Wisconsin-based utility Alliant Energy has joined the ranks of U.S. utilities pledging to zero out their net carbon emissions by midcentury. The company set an “aspiration” to reach net-zero carbon by 2050 and eliminate all coal power plants from its fleet by 2040. 

Alliant’s new goal is part of a broader “accelerated sustainability” plan released this week, which includes an increase in its existing 2030 carbon-reduction goals from 40 percent to 50 percent, eliminating all coal from its generation fleet a decade ahead of the previously scheduled milestone, and boosting its 2050 carbon-reduction goals from 80 to 100 percent. 

Alliant serves about 1 million customers in Wisconsin and Iowa, and it gets about 20 percent of its generation capacity from renewables today, mostly from wind farms in Iowa. Coal made up 31 percent of its capacity as of 2018, while natural gas accounted for about 42 percent. 

Alliant joins a long list of utilities that have set 2050 net-zero carbon goals prior to being forced into them by state mandate, including Southern CompanyDuke EnergyArizona Public Service, NRG and PSEG, and, in the Midwest, Xcel Energy and Consumers Energy. Wisconsin does not have a state-level carbon-reduction mandate, but Alliant and fellow Wisconsin utility Madison Gas & Electric have set their own goals of zero carbon by 2050. 

In May, Alliant announced it would spend $900 million to buy 675 megawatts of utility-scale solar projects in Wisconsin, a significant boost above the state’s current 150 megawatts of solar capacity. The utility plans to develop 1 gigawatt of solar in the state by 2023. 

Alliant’s move into solar follows other Midwestern utilities including XcelConsumers and Nipsco augmenting wind power with increasingly low-cost solar to replace economically struggling coal plants. Alliant has retired about 1,000 megawatts of coal-fired power since 2005. 

Earlier in May, Alliant subsidiary Wisconsin Power and Light announced plans to close the remaining 380-megawatt unit of its coal-fired Edgewater Generating Station in Sheboygan by the end of 2022. Alliant has not announced a retirement date for its 1,053-megawatt Columbia Energy Center, which is its last remaining coal-fired plant in the state. 

Closing Edgewater is expected to save customers “hundreds of millions of dollars in costs,” Alliant reports. But environmental group Sierra Club has called on the utility to accelerate the retirement of its Columbia plant to 2026, saying that its Wisconsin coal fleet could cost customers hundreds of millions of dollars if left operating through 2030.

Alliant also owns capacity in six coal-fired plants in Iowa, adding up to roughly 1 gigawatt of capacity, and plans to replace much of it with natural gas in the years to come, including the 212-megawatt Burlington plant by 2021 and the 245-megawatt Prairie Creek plant by 2025. It has not announced plans to retire or switch over its 348-megawatt Ottumwa plant or its 275-megawatt Lansing plant in Iowa.