A potent combination of thermal storage, a three-pronged chiller approach, and unique "trigeneration" technology contributes to the comfort of countless groups - engineers and otherwise - convening each year at Chicago's McCormick Place Exposition Center.

Anyone who has attended ARI/ASHRAE festivities at Chicago’s McCormick Place Exposition Center over the years can attest to the sheer size of the relatively new addition built a few years ago. To be exact, the annex came in at 2.2 million sq ft, bringing the center’s total area to a towering 5 million sq ft.

Efficient, Chilly Chicago

In 1992, the City of Chicago’s Metropolitan Pier and Exposition Authority (MPEA) faced the financing of a major expansion to their heating and cooling plants to accommodate such a sizable boost in square footage. Fortunately, Trigen Energy Corporation (White Plains, NY) — in partnership with the local gas distribution utility — offered a solution that would cover McCormick Place’s existing East and North Halls, the new South Hall, and the complex’s then-new Hyatt Regency Hotel as well.

Trigen designed, built, and operates a uniquely optimized chiller plant. The plant incorporates 17,000 tons of chiller capacity (using new, gas turbine-driven ammonia screw chillers, steam absorption chillers, and existing electrical centrifugal chillers). Other elements include 123,000 ton-hrs of thermal energy storage that employs the SoCool (Naperville, IL) thermal stratification fluid technology, and 338 million Btuh of boiler capacity as gas turbine heat recovery steam generators and as gas-fired boilers.

The final component was 3.3 MW of electric power generation via Trigen’s patented “trigeneration” machine, which simultaneously produces electricity, cooling, and heat from a single fuel source. Initial service began to the existing North and East Halls on schedule in 1994. Service expanded to include the new South Hall as planned in 1997. Under an amendment to the MPEA contract, the central plant also began providing service in the spring of 1998 to the 32-story, 800-room Hyatt Regency Hotel at McCormick Place. Services include the provision of chilled water for air conditioning, and hot water at multiple temperatures for space heating, domestic hot water, food service, and laundry service.

How did it turn out? Under the 29-yr energy service contract, McCormick has saved $29 million in initial capital costs, versus MPEA’s costs for self-generated cooling and heating. In addition, its ongoing O&M savings is approximately $1 million annually. In recognition of the project’s success, it earned Energy User News’ 1995 “Energy Efficient Building Award” in the thermal storage category.

Harry L. Walder, the MPEA’s senior development manager, notes, “We’re very happy with the quality of service.”

Cold Water In Kansas City

Several hundred miles southwest of the balmy shores of Lake Michigan, Kansas City was looking for a similar solution. And again, Trigen was chosen as partner for a major urban project. In this case, two miles of chilled water distribution piping was installed beneath the streets of downtown Kansas City.

This system has an installed capacity of 6,000 tons, using chilled-water supply and return temperatures of 33°F and 55°F. And as in Chicago, the SoCool approach has been in effect since early 1998, exhibiting chemical stability as well as control over corrosion over its operating life, all without any chemical additions since initial system commissioning.

The system utilizes two plants to produce chilled water. The first plant, located at the Grand Avenue Station where Trigen operates its district heating business, utilizes 6,000 tons of new, steam turbine-driven chillers operating at the reduced fluid temperature. A second plant, located in the H. Roe Bartle Conference and Convention Centers, consists of 4,200 tons of capacity leased from the city and serving the Convention Center, the adjacent Conference Center, and the Municipal Auditorium at conventional water temperatures. The two plants will eventually be linked together to incorporate a thermal storage tank at the Grand Avenue Station, allowing the production of chilled water using lower-cost, off-peak power. The stored chilled water will be used during the day as cooling peaks occur and electric costs rise. The existing 2-mile distribution system (and in future, thermal storage) utilize SoCool, allowing the water to be stored and distributed at a reduced temperature of 33°F.

Downtown Gets Upgraded

As for savings associated with this project, it is estimated that Jackson County alone has saved nearly $1 million related to the construction of its new jail annex by not having to purchase new chilling equipment or replace or retrofit its existing equipment to meet current environmental standards.

On May 4, 1998, civic leaders and members of the Kansas City business community joined with Trigen to celebrate their 20-year contract and the commencement of commercial operation of the new chilled water system serving downtown Kansas City. The new system initially supplies over 8,000 tons of cooling demand for approximately a dozen buildings in the downtown business district. There are plans to grow the system, delivering cooling services to additional building owners.