The use of dimethyl ether as a transportation fuel - a Canadian perspective

摘要

The key properties that make Dimethyl Ether (DME) attractive as an alternative diesel engine fuel are its high cetane number and its inherent high oxygen content. These properties can improve the engine combustion processes so that significantreductions in the emissions of NO{sub}x, combustion noise and smoke can be achieved such that under most operating conditions the emission levels would be lower than those required by California's ULEV regulations. Moreover, since diesel engines have alower greenhouse gas impact (on a CO{sub}2 equivalent basis) than comparable gasoline engines and the transportation sector is the largest generator of CO{sub}2 emissions in Canada, a DME fuelled diesel engine has the potential to be an attractive primemover for transportation applications.DME is used currently as an environmentally friendly propellant for aerosol sprays and as an ignition enhancer for the cold weather starting of IC engines. The quantities of DME currently produced are therefore small in comparison with the commonly usedtransportation fuels. However, this production will increase as the AMOCO production facility in Venezuela comes on-line. The facility uses a technique developed by the Danish company Haldor-Topsoe for producing synthetic liquid fuels such as DME fromnatural gas. The concept could be particularly attractive to Canadian producers of transportation fuels as Canada has large natural gas resources.In comparison with normal diesel fuel, the volumetric energy content of DME is much lower and its end-user costs could be higher although it is cheaper to manufacture. Nevertheless, due to its superior life cycle impact on greenhouse gas emissions and the opportunity to acquire 'carbon tax' offset credits associated with the recent international environmental agreements, the use of DME or DME-diesel fuel oil blends remains attractive. In this paper the factors involved in the use of DME as a transportation fuel in Canada are identified and the technical and economic areas requiring further investigation are highlighted.