Electricity Load Shifted for Cost Savings

The UA's water chilling and ice storing project is reducing the amount of electricity needed to cool the campus, which is more cost-effective and environmentally conscious.
June 12, 2008
Flanked by several ice chillers, UA Senior Vice President for Business Affairs Joel D. Valdez spoke during a ceremony at the ice plant last month. Valdez said the project has captured the attention of institutions around the world.
Flanked by several ice chillers, UA Senior Vice President for Business Affairs Joel D. Valdez spoke during a ceremony at the ice plant last month. Valdez said the project has captured the attention of institutions around the world.
The newest tanks for the Thermal Ice Storage Project were added this year, bringing the UA's chilled water capacity to more than 15,000 tons. (Photo courtesy of Facilities Management)
The newest tanks for the Thermal Ice Storage Project were added this year, bringing the UA's chilled water capacity to more than 15,000 tons. (Photo courtesy of Facilities Management)
(Photo courtesy of Facilities Management)
(Photo courtesy of Facilities Management)

Can’t imagine a summer without electricity-fueled air conditioning?

The University of Arizona can – and, to an extent, does.

Besides making uncomfortable weather conditions bearable, air conditioning also is indispensable at manufacturing plants, hospitals and in other arenas.

Of course, there are drawbacks to air conditioning. Two in particular that concern the UA and its Facilities Management unit are higher utility bills, especially during the summer months, and the carbon emissions spewed by the systems.

Both are addressed by the University Thermal Ice Storage Project, an award-winning chilled water production and distribution system that spends the evening and early morning hours freezing water that is then used to cool buildings across the main campus and at the Arizona Health Sciences Center. The process moves the bulk of the UA’s electrical load from the hot daytime hours to the cooler nighttime hours.

“If we can shift some of our daytime load to nighttime, we can save $30,000 each month,” said Gordon Bush, senior staff technician at Facilities Management, the UA unit responsible for operating and maintaining University facilities.

Annual savings are expected to hit an estimated $560,000.

Also known as the "ice plant," the incentive behind the project has been to drive down the UA’s utility bill by tens of thousands of dollars monthly and to reduce the University’s greenhouse gas emissions while avoiding any disruption to daily campus activities.

“We do the cooling off-peak and reserve it. It takes less energy to accomplish the same amount of work,” Bush said.

The ice plant joins several other progressive and pioneering water practices at the UA, including waterless urinals, water harvesting and water reclamation.

The UA has two Central Heating and Refrigeration Plants. Its first, which began operations about three years ago, is near East Helen Street and North Mountain Avenue, just west of the Arizona Health Sciences Center.

“It worked so well that we expanded the project right away,” Bush said.

Last month, Facilities Management officially inaugurated the most recent ice storage project at another plant, located near the Mathematics Building.

During that ceremony, Trane awarded the UA its Energy Efficiency Leader in Education Award – the first time the award had gone to an educational institution – for being one of a few institutions to have such a project up and running. And, just recently, the UA partnered with the American Society of Heating, Refrigerating and Air-Conditioning Engineers’ Tucson chapter to begin teaching engineering students about chilled water technology and other heating and cooling processes.

Those processes involve turning off turbines that would typically help with the cooling and use the ice, as it melts, to cool buildings. This helps lower emissions, because the turbines are in use less often, and also lowers the amount of energy used during the most active parts of the day.

The system involves the use of water chillers, cooling towers, pumps and pipes that snake around the campus through underground pipes that connect the plants. The project can produce more than 900 tons of ice per hour and the pipes feed the melting ice, or cooled water, to buildings on the main campus and at the Arizona Health Sciences Center.

Because the daytime and nighttime temperatures can be so drastically different in this region, the University turns on the water chillers during the evening hours – the cooler hours – to begin producing ice. Currently, this process begins at about 7:30 p.m. and may take up to 10 hours, Bush said.

In the morning around 10 a.m., the University turns the chillers off and the ice beings to melt. It is then delivered all over campus to cool buildings, Busch said.

This process not only cools buildings, but it also used for dehumidification and also to cool equipment in research laboratories.

“It’s kind of like having a savings account,” Bush said. “You’ve got this ice already stored up and it’s sitting there ready to go when we need it."

During the ceremony last month, industry and University officials said the UA’s system is one of the most energy efficient and environmentally friendly chilled water systems in the world.

Al Tarcola, director of Facilities Management, said the ice plant project has been a “big hit.”

Officials from universities and corporations around the world have visited the UA to learn about the chilling and ice storage system and to also figure out ways they could introduce the technology back home.

“All and all, we’re on the verge of creating new kinds of technology and innovations,” said Joel Valdez, the UA’s senior vice president for business affairs.

“We don’t toot our horn too much,” Valdez added. “We have some talented individuals and we do the work we have to do and take on challenges.”