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| Zero Emissions Utility Solution at the Stillwater mine |
Background
The use of hydrogen as a fuel to power underground mine vehicles has the potential to reduce significantly worker exposures to the particulates and toxic gasses generated by diesel-powered vehicles. The first step to implementation of new hydrogen technologies is to establish safe practices for handling and use of the hydrogen fuel. A prototype hydrogen-fueled mining vehicle, dubbed the Zero Emission Utility Solution (ZEUS), was outfitted with the safety systems necessary for MSHA-compliant underground deployment. ZEUS is a modified EIMCO 975 articulated utility vehicle designed for underground use. A naturally aspirated water-cooled Caterpillar 3304 diesel engine was re-engineered to burn hydrogen. Fuel storage consisted of a modular metal hydride system mounted within the trailer flatbed. Metal hydride storage of hydrogen is the same technology under widespread development for fuel-cell technology. In addition to common safety features (e.g., ROPS and FOPS protection, back-up alarm, lamps, and seat belts), the vehicle was equipped with five sensors to detect gaseous hydrogen at low levels, yet minimize false readings from other gases and compounds. The hydrogen sensors also address the possibility for failures of the fuel storage and distribution systems. Refueling presents a hazard different than that posed by the liquid fuels miners are traditionally trained to use; therefore, a protocol for safe refueling was developed for the demonstration.
ZEUS, with its unique safety systems, was successfully demonstrated at the Stillwater Mine in Nye, MT, in 2004. This was the first time a hydrogen-fueled vehicle was operated in an underground mine in the United States. The demonstration of this vehicle in a mine provided regulators and industry with the opportunity to evaluate the safety systems and controls necessary for advancing the use of hydrogen as an industrial fuel.
In addition to being highlighted in the Engineering & Mining Journal (September 2004), the demonstration was well publicized in the Montana press by the Billings Gazette (http://www.billingsgazette.com) and Stillwater County News (http://www.stillwatercountynews.com). ZEUS was also driven in three community parades in Montana towns near the mine - Fishtail, Red Lodge, and Columbus.
Potential Outcome
The introduction of hydrogen as an alternative fuel for underground mine vehicles opens new avenues for reducing miner exposure to diesel particulate matter (DPM), an identified health hazard. This research demonstrated that some vehicles in the mining fleet can be retrofitted to burn hydrogen safely. The application of hydrogen technology will likely be a last resort because it is still expensive; however, the cost of modular metal hydride storage for hydrogen will be reduced within the next 10 to 15 years. Where DPM controls are not feasible, hydrogen can be considered an alternative to diesel fuel for mine vehicles.