At that level, the U.S. will be the third-largest LNG exporter in the world behind Australia and Qatar.

The United States began exporting LNG from the Lower 48 states in early 2016 when Houston-based Cheniere Energy shipped its first cargo from its Sabine Pass LNG terminal in Louisiana. Virginia-based Dominion Resources became the the second company to do so after shipping its first cargo from the company's Cove Point LNG export terminal in Maryland in March.

Four companies are expected to bring at least 18 LNG production units known as trains into service over the next 12 months.

Cheniere accounts for three of them. The first train at the company's Corpus Christi LNG facility reported its first shipment on Tuesday morning, while the fifth train at its Sabine Pass facility is expected send its first shipment by month's end. The second train at the company's Corpus Christi facility is expected to come into service during 2019's second quarter

Meanwhile, all three trains at Sempra Energy's Cameron LNG in Louisiana are expected to be in service by the end of next year.

Houston-based Kinder Morgan is expected to bring 10 small and modular production units at its Elba Island LNG facility near Savannah, Ga., into service over the next 12 months.

The first two trains at the Freeport LNG facility near Houston are expected to be in service by the end of next year.

And there are still more projects in the pipeline. Freeport LNG and Corpus Christi LNG are expected to have their third trains in production by 2020 and 2021 respectively. There are also several LNG export terminal projects moving through the federal approval process.