September 28, 2016

Natural gas vehicle stakeholders have expressed concerns with the periodic inspection and end-of-life decommissioning safety requirements for compressed natural gas (CNG) fuel tanks. A Clean Cities project—the Compressed Natural Gas Vehicle Fuel Tank Safety Initiative—addresses these concerns with a suite of resources, including a new 15-minute training video on CNG Fuel Tank Defueling, Decommissioning, and Disposal.

CNG fuel tanks have a useful life of 15, 20, or 25 years, depending on their construction and how they were certified by the original manufacturer. Because there is no way to safely "requalify" tanks for extended use, once a tank reaches its expiration date, it must be decommissioned.

Performing a regular safety inspection of the CNG tanks is also a critical maintenance requirement for CNG fuel systems.

The video features four chapters. The introduction provides an overview of CNG fuel tank end-of-life issues and highlights the importance of regular tank inspections. The three subsequent chapters present best practices for the steps required for an expired CNG fuel tank: defuelingdecommissioning, and disposal.

Other helpful resources from the project are forthcoming and include a webinar, updates to the CNG Fuel System and Tank Maintenance pages on the AFDC website, presentation materials, and a guidance document on CNG fuel tank defueling, decommissioning, and disposal.

Together, these resources will accelerate the sharing of best practices and provide education on proven approaches to safely managing CNG fuel tanks. Long-term goals include evaluating and characterizing the conditions of CNG fuel tanks at the end of life under real-world operating conditions, considering options for the identification and tracking of in-use fuel tanks over their lifetime, and developing recommendations on research and development for improved fuel tank technologies that will enhance safety and performance.

For more information about the CNG tank initiative, contact Clean Cities Project Leader Kay Kelly at Kay.Kelly@nrel.gov.