CHAMPAIGN — Air-conditioning systems are on overdrive during this tropical heat wave, but the University of Illinois is taking steps to cut its electricity use.
The UI issued an “energy alert” Thursday afternoon, asking employees to conserve electricity by turning off lights, shutting down computers or unplugging appliances when not in use — especially from 2 to 6 p.m., when demand is highest.
The campus is also taking more systemic measures to cut energy use during peak daylight hours.
The National Weather Service issued its first heat warning of the year for central Illinois from Thursday afternoon through 7 p.m. Sunday. The heat index — how hot it feels, once humidity is factored in — could reach 105 to 115 degrees in the shade, and even higher in the sunshine, the weather service said.
Today was forecast to be the peak load on the regional power grid, with the highest energy consumption hour of the year, said Kent Reifsteck, campus director of utilities and energy services.
The UI produces 40 to 60 percent of its energy through the Abbott Power Plant, but it buys the rest from the grid through the Midcontinent Independent System Operators, he said.
The Midcontinent system sends out alerts to its larger participants, like the UI, when it wants users to conserve energy, he said. It has a process in place to ensure that there’s enough energy available online at the instant it’s needed, even during peak load periods, so it can meet demand and maintain reliability, he said.
‘More cost-effective' now
UI buildings are cooled through a central chilled-water system, with five “chiller plants” producing cold water that is then circulated through a system of huge pipes across campus.
The cold water goes out at about 40 degrees and is used by air-handling units in the buildings to cool the air, Reifsteck said. Instead of circulating through a condensing unit at each building, the water returns to the central plant at around 55 degrees and runs through compressors there.
On hot days, the campus shuts off some of its chillers during the day and runs them at night instead, when demand is lower and rates are cheaper.
The water chilled at night is stored in the tall water tank between Neil and Oak streets — the white one with the Illini logo — and that water is then used to cool buildings during the day while the chillers are shut off, Reifsteck said.
“That allows us to cool with the electricity we’ve consumed at night,” he said. ”It’s also more cost-effective.”
It was running at 12,000 gallons a minute on Thursday. The tank, which holds 6.5 million gallons of water, was originally intended to cool the National Petascale Supercomputing Facility, home of to the Blue Waters supercomputer, on St. Mary’s Road, but it was moved closer to the Oak Street chiller plant so it could tie into the campus system, Reifsteck said.
The plants also have several chillers driven by steam turbines, using excess steam produced by Abbott’s co-generation facilities, he said. They’re used “on days that electricity is expensive,” he said.
At the Oak Street chiller plant, a series of huge, color-coded pipes — white, blue and green — carry the chilled water and coolant in and out of various compressors and tanks stretching 25 feet high or more. The blue pipes carrying water out to campus are 54 inches in diameter, said utility foreman Jeff Davis.
The centralized system is “a lot more efficient,” he said, requiring only a few employees to operate a system cooling 130 buildings on campus.
A/C: A 'luxury' no longer
On a peak day, the UI system runs about 30,000 tons of cooling — compared to 2 to 3 tons for a typical house, Reifsteck said. One ton is equivalent to 12,000 BTUs per hour, he said.
“Air conditioning is more of a necessity than a luxury anymore. This weekend, it’s going to be tough without it,” Reifsteck said.
Campus buildings have to be kept comfortable as long as people are using them, but everyone is asked to pitch in and conserve on these unusually hot days, he said. The utilities division can also turn down some settings remotely from its control center on Oak Street.
The energy alerts have been sent out in the past to remind people to “do what we can to turn things off and conserve energy where possible,” Reifsteck said.
UI Facilities and Services also takes precautions with employees who have to work outdoors in excessive heat, said spokesman Steve Breitwieser.
The safety and compliance division has a session every spring on heat-related stress, so employees can take precautions to avoid it and know what symptoms to look for. The physical plant also keeps electrolyte replenishment packs available for employees to add to water bottles and “help keep them going in the heat,” he said.
Roofers work earlier hours during the summer months, starting at 6 a.m. from late May to early September, he said. And supervisors have discretion to adjust work hours during extreme heat, he said.