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This paper summarizes the Next Generation Natural Gas Vehicle (NG-NGV) Program that is led by the U.S. Department Of Energy's (DOE's) Office of Heavy Vehicle Technologies (OHVT) through the National Renewable Energy Laboratory (NREL). The goal of this program is to develop and implement one Class 3-6 compressed natural gas (CNG) prototype vehicle and one Class 7-8 liquefied natural gas (LNG) prototype vehicle in the 2004 to 2007 timeframe. OHVT intends for these vehicles to have 0.5 g/bhp-hr or lower emissions of oxides of nitrogen (NOx) by 2004 and 0.2 g/bhp-hr or lower NOx by 2007. These vehicles will also have particulate matter (PM) emissions of 0.01 g/bhp-hr or lower by 2004. In addition to ambitious emissions goals, these vehicles will target life-cycle economics that are compatible with their conventionally fueled counterparts.

SunDiesel fuel is a biomass-to-liquid (BTL) fuel that may have certain attributes different from conventional diesel. In this investigation, 100% SunDiesel was tested both in a Mercedes A-Class (MY1999) diesel vehicle and a single-cylinder heavy-duty compression-ignition direct-injection engine. The SunDiesel's emissions and fuel consumption were significantly better than conventional diesel fuel, especially in nitrogen oxides (NOx) reduction. In the vehicle U.S. Environmental Protection Agency (EPA), Federal Test Procedure 75 (FTP-75), and New European Drive Cycle (NEDC) tests, the carbon dioxide emissions on a mile basis (g/mile) from SunDiesel fuel were almost 10% lower than the conventional diesel fuel. Similarly, in the single-cylinder engine steady-state tests, the reductions in brake specific NOx, carbon monoxide (CO), and particulate matter (PM) are equally significant. Combustion analysis, though not conclusive, indicates that there are differences deserving further research.

SunDiesel™ is an alternative bio-fuel derived from wood chips that has certain properties that are superior to those of conventional diesel (D2). In this investigation, 100% SunDiesel was tested in a Mercedes A-Class (model year 1999), 1.7L, turbocharged, direct-injection diesel engine (EURO II) equipped with a common-rail injection system. By using an endoscope system, Argonne researchers collected in-cylinder visualization data to compare the engine combustion characteristics of the SunDiesel with those of D2. Measurements were made at one engine speed and load condition (2,500 rpm, 50% load) and four start-of-injection (SOI) points, because of a limited source of SunDiesel fuel. Significant differences in soot concentration, as measured by two-color optical pyrometry, were observed. The optical and cylinder pressure data clearly show significant differences in combustion duration and ignition delay between the two fuels.