Analysis of Class 8 hybrid-electric truck technologies using diesel, LNG, electricity, and hydrogen, as the fuel for various applications

Class 8 trucks using various powertrains and alternative fuel options have been analysed to determine their fuel economy, greenhouse gas emissions, and economic attractiveness at the present time (2013) and in the future. This was done by modelling the vehicles and simulating their operation on day, short haul, and long haul driving cycles. The economic attractive was determined by calculating the differential vehicle cost of each powertrain option and the corresponding breakeven alternative fuel price needed to recover the additional cost in a specified payback period with a fixed discount rate. The baseline vehicle was a diesel engine truck of the same weight and road load using $4/gallon diesel fuel. The use of some of the powertrains resulted in an energy saving and others resulted in higher energy consumption, but compared to the conventional Class 8 diesel trucks, conventional LNG-CI trucks, LNG-SI and LNG-CI hybrids, battery electric trucks, and fuel cell trucks can reduce CO2 emission by 24-39% over the day drive cycle and 12-29% over the short haul and the long haul drive cycles. The breakeven fuel price was calculated for all the powertrain/fuel options. The economic results indicate that at “today's” differential vehicle costs, none of the alternative powertrains/fuels are economically attractive except for the LNG-CI engine in the long-haul application (VMT=150,000 miles) for which the DGE cost is $2.98/DGE and the LNG cost is $1.70/LNG gallon. If the differential costs of the alternative powertrains are reduced by ½, their economics is improved markedly. In the case of LNG-CI engine, the breakeven fuel costs are $3.42/GDE, $1.96/LNG gallon for the long haul applications (VMT= 150,000 miles) with payback periods of 2-3 years. This makes LNG cost competitive at 2013 prices of diesel fuel and LNG. The fuel cell powered truck is also nearly cost competitive at VMT= 150,000 miles, but this requires a fuel cell cost of less than $25/kW. Hybridizing is not attractive except for the conventional diesel vehicle operating on the day cycle (some stop and go operation) for which the breakeven diesel price is about $2/gallon at ½ today's differential vehicle costs. The regulated exhaust emissions from the LNG-CI engines will meet the same standards (EPA 2010) as the new diesel engines and use the same exhaust emission technology.