Recent research into methane emissions from the liquefied natural gas (LNG) supply chain has revealed uncertainty in the overall greenhouse gas emissions reduction associated with the use of LNG in heavy-duty vehicles. Methane is the main component of natural gas and a potent greenhouse gas. This study investigates the impact of five methods used to offload LNG from a tanker truck to an LNG refueling station and estimate the amount of fugitive methane emissions. The LNG offloading process time, and the final pressures of the tanker truck and refueling station are considered to evaluate the performance of the LNG offloading methods. The modeling results show that the LNG transfer by using a pressure buildup unit has a limited operating range and can increase methane emissions by 10.4% of LNG offloaded from the tanker truck. The results indicate that the LNG transfer by using a pump and an auxiliary pressure buildup unit without vapor return provides the shortest fuel offloading time with the lowest risk of venting methane to the atmosphere.

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