoses and seals made of certain types of elastomers and rubber compounds. However, as Hall points out, in most of today’s construction equipment these materials have been upgraded with improved elastomers or replaced with plastic compounds. “These materials are resistant to attack by biodiesel,” he says.
Shelf life. Biodiesel in storage tends to accumulate water, which supports the growth of microorganisms that can degrade performance of the fuel and plug filters. Consequently, Hall recommends using biodiesel that has been stored for no longer than three months. The National Biodiesel Board reports that biodiesel meeting the ASTM specification can be used when stored for up to six months.
Fuel Quality. Your best bet is to buy biodiesel from a Certified Marketer in the BQ-9000 program. This seal of approval from the National Biodiesel Accreditation Commission provides assurance that the fuel meets ASTM biodiesel standards and that the fuel supplier will stand behind the product.
More information about biodiesel, including location of distributors and retailers, is available from the National Biodiesel Board at www.biodiesel.org.
