Challenges to completion

More than 1,000 workers were on site at the peak of construction, according to Valero, and blending input from the project's diverse group of engineers and contractors has been a challenge. Just coordinating equipment delivery was a major task, Richard Industrial Group tells ENR.

There have been other tensions and delays. The project was considered a favorite of the Energy Dept., which backed a $241-million loan guarantee for the facility in 2011. But the plant is one of several advanced biofuels projects that have turned down DOE support. According to one project source who declined to be identified, "too much bureaucracy and red tape" prompted Valero to reject the loan.

"We think this project would still be several years out if Valero had accepted the partnership of the DOE," says Denny Robertson, lead process engineer for Richard Industrial Group.

Another challenge involved "marrying" what is essentially a new chemicals plant to an existing oil refinery. "Connecting the Kansas City Southern rail line to a new spur right over the top of existing gas links and pipelines from the renewable diesel plant to the oil refinery was a major obstacle," Mayeux says. "We had to construct a foundation and footings for a 500-foot bridge and drive piles in the pipeline right-of-way. In between the piles we had to place precast panels and set the ballast on top. The pipeline was between the piling units."

DOE says Diamond Green Diesel "will be the first application of its kind in the U.S. to use an innovative hydrotreating/isomerization process from Desmet Ballestra Group and UOP known as 'ecofining,' which converts processed feedstock into high-quality diesel."

Isomerizations are processes in which atomic components of a molecule are rearranged, but not changed, with heat in the presence of a platinum catalyst. These are used in conjunction with UOP's hydrotreating technology, which hydrogenates biological matter, like waste grease, to produce a hydrocarbon molecule.

For Triad Electric, getting these different technological components to communicate using Rosemount process controls has been difficult, says Charles Browning, the firm's project manager. "We're crossing the world of industrial construction with food processing and merging these components in a new way."

Conflicts also emerged in standards used for process controls and electrical instrumentation. "The pretreatment skid [which purifies the greases and fats to become suitable for processing] is a self-contained, controlled environment that you have to merge with the other components of the plant," says Browning. "To get all of these parts communicating correctly back to the control room has been a challenge."

The project has fallen behind schedule. Turner had previously stated it would be finished by December 2012, but problems with the plant's pipe and tubing work has pushed completion back to the second quarter of this year. In a recent earnings call, Randall Stuewe, CEO of publicly held Darling, said that if the plant had been operational in 2012, it would have increased the company's earnings more than 30%. Darling will be the exclusive provider of raw materials for the facility.