Alliant, co-ops consider NG to replace canceled coal plant

The $1.3 billion power plant was slated to go online in 2013 in Marshalltown to meet the growing power appetites of customers of Alliant Energy, Central Iowa Power Cooperative and Corn Belt Power Cooperative. A group of Iowa municipal utilities was also planning to take a stake in the plant.

The recession has curbed electric demand, reducing the urgency of a new plant in Iowa. Even so, leaving the plantÂ’s 649 megawatts of power-generating capacity out of the future mix leaves a hole in projected demand that must be filled.

“Regulators and politicians have sent a pretty strong message about coal-burning power plants,” Alliant spokesman Ryan Stensland said. “But we’re still going to need more base-load generation.”

Opponents said Sutherland Unit 4 would be overly expensive and would contribute to global climate change. A hybrid plant design that allowed it to get 10 percent of its fuel from renewable biomass did not assuage critics.

One strong option appears to be a combined cycle natural gas baseload power plant, not too different from the $400 million, 550-megawatt Emery Generating Station Alliant built near Mason City in 2004. Combined cycle plants burn natural gas to power a turbine that generates electricity. The plants then recapture the waste heat from that turbine to generate additional electricity from a steam turbine.

Emery is an “intermittent load” plant. It can be activated quickly when power needs dictate, but doesn’t run all of the time like a baseload plant.

The credit rating agency Fitch said that Central Iowa Power Cooperative is working on plans to “either build or buy into a proposed combined cycle gas-fired generation project” to meet the growing energy needs of its members. CIPCO, based in rural Cedar Rapids, generates and transmits power to 12 rural electric cooperatives and 15 municipal systems.

CIPCO spokeswoman Kathe Breheny said CIPCO confirmed the utility is studying such a project, but is also weighing other options.

Alliant is also studying a combined cycle natural gas plant as one option. It would cost much less to build than Sutherland Unit 4, Stensland said, but Alliant is concerned about wild swings in natural gas prices and how they could affect electric customers.

The combined cycle gas plant could also be developed more quickly than a coal-burning plant.

“We haven’t talked specifics about any sites,” Stensland said.

He said the current site of the Sixth Street Generating Station, which was destroyed by the June 2008 flood in Cedar Rapids, hasnÂ’t been ruled out as a possibility.