Brazil's Diesel Fuel Alternatives

Brazilian researchers explored a number of diesel fuel alternatives in the late 1970s/early 1980s, including ethanol and vegetable oil.

| July/August 1980

Not long ago, two of MOTHER EARTH NEWS' editors returned from Brazil, where they had been investigating that country's massive effort to replace virtually all of its presently imported petroleum fuels with homegrown energy in the next decade or so. Clearly, the forward-thinking South American nation sees the "shape of things to come" ... and has chosen to take a positive course of action rather than merely fret about the future.

One of the major concerns of the Brazilian people is the availability of diesel fuel, since 80% of that country's goods (and most of its commercial passengers) are transported by heavy trucks and buses. Because even less diesel oil than gasoline can be gleaned from a barrel of crude petroleum, it's easy to understand why efforts are being made to look for viable domestic diesel fuel alternatives.

Appropriately enough, Mercedes-Benz (which supplies much of South America with diesel vehicles) of Brazil has been busily engaged in researching alternative fuels since early in 1973 ... and as of September 1979 has been testing its experimental fleet commercially, in the field, with excellent results.

Naturally, because Brazil has been so heavily involved in what they refer to as the "pro-alcohol" program, engineers at M-B have been primarily interested in running their diesel engines on ethanol ... but they've also been actively working with two other types of fuels that show great promise: a combination of diesel oil and gasoline, and a mixture of vegetable oil and diesel fuel.

How They Did It

Standard diesel fuel has specific properties that make it suitable for use in self-firing internal combustion engines. The "liquid energy" provides needed lubrication, ignites easily, flows freely, burns with a minimum of residue, resists pre-ignition, and is relatively nonpolluting. Ethanol meets all these requirements but two: It doesn't have the lubricative qualities of petroleum distillates, and its cetane number (which is used to indicate the ability of a fuel to ignite quickly after being injected into the combustion chamber) is only about 10. (A diesel engine requires a fuel with a minimum rating of 45.)

In order to provide the necessary lubrication to the engine's injector pump, the Brazilian scientists merely routed an additional oil line from an existing fitting in the block, then on to a filter, and then into the pump itself. At the same time, the researchers installed a return tube to allow the pressurized engine oil to drain back into the crankcase.

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