An assessment of current and emerging refueling-connection-device (nozzle) technologies (both domestic and international) for fueling alternative fuel vehicles is provided. The nozzle technologies discussed are those used for refueling with compressed natural gas (CNG), liquefied natural gas (LNG), and liquefied petroleum gas (LPG, commonly referred to as propane). The discussion covers all types of nozzles for the listed fuels. However, the analytical work focuses on nozzles used in heavy-duty applications, specifically, transit buses.

CNG, LNG, and propane are being used increasingly to fuel transit vehicles. The U.S. Environmental Protection Agency (EPA) and the California Air Resources Board (CARB) have identified a specific area of concern regarding fuel emissions released during refueling with CNG, LNG, or propane at the point when the nozzle is decoupled from the vehicle. The EPA has developed regulations and implementation guidelines for nozzles to mitigate the escape of fuel trapped in the dead space between the nozzle and the vehicle receptacle as it is decoupled. Several nozzle technologies are in various stages of development to address this issue. However, a comprehensive assessment of which current and emerging technologies best resolve this problem was needed.

Research was undertaken by Science Applications International Corporation (SAIC) to (1) summarize existing and proposed regulations, codes, and standards pertaining to the decoupling of CNG, LNG, and propane nozzles; (2) summarize and assess existing and emerging technologies related to CNG, LNG, and propane nozzles; and (3) provide recommendations concerning CNG, LNG, and propane nozzle technologies needed to meet current and proposed regulations. The research inventoried and examined all existing and emerging technologies to address this issue. Technologies addressed included those that are already dedicated to CNG, LNG, and propane refueling, as well as technologies that were developed for other applications but may apply to CNG, LNG, or propane.

The final report has been published as TCRP Research Results Digest 25, " Technology Assessment of Refueling-Connection-Devices for CNG, LNG, and Propane." RRD 25 is available in portable document format (PDF). Double-click on the file below to access this RRD. (A free copy of Adobe Acrobat Reader is available at https://www.adobe.com.)

TCRP Research Results Digest 25