First Tier 4 Machines Tested On Tennessee Valley Gas Line Construction

By Erin Nelsen, Online Editor | August 2011, Vol. 238 No. 8

Caterpillar's Rex Johnsen shows off the insides of the new Tier 4 excavator to a U.S. Pipeline crew on site in NE Tennessee.

The Tennessee Valley Authority serves 9 million customers in seven states, and two-thirds of its power is generated from coal. So the fact that Spectra Energy is installing a 24-inch gas pipeline through northern Tennessee to feed a TVA power plant is news in itself. But the construction of the North East Tennessee pipeline (NET), due to be completed in September, touches on some of the most discussed issues in the industry.

Emissions Standards Drive Development
Tightening emissions standards are at the core of the project. Barbara Martocci of TVA explains, “We have a vision to be a reliable, clean provider of energy. We have worked to continue providing electricity to the 9 million consumers in the valley, and one of the things we are doing is reducing our dependence on coal while we continue to provide that power.” TVA has one gas plant in middle Tennessee already completed, with a second under construction, and according to Martocci, there’s no question that right now TVA’s usage of natural gas for power generation is increasing, even if the question of fuel sources for future plants remains up in the air.

Rising standards make a strong argument for natural gas. “As we look at our coal plants, the cost to add emissions controls and to meet the regulations that are continuing to come down from the Environmental Protection Agency, we also have to look at all of the other costs associated with operating a plant and make those determinations, what’s the best generation mix for the valley residents.

“That gas that we are going to be using burns more cleanly than coal, so we are able to reduce our emissions.”

The NET also has the privilege of brand-new equipment technology engineered to meet higher emissions standards : eight Caterpillar excavators, six of the 349E model built in Aurora, IL, and two 336Es from the factory in Japan. “The 349Es are the first six that will be delivered anywhere through Caterpillar,” says Mike Dearing, account manager for PipeLine Machinery International, the pipeline specialist Caterpillar dealer. “For the 336Es, U.S. Pipeline is the first North American contractor to get them. We’re going to ship at least six of them out here to Tennessee.”

In addition to several design and comfort upgrades, the excavators align with EPA Tier 4 standards limiting NOx and particulate emissions and requiring decreases of 90% from previous levels by 2014. Filtering and engine design strategies are in development industrywide to determine the best ways to reach these standards. “Caterpillar’s new machines have a diesel particulate filter that takes the soot and burns it to ash when it reaches a certain point in the machine, leaving cleaner air going out into the environment,” Dearing explains.

Asked about the new excavators at the outset of the project, U.S. Pipelines’ project superintendent Dana Bratcher was enthusiastic. “For the pipeline business, the challenge is trying to keep up with equipment technology. These machines have far superior digging power and hydraulics. And I’m excited to see the computerized cameras they’ve got on them. When we can improve safety and performance at the same time, that’s a great thing.”

Of course, new technology isn’t always a smooth ride, and in Tennessee, those shiny yellow excavators were in for a tough maiden voyage.