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DIESEL ENGINES Volvo Penta was one of the first engine manufacturers to receive stage 3B and Tier 4i certificates from the U.S. Mine Safety and Health Administration (MSHA) and Canada Center for Mineral and Energy Technology (CANMET) for one of its newest Biodiesel: Burning Brighter The rising interest in mobile mine equipment fuel-switching sparked by cheaper, more widely available natural gas has pushed another viable fuel—biodiesel—out of the limelight, at least for the time being. However, biodiesel remains an alternative to petrodiesel in many mining applications, and all of the major min- ing-engine suppliers have approved biodiesel, in various blend pro- portions, for use in their equipment. In the underground mining sector, the potential harm caused by miners' exposure to diesel particulate matter (DPM) has long been a matter of concern to all involved—workers, mine opera- tors and regulators. Following the recent announcement by the World Health Organization that, based on the results of a U.S. National Cancer Institute study of miners exposed to diesel exhaust emissions, WHO now regards those emissions as car- cinogenic to humans and that level of concern has been elevat- ed exponentially. Underground mines currently can reduce worker exposure to DPM through a number of strategies: improving ventilation, using vehicles with specially sealed and pressurized cabs, improving maintenance, installing emission control devices, and using biodiesel. MSHA, for example, notes that a biodiesel blend of B35 (35% biodiesel, 65% petroleum diesel) or higher produced signif- icantly lower DPM emissions than pure petrodiesel. Although anecdotal data seems to support the claim that biodiesel-fueled underground equipment poses less of a health risk to miners, there hasn't been a conclusive study that proves this assumption. That could change in the near future, however, as focus intensifies on understanding potential benefits of biofuel. More Studies Ahead For example, the National Institute for Occupational Safety and Health recently awarded a $1.4-million grant to the University of Arizona's College of Public Health and department of mining and geological engineering for a three-year project that will compare exposure and health effects of miners using diesel versus biodiesel-fueled underground mining equipment. The study's results will have a dual purpose: Researchers want to determine the effects of biodiesel-blend fuels in the min- ing community, and also apply collected data to establish the beneficial or detrimental effects on members of the general pop- ulation who are exposed to biodiesel-blend fuels. "Exposures to diesel particulate in underground mining often exceed existing standards," said Dr. Jeff Burgess, the study's prin- cipal investigator. "Biodiesel blends are being employed to reduce these exposures, yet there is no information on whether this increases, decreases or fails to change the toxicity to miners of equipment emissions. Biodiesel usage has a wider, and older, footprint in Europe but statistics show that the North American market is growing steadi- ly. The EPA increased the amount of biodiesel products that must be blended into fuels in 2013 to 1.28 billion gallons, an increase 52 E&MJ; • NOVEMBER 2012 from the prior threshold of 1 billion gallons. The U.S. Renewable Fuel Standard required biodiesel to be included in U.S. diesel fuel markets beginning in 2010. The level was set at 800 million gallons in 2011, the first full year compliance was required, before it was increased to 1 billion gallons in 2012. After that, the EPA is required to determine how much biodiesel must be blended annually. Jon Scharingson, director of sales and marketing at Ames, Iowa, USA-based Renewable Energy Group (REG) told E&MJthat; demand for biodiesel has grown steadily over the past two years. REG is a leading producer/marketer of biodiesel products, with annual production capacity of 215 million gallons/year from six plants located throughout the central U.S. According to Scharingson, REG sold 150 million gallons in 2011, and is on track to sell significantly more in 2012; its products are delivered to customers in 49 of the 50 states. Scharingson said REG has established a market position in the underground mining sector in the U.S., largely based on the company's ability to demonstrate successful, uncomplicated use of various blends of biodiesel from B50 up to 100% in under- ground mining equipment, but also from corporate concerns about reducing worker health risks and the overall carbon foot- print at mining operations. There also has been rising interest for biodiesel, in lower blend proportions, from mining companies interested in powering various types of surface equipment. Using biodiesel in mines does pose some challenges. Like petrodiesel, certain biodiesel blends can gel in cold weather, par- ticularly biodiesel derived from non-soy feedstock. Although most mining equipment operates underground where the temperature is consistently moderate, some mines store items of equipment above ground, subjected to more extreme conditions. When nec- essary, mines can overcome gelling with methods similar to those used for cold-sensitive chemicals. Methods include moving biodiesel trains or trucks into heated buildings, installing heaters for fuel line filters, using additives that reduce cold effects, and switching between blends seasonally. Biodiesel refiners and distributors can assist users in control- ling diesel gelling problems by recommending the proper prod- uct. REG, for example, offers three biodiesel products with dif- ferent 'cloud point' ratings—cloud point refers to the temperature below which wax in diesel or biowax in biodiesels form a cloudy appearance. The presence of solidified waxes thickens the fuel and clogs fuel filters and injectors. Engine and biodiesel suppliers are unanimous in emphasizing that, regardless of the biodiesel blend level selected, end users should be sure to verify with their fuel provider that the biodiesel blend meets ASTM D6751 (U.S.) standards or an equivalent spec- ification. In the U.S., biodiesel users are strongly encouraged to purchase biodiesel blends from a BQ-9000 Certified Marketer and to source from a BQ-9000 Accredited Producer, as certified by the National Biodiesel Board. www.e-mj.com engines. Certification was awarded for its 13L Tier 4 interim model, and 'there are more to come,' according to the company. Volvo said the 350–550-hp TAD1360/ 61/62/63/64/65VE-series of diesel en- gines offer a ventilation rate that is among the lowest in the industry for the power category—at about 30 cfm/hp, it is less than one-third the traditional rate of 100 cfm/hp commonly applied to diesel engines operating in underground mines today.