Compressed natural gas (CNG) tranist bus experience survey: April 2009 — April 2010

R. Adams, Marathon Technical Services
D. B. Horne, Clean Vehicle Education Foundation


The U.S. Department of Energy (DOE) and the National Renewable Energy Laboratory (NREL) commissioned this survey to collect and analyze experiential data from U.S. transit agencies with varying degrees of compressed natural gas (CNG) bus and station experience. This information helps DOE and NREL determine areas of CNG transit bus success and priority areas for which further technical or other assistance might be required to enable success.

Clean Vehicle Education Foundation (CVEF) staff and subcontractors developed a battery of questions and identified 10 transit agencies to represent all U.S. transit agencies that use CNG buses, accounting for the diversity in characteristics such as fleet size, management system, station ownership and operation, and geographic location. The survey was conducted onsite.

The study found that the average fuel economy in CNG buses is approximately 20% lower than in diesel buses, although there is reason to believe that this gap will be narrower for new CNG and diesel engines. Based on a recent 12-month period—and after adjusting for energy content, bus fuel efficiency, station maintenance and power costs, and fuel-cost subsidies—the average CNG cost was $1.06 per diesel gallon equivalent.