Alliant Energy used its interruptible power program 11 times last summer versus 10 in 2011 and four in 2010. Alliant also used more of its interruptible contracts, taking about one-half of the total 260 megawatts signed up for the interruptible program offline compared to about one-quarter in 2011, according to company officials.
The interruptible power program is for large power users and is triggered by overall power load on Alliant’s system and how it affects its power reserve margin.
For residential customers, Alliant has an appliance cycling programs that remotely turns off the customer’s air conditioner or water heater for brief periods during times of peak power demand. The latter program is triggered by temperature.
Alliant Energy used appliance cycling 34 times in the summer of 2012 compared to 22 in 2011 and 7 in 2012, according to Kim King, manager of renewables and demand response programs for Alliant.
Complaints about the use of cycling and interruption were at a minimum, Alliant officials said, because the oppressive heat conditions made the need clear, and customers receive incentives to be part of the program.
“It didn’t take a genius to figure out that if we were at 100 degrees or 95 degrees, we were going to take off (power) load,” said Doug Peyton, Alliant product manager.
The most accurate measure of air conditioning demand is cooling degree days. Peyton said the summer cooling season of 2012 had two times as many cooling degree days as the 30-year average.
MidAmerican Energy spokesman Tim Grabinski said the utility had 13 large commercial interruptions and 13 air conditioner cycling events.
The number was the highest the company has had in at least five years.
Iowa’s rate-regulated utilities are required to report on their utilization of the programs every year.
The interruptible power and appliance cycling are encouraged by the Iowa Utilities Board because. They increase the reliability of the power system by reducing peak demand, reduce the number and size of costly of new power plants the utilities have to build and reduce the amount of wholesale power the utilities need to buy off the grid at peak demand periods when the prices are highest.
The cost of purchased power is passed on directly to customers, so reducing the amount of power the utility has to buy at the highest rates helps keep customer bills low.