The focus of this study will be on modeling of the ISO tanks evaporative losses, holding times, and the amount of methane released from the tanks pressure relief/safety valves when the holding time is passed. NASA AVIRIS data and the collected data on methane emission rates from LNG tanks by ground measurements will be used to verify this model. Specifically, the researchers will use the UC Riverside Laboratory for Isotope Measurements in the Environment/Analysis Vehicle for Onroad Capture of Atmospheric Data and Observations mobile observatory to sample roughly a dozen LNG/CNG fueling stations to assess leak rates. Ultimately, the researcher team aims to update the GHG emission factors that indicate the efficacy of LNG/CNG fuels and reassess these fuels role as transition fuels in a 20-year time horizon compared with electrical transportation and other renewable fuel options. Overestimating natural gas as a clean fuel and long term promotion of it by the local governments and the natural gas distribution companies to power passenger cars, trucks, and ships can hinder the real progress toward zero-emission transportation.