Iowa’s wind, which last year became the state’s largest source of electrical power, has reached something of a tipping point, energy leaders say.
“Wind and solar are the economic choices,” said James McCalley, distinguished professor of electrical and computer engineering and the Jack London Chair in power systems engineering at Iowa State University. “It’s no longer about being green. It’s an economic choice if you’re building at utility scale. Even five years ago, we weren’t able to say that.”
Wind turbines supplied 42% of the electricity generated in Iowa in 2019, or more than 10,000 megawatts (MW) worth, according to the federal Energy Information Administration (EIA). That’s the highest proportion of any state, and helped push wind’s share in Iowa past that of coal-fired plants for the first time. The state remains the third-largest wind energy producer, on a total MW basis, after Texas and Oklahoma.
The American Wind Energy Association says the $19 billion invested in Iowa wind power over the past few decades has created more than 9,000 jobs in the state.
Government support and subsidies for wind power are now ending, Mr. McCalley said – not out of political opposition, but because they’re simply no longer needed. With the infrastructure in place, wind’s marginal cost – the expense of adding additional generating capacity – is “close to zero.”
“What does it cost you to generate one more megawatt hour?” he said. “For coal and gas, you have to buy that fuel and build that plant. For wind it’s almost nothing. You build a lot of wind capacity and it pulls down that marginal cost pretty effectively.”
Iowa’s utilities are responding rapidly to the changing economics of wind. Alliant Energy last week unveiled its Clean Energy Blueprint for Iowa, “a path for accelerating their transition to cleaner energy for customers.” The plan will add 400 MW of solar-generated power over the next three years, supplementing the 1,300 MW already generated by Alliant-owned wind farms. That will bring renewables’ share of Alliant’s portfolio to about 50%.
Under the plan, Alliant’s coal-fired plant at Lansing in northeast Iowa will also be shut down by 2022, and its Burlington plant will shift from coal to natural gas next year. The changes will result in the loss of about 38 jobs between the two facilities, but should help avoid $300 million in costs over 35 years, according to the company.
“We don’t have to make those [plant] upgrades and the operating and maintenance costs,” said Alliant spokesman Mike Wagner. “It’s money we don’t have to spend, and throughout the company we’re focusing on reducing costs to the customers so we can stay out of rate [increase] cases.”
Improved battery technology is playing a big role in plans to further shift to wind and solar power. On Oct. 21, Alliant began drawing from a 2.5-MW solar array in Marshalltown, backed by battery storage that captures the energy produced by solar arrays during the day, for use at lower-demand times in the evening.
“We are exploring battery storage as a cost-effective alternative that meets our customer’s energy needs while also creating a connected energy network that fully realizes the value of combining these resources,” said Terry Kouba, president of Alliant Energy’s Iowa energy company.
At MidAmerican Energy, “we expect to top 80% [renewable sources] by the end of this year,” spokesman Geoff Greenwood said. “We’re considered the top state-regulated utility in wind generation in the nation.”
MidAmerican maintains more than 3,300 wind turbines at 36 Iowa sites. Its Diamond Trail wind farm in western Iowa County is scheduled to begin generating 252.5 MW from 77 turbines by the end of the year.
The company is working with the manufacturer to determine the cause of four wind blades damaged since last October. Most of the 46 turbines idled Oct. 15 after a blade broke off a tower in Greene County have since returned to service, Mr. Greenwood said. Lightning strikes may have contributed to the failures, which affect only turbines supplied by Vestas Wind Systems, a Danish company.
“Wind turbines are engineered to withstand the kinds of weather we have here,” Mr. Greenwood said. He noted MidAmerican’s wind turbines weathered the Aug. 10 derecho with only minimal damage.
The plans of the state’s two largest utilities should further reduce Iowa energy costs, which are already below the national median, in the years to come.
“In 10, 20 years we’re going to see the prices of overall energy way, way down,” Mr. McCalley said. He estimated costs may drop to $5 to $10 per megawatt-hour, compared to more than $30 for a coal-fired plant.
Getting that cheap power to consumers from wind farms, located mostly in north-central and northwest Iowa, is the harder part, however. That challenge is driving the planning and construction of transmission lines in the state and beyond.
“We certainly have the transmission today to serve the existing wind resources,” Mr. McCalley said. “As we continue to grow this wind resource, there’s no doubt the transmission system has to expand with it.”
High-voltage transmission lines in Iowa are owned by MidAmerican Energy and ITC Midwest. About 54% of the power conveyed over ITC’s lines is wind-generated, up from 16% in 2007 when the company purchased the system, according to Dusky Terry, president of the Cedar Rapids-based company.
ITC, which operates about 6,700 miles of transmission lines in Iowa, Minnesota, Illinois and Missouri, has added more than 230 miles of new line since 2018. Work is scheduled to begin next year on the Cardinal-Hickory Creek line, running about 100 miles from a substation northeast of Dyersville, across the Mississippi River to just west of Madison, Wisconsin.
“We’ve seen a significant increase in wind energy capacity,” said Mr. Terry. “That’s been a driver.”
ITC has added 31 new generator interconnections to its system since 2007. Each interconnection links a wind farm of 40 to 50 turbines to the regional grid. Since 2008, the company has added about 3,700 MW of wind-produced electrical capacity, enough to power 2.6 million homes.
“It’s a lower-cost generation source, but it also requires a new transmission system,” Mr. Terry said. “You need multiple transmission lines to connect all those wind farms, and some natural gas plants.”
Power generated by wind in Iowa mostly goes east, Mr. McCalley noted.
“We’re all about moving power eastward,” he said. “Iowa happens to be one of those really good wind states, and of the really good wind states it’s probably the most eastward of them. It’s captured just the right balance between proximity [to consumers] and the wind.”
Coal-fired plants generated about 35% of the state’s electricity last year, down from 59% in 2014, according to EIA. Natural gas contributed 13%, a record high. Nuclear power provided 8% of the state’s mix, a number that will drop with the decommissioning of the Duane Arnold Energy Center near Palo. The planned shutdown of Duane Arnold, the fourth-smallest nuclear plant in the country at 601 MW, was moved up to August after it sustained extensive damage to its cooling towers during the derecho.
