In the future, there should be a need for more efficient heavy duty vehicles used for mass transit and transporting goods across a country. In addition these vehicles should be able to perform better (ie increased gas mileage and lowered emissions). One fuel that has been tested since 1995 in diesel type vehicles is Dimethyl Ether, which has been proven to meet fuel emissions standards and perhaps fuel efficiency ones as well. DME (dimethyl ether) can operate in diesel engines with minor modifications to the fuel injection system. Just as interesting, DME can also be mixed with LPG (Liquefied Petroleum Gas) to operate in ignition combustion engines (ie gasoline based). DME can be mixed at 30 % as an additive to LPG and engine modifications might also be needed such as new engine designs that incorporate spark and compression ignition (called Homogeneous Charge Compression Ignition Engine - HCCI [ 1. K. Yeom et al 2009 ]. The chemical structure of DME is shown in the image above. DME has favorable engine performance characteristcs because of its chemical/physical properties such as a low boiling point & high cetane number. DME also combusts very clean or in other words it is Sootles, meaning little to no smoke or particulates are emitted. DME also has projected lower combustion emissions of carbon dioxide, since it has a high oxygen content, it also more easily meets 2007 nitric oxide diesel engine standards due to more exhaust recirculation [ 2. L. Savadkouhi et al year ]. Another interesting fact is that DME can be produced at affordable prices using synthesis gas obtained from natural gas. According to the International DME Association, DME maybe at least 1.5 times cheaper to produce than diesel fuel and can also be simulataneously produced with methanol or converted directly from methanol.
The need to have a fuel distribution network and a good heavy duty vehicle infrastructure based on DME in Europe created a joint effort collaboration called the AFFORHD Project. In fact, there should also be heavy demands for DME trucks and buses in Japan and China. This has prompted companies like Nissan and Volvo to built diesel vehicles that can operate on DME. Nissan based trucks have already been built and have been tested by the National Traffic Safety and Environmental Laboratory where they passed US 2010 heavy duty vehicle emission standards. Increased pressure to have cleaner burning vehicles across the world has already got Europe and Asia pivoted to mass produce DME vehicles between the years 2015 - 2020. Dimethyl ether also has other similar uses to the petrochemical industry where it can serve as a energy production fuel or used as a chemical feedstock for making plastics. DME can be combusted in Gas Turbines for Electric Power Generation. It can be used as chemical feedstock to produce Polypropylene plastics. DME can also be mixed with LPG in order to be used a heating fuel in homes. It is usually mixed at about 20 % with LPG. Other physical properties that make DME a favorable fuel for multiple uses is its low viscosity, high cetane number and low octane number. Overall, DME can serve as a legitimate diesel fuel substitute with the advantage of having better fuel characteristics, performance and lower emissions. Vehicles such as these on the American Highways would be favorable since they may more easily pass more recent American fuel efficiency and emission standards as mentioned above.
REFERENCES
1. "Knock Characteristics in Liquefied Petroleum Gas (LPG) - Dimethyl Ether (DME) Homogeneous Charge Compression Ignition Engine", Energy Fuels vol 23 no 4 pgs 1956-1964 [2009] by K. Yeom and C. Bae
2. "Performance and Combustion Characteristics of OM314 Diesel Engine Fueled with DME : A Theoretical and Experimental Analysis" Journal of Engineering for Gas Turbines and Power vol 132 no 9 pgs 92801-92806 by L. Savadkouhi, S.A. Jazayeni, N. Shahangian, J. Tavakoli
Photos taken from the Picassa Web Album
KEYWORDS: Dimethyl Ether, Diesel Fuel Substitutes, Nitric Oxide Emission Standards, Liquefied Petroleum Gas, Simultaneous Methanol and Dimethyl Ether Production, Cetane Number, Viscosity, Homogeneous Charge Compression Ignition Engine, Gas Turbine Fuel, Home Heating Fuel, National Traffic Safety and Environmental Laboratory, AFFORHD, Nissan & Volvo DME trucks, Sootless emissions, low carbon dioxide emission fuels
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