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

Abstract

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 CO 2 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.

Battery Dimensioning and Life Cycle Costs Analysis for a Heavy-Duty Truck Considering the Requirements of Long-Haul Transportation

“…The determined battery capacities are significantly higher than the values of 270 kWh and 400 kWh assumed in comparable studies [12,13] due to the specified driving period and routes. The determined capacity values are used for the simulation of the transport scenarios specified in the next section and the integration of the traction battery into the truck is analyzed in Section 3.2.…”

Comparative Study of Powertrain Hybridization for Heavy-Duty Vehicles Equipped with Diesel and Gas Engines

“…The primary motivation behind this was to compare the fuel economy improvements that can be achieved by the hybridization of a diesel-based powertrain and a gas-based powertrain. It is assumed that such a powertrain modification could be relevant for those HD vehicles, whose operating schedules include a considerable share of city and suburban haulage since the major effect of HD powertrain hybridization is expected in conditions allowing for intensive use of regenerative braking, which is the most efficient tool for increasing the fuel economy of vehicles with large masses [10].The published studies (see, for example, [11][12][13][14]) have demonstrated that hybrid HD vehicles having a gross mass ranging 16 to 36 tons possess a significant fuel-saving potential in city driving conditions, especially in the case of full hybridization, which offers up to 35% fuel consumption reduction. The mild degree of hybridization is able to provide moderate fuel savings of about 10%.…”

“…The fuel economy of powertrains, which use different kinds of fuels, cannot be compared directly. One can evaluate the energy content of the consumed fuel [15], or the CO 2 emissions of compared vehicles [12,15], or the economic aspect, i.e., fuel price [12,15,16]. This work employed another approach stemming from the goal of hybridization, namely to reduce the fuel consumption relative to the baseline powertrain.…”

Technoecological analysis of energy carriers for long‐haul transportation

“…To reverse this trend, a variety of technologies have emerged in recent years, primarily driven by the development in the passenger vehicle sector (Zhao, Burke, & Zhu, ). Besides the total or partial electrification of the drivetrain using hybrid electric vehicles (HEV), battery electric vehicles (BEVs), or fuel cells electric vehicles (FCEV), substituting diesel with liquefied natural gas (LNG) promises a reduction in GHG emissions.…”