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Japan automakers going slow with biodiesel; JAMA maintains stance on B5 as maximum for now

JAMA cites the poor oxidation stability of high-level biodiesel blends, highlighted in the JATOP findings, in sticking with B5 levels. PME= palm oil methyl ester, RME = rapeseed methyl ester, SME = soy methyl ester, WME = waste cooking oil methyl ester, FTD = Fischer-Tropsch diesel, HBD = hydrogenated biodiesel. Source: JATOP.Click to enlarge.

The Japan Automobile Manufacturers Association (JAMA) is maintaining its stance on B5 (5% biodiesel, i.e., fatty acid methyl ester, blends) as the maximum until further findings and market observations on the use of B7 are reported.

JAMA bases its postion on the results of study from the Japan Auto-Oil Program subsidized by Japan’s Ministry of Economy, Trade and Industry (METI). JATOP was organized by the Japan Petroleum Energy Center to develop automotive and fuel technologies best suited to simultaneously settle three issues—“Reducing CO2 emissions”; “Fuel diversification” and “Reducing motor vehicle emissions”—and to develop high accuracy air quality simulation models and facilitating their exploitation.

JATOP, which kicked off in fiscal 2007, was a five-year collaborative research program conducted by the oil and auto industries, and was the successor to the JCAP (Japan Clean Air Program), which was conducted between fiscal 1997 and fiscal 2006 with the main goal of improving air quality by reducing motor vehicle exhaust emissions.

Major components of the JATOP program were:

  • A study on the use of high biodiesel blends in diesel vehicles;
  • A study on the enhanced use of biofuels in gasoline vehicles; and
  • A study on future fuels for diesel vehicles.

JAMA endorses the automotive use of FAME-blended diesel from fossil fuel conservation and energy security points of view. On the other hand, JAMA believes it is imperative that FAME-blended diesel has the equivalent quality when compared to conventional diesel fuels, so vehicles can achieve satisfactory safety and emissions performance.

Other than “fit-for-purpose” specifications for FAME and FAME-blended diesel fuel, diesel engine vehicles for the past century have been designed and developed to be used with conventional diesel fuel. In most countries, the safety, performance and emissions of such vehicles have also been tested for road-worthiness or type-approval with conventional diesel. Therefore, appropriate blending of biodiesel for general diesel engine vehicles is defined, in essence, as one that has proven its equivalence to conventional diesels in terms of producing same standards of emissions, safety and performance, as per a diesel vehicle running on conventional diesel. In other words, the key for automakers to accept biodiesel as conventional diesel, lies in closing the quality gap between biodiesel and conventional diesel fuels.


The JATOP study on biodiesel focused on 7 areas of potential impact stemming from the use of higher blend levels:

  1. Impact on fuel properties
  2. Impact on stability
  3. Impact on emissions
  4. Impact on exhaust aftertreatment systems
  5. Impact on low temperature operability
  6. Impact on engine oil
  7. Impact on reliability.

Very broadly, the research identified several technical issues on the use of biodiesel-conventional diesel blends above 5% biodiesel. With the use of B10/ B20 FAME, concerns were raised about material compatibility, storage stability at room temperature, oxidation stability and stability during long parking periods. The study also found issues with large increases in NOx emissions with high FAME blends (30, 50 and 10%).

In terms of fuel quality, the JATOP study concluded, it would be preferable to convert FAMEs through hydrogenation and other treatments into hydrocarbon fuels the quality of which is equivalent to diesel fuel. This, suggested the research team, is because properties of FAME are too varied by feedstock, composition, etc. to enable uniform quality control.

JAMA particularly looked to the JATOP study findings that the double bonds found in the unsaturated fats of all FAME feedstocks, which leads to poor oxidation stability and easier low-temperature solidification, is the key that contributes to differences in quality between FAME and conventional diesel.

It is well known that poor oxidative stability leads to a variety of problematic degradation by products, including corrosive, low molecular weight acids and biopolymers, which are the principal cause of sludge and lacquer in diesel fuel injection systems, the JATOP study also found diesel vehicles using above B5 encountered issues of fuel filter plugging, engine oil dilution and degradation. Foreign matter was found to adhere on the suction control valve after long parking periods, which in-turn led to idling trouble after a cold engine start up.

To close the quality gap between biodiesel and conventional diesel fuels, for the assurance of safe performance in all diesel vehicles, JAMA has recommended the blending of no more than B5, regardless of feedstock, and the application of oxidation stability enhancing additives to secure its quality. Meanwhile, HVO(Hydro-treated vegetable oil) or BTL (biomass to liquid) that have no inherent double bonds or oxidative stability issues, are strongly recommended as blend stock for the production of FAME-blended diesel with more than a 5% FAME content equivalent.

… even though Europe has increased its mandatory blending of biodiesel to B7 with strengthened oxidation stability requirements in 2009, JAMA remains in its stance on B5 until further findings and market observations on B7 are reported.




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