Advanced engine technologies will play a central role in achieving future greenhouse gas (GHG) emissions targets for light-duty vehicles. However, these technologies will place greater emphasis on optimizing the engine and fuel as a synergistic system, since many technologies will require higher octane gasolines to realize their full social and environmental benefits. The most extreme example of a synergistic engine-fuel system is the Octane-on-Demand concept. This technology platform makes use of an oil-derived fuel at low and intermediate loads where the octane requirement of the engine is comparatively low, while a second high octane fuel is introduced at higher loads to suppress knock. This paper presents the first comprehensive study of vehicle fuel economy and well-to-wheel GHG emissions for the Octane-on-Demand concept with respect to a regular grade E10 gasoline (RON 93) and a high octane E30 gasoline (RON 101). Experimental fuel consumption maps are first used to evaluate the drive cycle fuel economy and GHG emissions for a light-duty vehicle equipped with two alternative powertrains. The upstream GHG emissions arising from the production of the fuels are then quantified, with consequent uncertainties assessed using Monte Carlo analysis based on probability distribution functions for critical input parameters. The results demonstrate that the Octane-on-Demand concept used in conjunction with either methanol or ethanol generally provides comparable well-to-wheel GHG emissions to the high octane E30 gasoline, with up to a 10% improvement in the vehicle fuel economy. The use of a non-traditional engine calibration strategy that maximizes the trade-off between thermal efficiency and fuel energy density also enables the amount of high octane fuel required to suppress knock to be reduced significantly. This increases the distance that the vehicle can be driven before the secondary tank requires refueling by a considerable margin, but comes at the expense of marginally higher well-to-wheel GHG emissions than could otherwise be achieved. These findings are shown to be largely insensitive to uncertainties in the upstream fuel production GHG emissions, with the exception of the land use change (LUC) for bioethanol. Overall, this study has implications for the design of engine-fuel systems for future light-duty vehicles.

先进的发动机技术将在实现轻型车辆未来的温室气体（GHG）排放目标中发挥核心作用。但是，这些技术将更加注重优化发动机和燃油，以实现协同增效。系统，因为许多技术将需要更高辛烷值的汽油才能实现其完整的社会和环境效益。协同发动机-燃油系统的最极端示例是按需辛烷值概念。该技术平台在发动机的辛烷值要求相对较低的低负荷和中等负荷下使用源自石油的燃料，而在较高负荷下引入第二种高辛烷值燃料来抑制爆震。本文针对普通汽油E10（RON 93）和高辛烷值E30汽油（RON 101）的按需辛烷值概念，首次进行了汽车燃油经济性和轮毂至温室气体排放的全面研究。实验性油耗图首先用于评估配备有两个替代动力总成的轻型汽车的驾驶循环燃油经济性和温室气体排放量。然后，对由燃料生产产生的上游温室气体排放量进行量化，随后使用蒙特卡洛分析，基于关键输入参数的概率分布函数，对不确定性进行评估。结果表明，与甲醇或乙醇一起使用的按需辛烷值概念通常可提供与高辛烷值E30汽油相当的轮毂温室气体排放量，车辆燃油经济性提高多达10％。使用非传统的发动机校准策略可以最大程度地权衡热效率和燃料能量密度之间的平衡，这也可以显着减少抑制爆震所需的高辛烷值燃料。这增加了在副油箱需要加油之前车辆可以行驶的距离，但是要付出一定的代价，即轮毂的温室气体排放量要比其他方式要高一些。除生物乙醇的土地利用变化（LUC）外，这些发现对上游燃料生产温室气体排放的不确定性基本不敏感。总体而言，这项研究对未来轻型车辆的发动机-燃料系统的设计具有重要意义。这增加了在副油箱需要加油之前车辆可以行驶的距离，但是要付出一定的代价，即轮毂的温室气体排放量要比其他方式要高一些。除生物乙醇的土地利用变化（LUC）外，这些发现对上游燃料生产温室气体排放的不确定性基本不敏感。总体而言，这项研究对未来轻型车辆的发动机-燃料系统的设计具有重要意义。这增加了在副油箱需要加油之前车辆可以行驶的距离，但是要付出一定的代价，即轮毂的温室气体排放量要比其他方式要高一些。除生物乙醇的土地利用变化（LUC）外，这些发现对上游燃料生产温室气体排放的不确定性基本不敏感。总体而言，这项研究对未来轻型车辆的发动机-燃料系统的设计具有重要意义。除了生物乙醇的土地利用变化（LUC）。总体而言，这项研究对未来轻型车辆的发动机-燃料系统的设计具有重要意义。除了生物乙醇的土地利用变化（LUC）。总体而言，这项研究对未来轻型车辆的发动机-燃料系统的设计具有重要意义。