Attention, all school bus operators who bristle at the thought of transitioning from diesel power to alternative fuels, there is relief on the horizon.
Renewable Diesel (RD), which is available in parts of California, is turning heads, as it promises to deliver, at the very least, the same fuel economy and performance of ultra low sulfur diesel. CAL-START, in a recent webinar, claimed that RD also reduces greenhouse gas emissions by 65 to 90 percent.
Pat O'Keefe, CEO and president of NexGen Fuel, a subsidiargy of Golden Gate Petroleum, said that such a reduction in GHG is a "huge benefit" for a drop-in fuel. That means RD meets the same ASTM D975 standard for ULSD and engine manufacturer requirements.
Renewable Diesel is similar to biodiesel in that it's derived from waste vegetable oils and waste animal fats, but the similarities stop there. Unlike biodiesel, RD doesn't have the same cold weather issues since RD doesn't gell, having a cloud point of -20 degrees.
They also differ in how they are made, with RD refined from biomass through various processes, such as hydrotreating, thermal conversion and biomass-to-liquid. Biodiesel, on the other hand, is produced using feed stock in a process called transesterification.
Additionally, O'Keefe said that RD reduces particulate matter by a third, along with its ability be used in all modern diesel engines without any need of modifications.
So far, the only school district using RD is San Jose Unified, which is located south of San Francisco. Andrew DeBolt, lead equipment mechanic for San Jose Unified, told School Transportation News that the district is in the process of transitioning its entire fleet of 72 buses to RD with plans to only purchase diesel buses in the future.
Nearby in Oakland, the municipal fleet is the first to adopt RD. Fleet Director Richard Battersby, who will present on the benefits of RD at next month's STN EXPO, said that operators don't need to flush existing fuel tanks to use the renewable fuel. He added that it is a little more expensive than traditional diesel at an increase of about 10 cents per gallon, and availability is still an issue.
But Battersby said that he expects the reduced soot emissions to improve performance of DPFs and the affect on his operation's bottom line to be worth it.
"We expect in the long run to lower maintenance costs," he said.
He also pointed to RD's higher cetane number of 75 to 90. In comparison, petroleum diesel has a cetane number of 40 to 55, while biodiesel ranges from 50 to 65.
Read more in the July issue of School Transportation News magazine.
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