Diesel prices will eventually rise as the economy fully recovers. Couple that with the ever-growing movement to transition away from petroleum-based fuels -- stemming from the desire to achieve energy independence and as a result of the oil spills in the U.S. and China -- and the spotlight is clearly placed on alternative fuels. Currently, biodiesel leads the way in the construction industry.
Yet, the industry faces a major challenge due to recent expiration of the biodiesel tax credit. "The catastrophe in the Gulf is crushingly sad and infuriating to continue to watch month after month," fumes Joe Jobe, CEO, National Biodiesel Board. "But what is almost as frustrating is to hear members of Congress talk about the need for more clean energy sources like wind, solar and advanced biofuels. Meanwhile, their inaction is suffocating the only biofuel that has achieved commercial success in America -- biodiesel."
Biodiesel is used in blends anywhere from B5 (5%) to B100 (100%). OEMs typically determine the most appropriate level of blending to ensure trouble-free performance of their equipment.
"Our engines are approved for B20 now without any additives," says Joe Mastanduno, product marketing manager, engine/drivetrain, John Deere Construction and Forestry Division. "You can use B20 in our present engines, Tier III engines and all of the old engines with no problem. Above B20, you have to start with additives and some preventive actions."
According to Hind Abi-Akar, technical expert, fluids engineering, Caterpillar, "B20 blends are acceptable in the majority of Caterpillar engines. Up to B5 is acceptable in some Tier II and older small engines."
Technical issues regarding increased concentrations of biofuel can be categorized into aftertreatment and fuel system concerns. "Use of blends higher than B20 in aftertreatment-equipped engines can increase the rate of ash deposit in particulate filters," explains Abi-Akar. "Additionally, the lower oxidation stability of biodiesel and the potential contaminants in this fuel (alkali and alkaline metals) may cause or increase common rail fuel system deposits, leading to complaints of low power or black smoke."
The safe ambient temperature operating range can also be affected by the blend level. "Higher blends may have higher cold temperature operability risk (higher cloud point) and may also impact engine oil drain intervals," says Abi-Akar. (Caterpillar requires engine oil testing when higher biodiesel blends are used.)
But there are several successful applications of very high blend levels. "Higher blends of biodiesel are currently being used in certain applications and will continue to be used in the future," says Jobe. "For example, high blends such as B100 are broadly used in underground mining equipment, where reducing the toxicity of exhaust emissions is important to the health and safety of workers or to meet regulatory requirements. This is also the case in warehousing and other indoor applications.
"There are also a number of fleets and individuals who use high blends to maximize their petroleum displacement," he adds.
"Use of B100 does have an increased cost and additional handling and operational effort associated with it," Jobe admits. "For example, B100 does freeze at a higher temperature than No. 2 diesel fuel, so that needs to be taken into account. And B100 can affect some hoses and gaskets -- particularly those in systems before the introduction of 500-ppm sulfur petrodiesel fuel. Therefore, blends up to B20 are expected to continue to be the most popular and make up the majority of usage, as those blends are drop-in replacement fuels that provide the largest benefits for the least cost."
"Biodiesel has lower BTU (thermal energy) than diesel due to the chemical nature of the fuel," says Abi-Akar. "At lower blends and up to B20, customers may not notice a power difference compared to diesel fuel. The higher the biodiesel fuel blend, the more the customer may notice the difference. At B100, a loss of 7% to 9% in power may be noticed."