Abstract: Disclosed herein is a pressure control system for a liquid natural gas (LNG) storage tank. The pressure control system comprises a second heat exchanger, comprising a first inlet fluidly coupled with the LNG storage tank and a first outlet fluidly coupled with the LNG storage tank. The pressure control system also comprises a coolant, fluidly coupled with a second inlet of the second heat exchanger. The heat exchanger is configured to transfer energy from the coolant to the LNG from the LNG storage tank to vaporize the LNG into compressed natural gas (CNG). The pressure control system also comprises a first control valve selectively operable to allow LNG to flow from the LNG storage tank to the heat exchanger and to allow CNG to flow from the heat exchanger to the LNG storage tank when a pressure within the LNG storage tank is below a lower pressure threshold.