Lower Cost and Lower Emissions of Biodiesel Add Up

Rochester Public Transit saves money and reduces air pollution by using biodiesel in its fleet.

There are a lot of reasons Rochester, Minnesota, runs its public buses on biodiesel blends. But when the city made the switch nearly 20 years ago, two benefits rose to the top.

“One was cost, and the other was lowering emissions,” says Tony Knauer, the city’s transit and parking manager.

Today, those are still the two chief reasons Rochester Public Transit not only uses biodiesel in its 52-bus fleet but has also increased to a B20 blend, meaning the fuel contains 20 percent biodiesel. In 2016, the city paid 8 cents per gallon less for B20 than it would have for B10, and it saved 17 cents per gallon over what it would have paid for 100 percent petroleum diesel. That adds up fast for a fleet that consumes 300,000 gallons of biodiesel per year and is the largest fuel user among the city’s fleets.

“Savings in operating expense are important to any enterprise whether public or private,” Knauer says. “Fuel is a major expense in our budget. At our current usage, a 10-cent-per gallon decrease over a year is a $30,000 savings.”

Public wants cleaner fuels

The other part of the equation is the environment. Rochester Public Transit moved from B10 to B20 in June 2016 at the recommendation of the American Lung Association in Minnesota, which promoted the reduction in particulate matter, hydrocarbon and carbon emissions the move would bring. The bus fleet now uses B20 in the warmer months and B5 in the winter.

“We decided to start using B20 because we know the mayor and the city want Rochester to be environmentally friendly,” Knauer says. “Also, the fuel performs well. It has not been detrimental to our engines.”

Having cleaner air and being sustainable takes on added importance in Rochester because the town is home to the renowned Mayo Clinic. A significant portion of the population works in the health care industry, and people from all over the world come to Rochester for treatment.

“If people were to look out their windows and see black smoke pouring out of buses, that would not be acceptable,” Knauer says. “We are very sensitive to that.”

Mayo Clinic also boosts ridership on city buses. Rochester has a population of 110,000, but 40,000 people work downtown, where Mayo is located. Many of them ride the bus, and the Rochester Public Transit hub is in the center of the medical campus.

Fleet performance stays strong

Rochester Public Transit has achieved these financial and environmental benefits from biodiesel with no loss in performance.

“We haven’t experienced anything negative with biodiesel,” says Roger Ritchie, the transit system’s fleet manager and a diesel mechanic. “Since switching to B20, we’ve had no engine issues. We haven’t had any issues with fuel filters. And the lubrication from biodiesel has been a good thing given the lack of lubricity in modern diesel fuel.”

The city studied compressed natural gas (CNG) in 2014 and 2015. The cost of a high-pressure CNG fueling station was estimated at $3 million. Retrofitting the maintenance shop was estimated at another $1 million. Knauer says that since that study, the margin between biodiesel and CNG prices decreased, which has made the return on investment for CNG longer. The city council decided to wait and continue to monitor the development of alternate fuels. Knauer says that when you purchase a bus with a certain fuel system you are committed to that fuel type for 15 to 20 years.

“When we were considering going to B20, all of the arguments environmentally, on the engine side and cost were positive,” Knauer says.


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