Research Projects

Project at a Glance

Project Status: complete

Report Published August 1993:

Title: Methanol fuel additive demonstration

Principal Investigator / Author(s): Fanick, E. R.

Contractor: Southwest Research Institute

Contract Number: A832-123


Research Program Area: Emissions Monitoring & Control

Topic Areas: Mobile Sources & Fuels, Stationary Sources


Abstract:

One potential strategy for achieving significant reductions in motor vehicle emissions is the replacement of conventional fuels with methanol; however, safety and toxicity problems associated with Ml00 have prevented its wider acceptance and use as a clean motor fuel. Some of these problems include:

* Poor vehicle cold-starting
* Low fuel lubricity
* Flammability of saturated vapors in storage and fuel tanks
* Low flame luminosity
* Human toxicity by inhalation, absorption through the skin, or ingestion.

Additives to the fuel have been proposed as one means of alleviating these problems by creating desirable properties to nullify or offset the negative effects of the fuel. However, these additives, while improving the properties of the fuel, should not reduce the benefits of neat methanol as a clean motor fuel. This final report discusses the results of an extensive literature search for additives to address the items listed above; a laboratory test program emphasizing flame luminosity, fuel lubricity, and flammability; a comparison of the generated laboratory data to real world situations; and hydrocarbon speciation of exhaust emissions from a vehicle operating on potential additive packages. The literature search identified potential additive candidates, with suggested concentrations, to improve significantly the safety and reduce the toxicity of the fuel without altering its potential for emissions reduction. These candidate additives were also screened for possible formation of known or suspected toxic combustion products. In the laboratory test program, the candidates were screened for their effectiveness in improving the fuel properties. The flame luminosity was measured with a system specially designed to monitor the light produced by the flame in terms of foot-candles. Concentrations were originally held below 5 percent by volume, but later in the program results indicated that higher concentrations and multiple component additives were required to achieve a luminous flame throughout the burn Lubricity was measured with a Ball-on-Cylinder Lubricity Evaluator (BOCLE). For the flammability limits, a device was designed to determine the presence of flammable vapors above the liquid at different concentrations. This work led to the identification of potential additive packages for M100, with each package being evaluated for synergistic effects using same test procedures. Toluene and a proprietary alcohol soluble solid material yielded the greatest potential for luminosity improvement in the initial effort (Task 1 - additive package concentrations limited to 5 percent), while fatty acids and organic amine salts were effective at improving the lubricity of the fuel. Butane and butene lowered the flammability limit below 18įC. In the expanded effort (Task 1 Expansion - no limit on the additive package except to cost less than 125 percent of the gasoline portion of M85), potential additives were investigated at higher concentration. Two blends (4 percent toluene plus 2 percent indan. and 5 percent indan plus 5 percent cyclopentene) were selected for further study and were burned under outdoor conditions and compared to neat methanol, neat ethanol, and MS.5 under the same conditions. Each burn was performed on five different surfaces: concrete, asphalt, sheet metal, grass, and soil. Speciated hydrocarbon exhaust emissions from a Volkswagen Jetta fueled with two additive blends were compared to speciated emissions from the same vehicle operating on M100, M85 and an "industry average" gasoline. In this vehicle, the additive blends did not significantly decrease the ozone-forming potential when compared to M85. The cost of these additive packages would increase the price of the fuel by more than 15 percent of the current MM fuel cost at the pump in California. Lower feedstock costs or cheaper alternative additive components would reduce these costs.


 

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