NuStar Energy L.P. engages in the terminalling, storage, and marketing of petroleum products in the United States and internationally.

The company also engages in the transportation of petroleum products and anhydrous ammonia.

It operates through three segments: Pipeline, Storage, and Fuels Marketing.

The Pipeline segment transports refined products, crude oil, and anhydrous ammonia.

The Storage segment owns terminal and storage facilities, which offer storage, handling, and other services for petroleum products, crude oil, specialty chemicals, renewable fuels, and other liquids; and pilotage, tug assistance, line handling, launch, emergency response, and other ship services.

The Fuels Marketing segment is involved in bunkering operations in the Gulf Coast; blending operations; and purchase of petroleum products for resale.

As of December 31, 2021, it had 3,205 miles of refined product pipelines and 2,230 miles of crude oil pipelines in Texas, Oklahoma, Kansas, Colorado, and New Mexico; a 2,050-mile refined product pipeline originating in southern Kansas and terminating at Jamestown, North Dakota; a 450-mile refined product pipeline originating at Marathon Petroleum Corporation's Mandan, North Dakota refinery and terminating in Minneapolis, Minnesota; a 2,000-mile anhydrous ammonia pipeline; and 29 terminal and storage facilities, which offer approximately 44.2 million barrels of storage capacity.

The company was incorporated in 1999 and is headquartered in San Antonio, Texas.