In a first for the U.S. midstream industry, Enterprise Products Partners LP (EPD) this month loaded combination cargoes of natural gas liquids (NGL) and olefins on the same vessel.

The Houston-based operator said it completed the simultaneous loading of propane and polymer grade propylene into separate compartments on a very large gas carrier at its Houston Ship Channel terminal. The midstream company also simultaneously loaded ethane and ethylene on a vessel at its Morgan’s Point facility southeast of Houston.

Co-loading olefins on larger vessels with NGL allows for more efficient use of available export dock capacity, according to EPD, while also providing freight benefits for petrochemical export customers.

“Loading ethylene and propylene on larger vessels from the U.S. Gulf Coast substantially lowers freight costs and allows U.S. Gulf Coast producers to supply distant markets, such as Asia, more competitively,” said co-CEO Jim Teague. “Enterprise continues to apply its proven midstream model to petrochemicals” so they can focus on their “unique competitive advantages.”

EPD last month said the ethylene export terminal at Morgan’s Point, a joint venture with Navigator Holdings Ltd. from which the first cargo of ethylene was exported at the start of the year, exceeded design interim loading capacity and was on track to export more than 175 million pounds for the month of June.

The partnership expects to complete the construction of an aboveground ethylene storage tank by the end of 2020, bringing the total loading capacity of the marine terminal to 2.2 billion pounds/year. The marine terminal volumes are supported in part by EPD’s pipeline network, which is connected to four ethylene pipeline systems. Three additional connections are expected to be completed by December.