|A mine truck|
Westport Innovations and Energy Developments Limited (ENE) of Queensland, Australia, have completed the initial feasibility study (earlier post) and are now moving into the next phase of program and business planning for liquefied natural gas (LNG) powered mine trucks.
The program involves the application of Westport’s proprietary High Pressure Direct Injection (HPDI) technology to allow large mine trucks to operate on liquefied natural gas (LNG).
The two will now draw up a plan for the commercialization of the LNG mine truck retrofit product. ENE intends to present these plans to its Board of Directors by the end of the first quarter of 2006.
Australian mines operate a significant portion of the world’s mine trucks that typically haul more than 200 tonnes per truckload. These vehicles utilize high horsepower diesel engines that generate upwards of 2,000 horsepower. A single truck can consume more than one million liters (264,200 gallons US) of diesel fuel per year.
|HPDI: The diesel fuel is delivered just prior to top-dead-center, followed by the main fuel quantity of natural gas.|
High Pressure Direct Injection relies on late-cycle high-pressure injection of a gaseous fuel, such as natural gas, into the combustion chamber of a diesel engine.
Natural gas has a higher ignition temperature than diesel (1,000° C vs. 500° C) and will not easily ignite at the temperatures and pressures in the combustion chamber of a normal diesel engine. To assist with the ignition of natural gas, a small amount of diesel fuel is injected into the engine cylinder using a dual-concentric needle injector the same injector followed by the main natural gas fuel injection. The diesel fuel is delivered just prior to top-dead-center, followed by the main fuel quantity of natural gas.
The diesel fuel acts as a pilot or “liquid spark plug” which ignites rapidly the hot combustion products then igniting the natural gas.
This gives the engine the efficiency and low-speed torque advantages of compression ignition while using natural gas as the primary fuel.
With HPDI engines, approximately 95% of the diesel fuel consumed in a diesel engine is displaced with natural gas. A 150-truck fleet of mine trucks with HPDI natural gas engines could achieve emissions reductions of approximately 21,000 tonnes of oxides of nitrogen oxides, 1,000 tonnes of particulate matter, and one million tonnes of greenhouse gases over the life of the fleet.