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New Efficiency Efforts Mean Economic and Energy Savings


Improvements in how UC chills water for the cooling of buildings will bring economic and energy savings, while also reducing the university’s carbon footprint.

Date: 4/20/2011 12:00:00 AM
By: M.B. Reilly
Phone: (513) 556-1824
Photos By: Joe Harrell

UC ingot   In its utility plant, the University of Cincinnati chills water and then uses that chilled water to provide cool air to campus buildings.

In February, the university made a change in the utility plant’s chilled-water system that will result in
  • A reduction of UC’s annual electricity use by 2.5 million kilowatt hours (KWh), enough electricity to power 208 homes for an entire year.
  • A reduction of 5.25 million pounds in terms of the university’s carbon footprint.
  • An increase in UC’s energy-related economic savings by $177,000 per year.

In its simplest terms, the change made to the chilled water system consisted of transitioning from a system where the water to be chilled was stored in an open basin (think of a very large and deep swimming pool) and then pumped vertically 120 feet into a cooling tower by means of electrically powered pumps.
Water cooling diagram
At left, the previous system to chill water in UC's utility plant stored the water in an open basin. The new system, depicted at right, will reduce UC's annual electricity use, reduce UC's carbon footprint and bring economic savings.



The new system consists of a closed storage tank of water to be chilled vs. the open basin. Because the tank is now closed (vs. an open basin or “swimming pool” of water) and attaches to the cooling tower via pipes that now form a completely enclosed or “closed-loop” system, the electrically powered pumps that were once needed to pump water (about 60,000 gallons per minute) vertically 120 feet to the cooling tower no longer have to do so.

Said Joe Harrell, executive director of utility services, “Now, air pressure is doing most of the work that the pumps had to do. So, now, the pumps only need to use power to move the water the last 20 feet of the chilling process. Air pressure actually moves the water for the first 100 feet.”

The project cost for implementing the closed-loop system was $847,000. But with anticipated annual economic saving of $177,000 per year in reduced electrical costs, the project will have paid for itself in almost five years.

NEW THERMAL-ENERGY STORAGE TANK COMES ON LINE IN MAY

A four-million-gallon thermal-energy storage tank, measuring about 160 feet long and placed about 30 feet below the new half field of the Sheakley Athletic Complex will come online in late May. It took 28 days to fill the tank with water in February.

The water in the tank will be chilled via electricity at night when unit costs for electricity are less expensive, and the water will be used in the heat of the day to cool campus buildings. Total cost of this project, about $5 million, will save the university between $400,000 to $500,000 per year. It’s estimated that the project will reduce UC’s electrical demand by about 4,500 kiloWatts (KW).

These most-recent efforts are a continuation of a quarter century of energy-reduction initiatives at UC. During the past 25 years, UC has consistently reduced energy consumption 3-5 percent per year. So, even as the university grew, new buildings came online and enrollment increased, the energy load was minimized, and energy costs remained flat.

UC is on track to meet the goals set out by the Ohio House of Representatives Bill 251, which passed in January 2006. It asks Ohio’s public universities to reduce energy costs by 20 percent by 2014.