Furthermore, there is reason for optimism that the drive-cycle-based efficiency of ICEs can be improved, both through engine-based advancements and through hybridization, such that the fuel consumption of engine-powered vehicles can be significantly reduced. Also, the engine has a sophisticated and mature manufacturing basis and is capable of using a range of fuels, from petroleum to liquid-based biofuels to gaseous fuels, derived from a variety of feedstocks. Liquid fuels offer the attractive characteristic of having very high energy per unit of mass and energy per unit of volume. This characteristic facilitates long-range and/or sustained high-power-output vehicle operation. There will be, for many decades, applications for which the ICE-powered vehicle is the best choice.
Life-cycle analyses reported in the literature, such as that shown in Figure 3-1, suggest that total greenhouse gas (GHG) emissions for future high-technology ICE-powered vehicles1 will be made competitive with non-ICE-powered vehicles on a basis of total GHG life-cycle emissions, while still meeting stringent air quality regulations (Weiss et al., 2000; Bandivadekar et al., 2008). Uncertainty bars in Figure 3-1 denote well-to-tank GHG emissions for electricity generated from coal (upper bound) and natural gas (lower bound). For the well-to-tank GHG emissions from hydrogen fuel cell vehicles (HFCVs; shown as “FCV” in Figure 3-1), it is assumed that the hydrogen fuel is steam-reformed from natural gas at distributed locations and compressed to 10,000 psi.
The advanced combustion and emission control (ACEC) technical team of U.S. DRIVE is the Partnership’s technical interface with the research community’s activities in advanced combustion and emission control. The goals, technical targets, and program structure of the ACEC technical team build on those from the FreedomCAR and Fuel Partnership, which in turn built on the goals and targets from the Partnership for a New Generation of Vehicles (PNGV). For the FreedomCAR program, the advanced combustion and emission control targets and results were as follows:2
• Peak engine brake thermal efficiency (BTE) of 45 percent
—This BTE was demonstrated with a light-duty diesel engine and an H2-fueled ICE.
• Oxides of nitrogen (NOx) and particulate matter (PM) emissions for light-duty diesel engines at Tier 2 Bin 5 (T2B5) standards
— Twelve vehicle models that met this target were commercially available in the 2012 model year (MY).
1 Hybrid electric vehicles and plug-in hybrid electric vehicles are included in this classification because the engine still plays a major role as the energy converter between the fuel energy and work delivered to the wheels.
2 R. Peterson, General Motors, and K. Howden, Department of Energy, “Advanced Combustion and Emission Control Technical Team,” presentation to the committee, January 26, 2012, Washington, D.C.