Sustainable Underground

NYU Modernizing it’s Underground Power Plant

A major expansion will quadruple the number of buildings served by New York University’s underground power plant.

New York University will update and expand its 1980s-era heat and power plant to serve more of the campus while replacing diesel and fossil-fuel burning equipment with a more energy-efficient gas cogeneration system.

“We wanted to do something to increase capacity and do something environmentally friendly and in line with the university’s sustainability efforts,” says Martin Kushner, project director for NYU. “It also will give us more reliability.”

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The existing, underground plant currently serves seven buildings with two diesel generators and a steam generator with a fossil-fuel burning boiler. The facility also provides back-up power to five buildings.

The new plant will produce 13.4 megawatts of power and provide electrical service to 29 buildings with two Solar Taurus 60 gas turbines. Heat from the gas turbines will feed the existing central heating plant, which serves 40 buildings. The project will allow the school to decrease its reliance on the city’s Con Edison Co. power grid, increase reliability of its power supply and reduce costs and air emissions.

“The plant will be connected in parallel with the utility,” Kushner says. “If the plant goes down, the utility picks up, and if the utility goes down, the plant picks up. Right now, if the cogeneration goes down, we need to transfer to the utility.”

NYU estimates the new $120 million plant will reduce the amount of regulated pollutants produced by 85% and decrease greenhouse gas emissions by more than 5,000 tons annually.

The university will stop using its diesel generators, although they will remain in place for backup. Heat recovered from the gas turbines will power the steam generator.

Project plans

The new plant will be built below grade, in a 210- by 40-ft concrete vault, under a plaza along Mercer Street between Third and Fourth streets, and will connect with the existing plant located below Warren Weaver Hall.

“We were lucky to have a plaza and a building set back from the street,” Kushner says. “It was an opportunity for space that otherwise I don’t see where we could have installed them.”

Nearby, the university operates central heating and chilled water facilities. All of the major equipment is in close proximity, making it easier for operations.

Mike Thornton, project manager for Vanderweil Engineers of New York, adds, “The reason we put [the new addition] there is to take the waste heat from the gas turbine through a heat-recovery process and connect to the existing system that resides in the basement with the present cogeneration equipment.

“It’s quite common to put a new cogeneration plant near the existing facilities’ boilers in a central plant or on a distribution line. You can do it as long as you tie the steam pipes to the existing facility. This is the only building with steam piping.”

Plant construction

Construction manager Skanska USA Building of New York began utility relocations in summer 2007.

The company will excavate to a depth of about 55 ft and then pour a 3-ft-thick floor and 2-ft-thick walls. The two-level vault will contain approximately 11,000 sq ft of space.

John Langdon, project director for Skanska, says the vault is being built next to an existing 13-story building, which requires underpinning. “Once we are down 50 ft we have to open the wall into the existing plant,” he adds.

The current power plant is not as deep as the building foundation, so Skanska is underpinning the existing vault, using a hand-dug and concrete placement approach. The width of the site was critical in determining feasibility, and new piers would have taken too much space, Langdon says.

Skanska plans to store the large equipment and electrical gear offsite until the vault is ready. Cranes will lower the turbines, heat recovery steam generators and the other heavy pieces into place once they are brought to the site.

“The interconnection of all the electrical, mechanical and turbines is quite involved,” Langdon said.

The vault will be topped with a 2-ft-thick concrete roof and 6 ft of earth. Crews will add landscaping and reconstruct the plaza, including replacing mature trees. The university plans to work with the New York City Parks Department and the local community to design a new, inviting park space.

Simultaneous to the vault construction, Skanska will run distribution lines to each of the buildings and electrical substations to step down the voltage. Whenever possible, crews will run conduit along NYU’s existing pipes, under city streets.

Crews are working during the day and not allowed to continue operations during off hours to avoid disturbing neighboring residents. Classes in all of the adjacent buildings will continue uninterrupted, with the site barricaded for student safety. Sound attenuation equipment will keep noise from the new plant to a minimum in the area.

Kushner expects the project to wrap up in 2009.

Useful Source
New York University
http://www.nyu.edu/fcm/chp.htm

Team Box:
Owner: New York University, New York
Contractor: Skanska USA Building, New York
Engineer: Vanderweil Engineers, New York