UT Power Project Generates Savings, Ensures Reliability

By Scott Clark and Juan Ontiveros

The authors explain how improving power plant operations at the University of Texas helped the campus become more energy efficient.

Left: Scott Clark, P.E., principal, Energy & Power Solutions Group, Carter & Burgess Inc., Fort Worth; and Right: Juan Ontiveros, P.E., director, Utilities and Energy Management, University of Texas at Austin.

The power plant at The University of Texas at Austin is a model in self-sufficiency. The campus cogeneration facility supplies 13 million sq. ft. in 140 buildings with electricity, steam, compressed air, distilled water and chilled water. Every type of refined energy on campus is self-generated.

In light of a rapidly growing campus, the university wanted to ensure it had adequate, reliable and efficient energy systems for many years to come. Three years ago, it embarked on a comprehensive program to improve its power plant operations. Its goals included identifying opportunities for efficiency improvements and ensuring power reliability. With peak demand at about 60 megawatts, the plant's total electrical generating capacity of 85 megawatts was ample. However, its steam turbine generator capacity consisted of only one 25 megawatt steam turbine, installed in the 1980s, and two small, aged turbines. The campus also needed an economical backup steam turbine system to accommodate shutdowns and outages.

The university hired Carter & Burgess Inc. to conduct a feasibility study and subsequently, the design of a new steam turbine generator at the Hal C. Weaver Power Plant Complex. The firm selected a Siemens 25 MW single-extraction, full-condensing steam turbine generator.

Massive Equipment, Confined Space During the project's programming stage, consultants looked at numerous locations for the turbine/generator, which would be 32-ft. wide by 70-ft. long by 30-ft. high. The power plant complex consists of three separate buildings and adjacent areas.

With the assistance of 3-D modeling, the decision was made to locate the turbine/generator in a new addition to the existing Power Plant Expansion Building. The site's location on the front of the building provided access for equipment deliveries - an important advantage as the largest piece weighed 141 tons. Another site clincher was that installation could be executed within a non-operating power plant facility.

Coordinating the delivery and installation of 365 tons of equipment within a confined space on the core of the campus necessitated well-supervised traffic control and safety measures.

The site was also constrained by infrastructure systems. A major duct bank for electrical conduits ran underneath the turbine pedestal. To design and construct the pedestal structure, the limits of the duct bank had to be physically located. Special structural detailing was performed to account for unequal spacing between the pedestal piers.

To minimize interference with piping and structural elements, Bentley AutoPlant 3-D design software was used. Later, the 3-D model was utilized to create all of the 2-D construction documents.

Steaming Ahead to Savings In winter 2004, the turbine was in place and functioning. Based on 2004 gas prices, it was projected to save $1.5 million annually as a result of running 9.8 percent more efficiently than the existing turbine. In addition, the turbine will provide savings related to efficiencies gained during scheduled and unscheduled outages. At a total cost of $15.6 million, the project had a seven-year payback when gas prices were $4 per MMBtu. Given escalated gas prices, the payback period on the project has gone down considerably from the original feasibility study estimate.

The existing 25 megawatt turbine, in good condition, is kept on standby. Previously, when the old turbine experienced unscheduled maintenance and planned outages, the campus relied on the two small steam turbines built in the 1940s and 1950s that could incur hefty gas-usage penalties. The two older turbines were used as spinning reserve for steam in the event the 25 megawatt steam turbine tripped off line. This resulted in continuous use of low-efficiency steam generation. When the new steam turbine bypass system came on line in October, the two small turbines were completely shut down. This project will result in an additional savings of $750,000 in annual gas costs.

Complementing the new turbine was the replacement of a 1950s cooling tower with a new Marley (formerly Ceramic Cooling Tower) tower capable of running all generation equipment. Carter & Burgess supplied the engineering and architectural design services for the $8.4 million cooling enhancement project.

The new tower and turbine increased the campus's electrical capacity from 85 megawatts to 110 megawatts, giving the university the option of selling power to the grid. Given the campus's peak load of about 60 megawatts, the university could sell up to 50 megawatts. Currently, it is evaluating the possibility of selling excess power to a wholesale electric company; under certain conditions, it may be able to provide power to the grid at an economically attractive rate.