NREL Evaluates Propane-to-Electricity Shuttle Conversion at Zion Park


The U.S. National Renewable Energy Laboratory (NREL) says it is evaluating the drive-cycle characteristics of a fleet of propane-powered shuttle buses operating at Zion National Park. With the propane fleet aging and associated maintenance costs rising, NREL is now working with the National Park Service (NPS) to use this drive-cycle information to optimize the conversion of 14 of its propane buses to run on electricity.

According to NREL, the NPS originally deployed the propane buses in 2000 to reduce congestion along the park’s main traffic corridor. Nearly 60% of NPS-owned vehicles currently operate on alternative fuels.

“Each bus pulls a passenger trailer. The open-air nature of the bus/trailer setup, which accommodates 68 passengers, is popular among park visitors,” says NREL’s Robert Prohaska. “By working with NREL to make an informed, data-driven decision, NPS can transition to a new vehicle technology without sacrificing operational capacity or the positive visitor experience.”

To support the transition, NREL researchers are gathering operational data from the propane buses via onboard logging devices to understand dispatching patterns, evaluate the effect of road grade on system requirements, and determine optimal power and energy storage requirements based on the fleet’s unique operation.

NREL says it will process and analyze the data using specialized tools – including the Drive-Cycle Rapid Investigation, Visualization, and Evaluation tool and the Future Automotive Systems Technology Simulator – ultimately producing operational drive-cycle statistics to be used by prospective retrofitters as the NPS solicits bids for converting the propane buses to run on electricity.

NREL’s fleet test and evaluation team is conducting this work in partnership with the U.S. Department of Energy’s Clean Cities National Park Initiative, which supports transportation projects – such as alternative fuel and fuel-efficient vehicle deployments and idle-reduction outreach campaigns – that educate park visitors about the benefits of reducing petroleum use and vehicle emissions.

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