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DIESEL ENGINES Fleet Operators Ready to Gas Up The natural-gas production boom in North America and elsewhere has flared mining- industry interest in switching mobile equipment to LNG power By Russell A. Carter, Managing Editor In the era before off-road diesel engine emissions became a point of intense focus for regulatory agencies, fuel choices for large, production-fleet mining equipment were relatively simple for mine operators— mainly, "Do you have diesel, what does it cost, and when can you deliver?" Even after the U.S. Environmental Protection Agency's early off-road diesel emissions standards and their European Union counterparts came into effect in the mid-1990s, operators' fuel concerns re- mained largely the same—quantity, availabil- ity and price. Fuel cleanliness was mostly an interesting topic of discussion in mainten- ance-shop lunchrooms and fuel sulphur con- tent wasn't an operational concern for high- horsepower mining engines until more than a decade after the adoption of the Tier 1 stan- dard in North America. Although subsequent Tier 2 standards imposed drastically lower emissions levels than Tier 1 for CO, NOX and particulate matter on off-road engines larger than 750 hp (560 kW), this class of engines was exempted from the even more stringent Tier 3 standards that were applied to less powerful diesels starting in 2006. However, Tier 4 emissions-control stan- dards for the high-horsepower off-road engines commonly used in mining changed the rules of the game significant- ly when they became effective in 2011, first as an 'interim' set of standards, fol- lowed by final standards in 2015. Engine manufacturers, who had largely been able to meet Tier 1, 2 and 3 standards by apply- ing internal engine tweaks, had to develop design strategies that would allow new diesels to meet Tier 4's extremely low emis- sions levels without creating disruptive installation, operational and cost-related issues for their OEM and end-user cus- tomers. The advanced engine technologies required for Tier 4 compliance, among other things, put a premium on fuel clean- liness and sulphur content. Dirty, contami- nated diesel fuel severely shortens the service life of injectors and other extreme- ly fine-tolerance engine components, while previously acceptable fuel sulphur content levels are detrimental to specific emis- sions-control systems and components needed for Tier 4-level control. Work on LNG-powered Cat 793, 795 and 797 trucks is in the early stages, with commercial launch expected within five years. 48 E&MJ; • NOVEMBER 2012 These developments raised the ante for mine operators who need a new haulage fleet to commission a mine, for example, or want to repower to gain the benefits offered by the latest generation of high-horsepower diesels—scenarios that now would be accompanied by the cost of buying, properly storing and filtering the ultra-low-sulphur diesel (ULSD) fuel required by Tier 4-com- pliant engines. Even in less-regulated coun- tries that don't yet enforce tight emissions standards, diesel-fuel availability and quality control pose problems for fleet operators running Tier 3 or older diesels. Fuel sulphur content in some regions can be as high as 10,000 ppm, compared with levels of about 3,000 ppm that were formerly common in industrialized nations—and 15 ppm in today's ULSD—and these high sulphur lev- els can shorten the life of certain compo- nents. Maintaining proper storage conditions may be difficult, leading to several forms of contamination. In addition, the price of diesel can fluctuate wildly from unpre- dictable events, despite the government subsidies found in many developing nations. With fuel and lube costs typically accounting for 40% or more of a large sur- face mine's annual operating budget and many other operating costs currently on a steep upward climb, mine operators every- where are anxious to find economical solu- tions for controlling fuel costs. Biodiesel is becoming a viable alternative in some appli- cations (see sidebar), but even that more environmentally friendly fuel can present availability and storage problems of its own. Suppose there was a fuel, available in abundant quantities in many global regions, that offered cost savings of 50% or more over diesel, and allowed dual-fuel operation while maintaining current engine performance levels? Too good to be true? Not at all, say a growing contingent of high- horsepower engine builders jumping on the liquefied natural gas (LNG) bandwagon. www.e-mj.com