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Dimethyl ether (DME) is an alternative to diesel fuel for use in compression-ignition engines with modified fuel systems and offers potential advantages of efficiency improvements and emission reductions. DME can be produced from natural gas (NG) or from renewable feedstocks such as landfill gas (LFG) or renewable natural gas from manure waste streams (MANR) or any other biomass. This study investigates the well-to-wheels (WTW) energy use and emissions of five DME production pathways as compared with those of petroleum gasoline and diesel using the Greenhouse gases, Regulated Emissions, and Energy use in Transportation (GREET®) model developed at Argonne National Laboratory (ANL).

Because of its abundance and because it offers significant energy and environmental advantages, natural gas has been promoted for use in motor vehicles. A number of transportation fuels are produced from natural gas; each is distinct in terms of upstream production activities and vehicle usage. In this paper, we present greenhouse gas emission impacts of using various natural gas–based transportation fuels. We include eight fuels – compressed natural gas, liquefied natural gas, liquefied petroleum gas, methanol, hydrogen, dimethyl ether, Fischer–Tropsch diesel, and electricity – for use in five types of motor vehicles – spark–ignition vehicles, compression–ignition vehicles, hybrid electric vehicles, battery–powered electric vehicles, and fuel–cell vehicles. In our evaluation, we separate these fuels and vehicle technologies into near– and long–term options to address technology progress over time.

In recent years, various alternative fuels have been proposed and studied for application in motor vehicles. Consequently, fuel-cycle analyses have been conducted to evaluate their energy and emissions effects. In a typical fuel-cycle analysis, feedstock recovery; feedstock transportation and storage; fuel production; and fuel transportation, distribution, and storage are examined. The general belief is that transportation and storage of feedstocks and fuels have small impacts on fuel-cycle results. However, no thorough studies have been conducted to confirm or disprove this belief. Transportation of feedstocks and fuels via different transportation modes requires use of various fuels and generates air pollutant emissions. Storage of liquid and gaseous fuels is subject to fuel losses, which also lead to air pollutant emissions.

This paper presents the results of Argonne National Laboratory's assessment of the fuel-cycle energy and emissions impacts of 13 combinations of fuels and propulsion systems that are potential candidates for light-duty vehicles with tripled fuel economy (3X vehicles). These vehicles are being developed by the Partnership for a New Generation of Vehicles (PNGV). Eleven fuels were considered: reformulated gasoline (RFG), reformulated diesel (RFD), methanol, ethanol, dimethyl ether, liquefied petroleum gas (LPG), compressed natural gas (CNG), liquefied natural gas (LNG), biodiesel, Fischer-Tropsch diesel and hydrogen. RFG, methanol, ethanol, LPG, CNG and LNG were assumed to be burned in spark-ignition, direct-injection (SIDI) engines. RFD, Fischer-Tropsch diesel, biodiesel and dimethyl ether were assumed to be burned in compression-ignition, direct-injection (CIDI) engines. Hydrogen, RFG and methanol were assumed to be used in fuel-cell vehicles.