A novel blend of fuels devised by a small public transit agency has resulted in cleaner emissions and better cold-weather reliability.

Ben Franklin Transit (BFT) in Richland, WA, in 2007 began an experiment funded by the National Renewable Energy Laboratory and Washington State Department of Ecology. This program was led by Richard G. Ciccone, BFT manager of fleet, facilities, and special projects, who shared his experience in an interview at the 2009 APTA Bus & Paratransit Conference in Seattle.

BFT blended 71.6 percent ultra-low-sulfur diesel (ULSD), 20 percent biodiesel, 7.7 percent ethanol, and .7 percent of a proprietary oxygenated diesel additive trademarked as O2 Diesel, then tested the cross blend in seven different bus engines from the system’s fleet, including a 6V92—“one of the dirtiest engines there is,” Ciccone noted.

The results? Independent lab tests found that exhaust temperatures were an average of 6.5 degrees lower with the blended fuel; fuel temperature was 18 degrees lower on average; and the horsepower loss was less than 4 percent. Fuel consumption was approximately the same as ULSD, Ciccone said, and engine oil temperature was 3 degrees lower.

This cleaner-burning fuel with a higher oxygen content made for a more complete fuel burn, he explained, resulting in less exhaust smoke and considerably less soot in the oil. Oil analysis showed a soot content of less than one-half percent with the cross-blended fuel, substantially lower than the nearly 4 percent found with regular diesel. This could triple the length of time buses can go between oil changes, according to Ciccone.

He noted that previous tests had shown that ethanol added to diesel fuel reduces the content of nitrous oxide, carbon monoxide, particulates, and smoke in diesel exhaust. Biodiesel made from canola oil or soybeans, which also showed good emission reductions, is a biodegradable organic solvent; biodiesel is even used to clean up asphalt paving equipment on highway projects, he said.

The O² Diesel additive is the emulsifier, which allows B20 and ethanol to blend with the ULSD. In turn, the lower flash point of ethanol allows for easier cold-weather starts and helps the thicker biodiesel to flow at temperatures down to 15 degrees below zero Fahrenheit.

In addition, the blended fuel requires no infrastructure investment or mechanical alterations whatsoever. “You can just put it in the tank and go,” he said.

The one impediment Ciccone reported to widespread use of the cross-blended fuel is the rising prices of the component fuels and additive at a time of record diesel fuel prices. However, this could be offset over the long term by longer vehicle life and reduced service costs—and the prices may eventually come down.

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