Ameren has joined the ranks of U.S. utilities pledging to reach net-zero carbon emissions by 2050, with a long-range plan that invests nearly $8 billion in renewable energy and accelerates some coal plant closures — although it will retain much of its coal fleet through the next two decades. 

Like other net-zero carbon goals, Ameren’s will rely on “further advancements in innovative, carbon-free technologies and constructive federal and state energy and economic policies” to reach its final goal, CEO Warner Baxter said in a Monday statement. 

Ameren joins a growing list of U.S. utilities committing to net-zero carbon by midcentury in states that haven’t yet set that goal as a mandate, although several are on the cusp of doing so. The list includes Duke Energy, Dominion Energy, Southern Company, Arizona Public Service, NRG, PSEG, Xcel Energy, Consumers Energy, Alliant Energy and, just last week, Entergy. 

In its 15-year integrated resource plan (IRP) released Monday for review by Missouri regulators, the utility serving about 2.4 million customers in Missouri and Illinois plans to invest nearly $8 billion to add 3.1 gigawatts of renewables to its generation mix by 2030, hitting a total of 5.4 GW by 2040. That will allow it to reduce carbon emissions by 50 percent from 2005 levels by 2030 and by 85 percent by 2040, accelerating by a decade its previous plan to cut carbon emissions 80 percent by 2050. 

Ameren Missouri’s 10.1 GW of generating capacity, measured in terms of 2020 peak summer demand, incudes 5.3 GW of coal, 2.8 GW of natural gas, 1.2 GW of nuclear, 820 megawatts of hydroelectric and 13 MW of solar. Ameren Illinois doesn’t own generation; it acquires generation resources through a procurement process managed by the Illinois Power Agency or through retail electric suppliers. 

The new IRP and zero-carbon goals accelerate the growth of renewables called for in a Smart Energy Plan the utility filed with Missouri regulators in February. That includes spending about $1.2 billion to acquire two Missouri wind projects with 700 MW of generation capacity expected to be complete by this year and in service in early 2021. Ameren Missouri has also initiated a request for proposals to solicit bids for wind and solar projects; it plans to create a renewable subscription program to expand on existing subscriber and community solar programs. With these avenues for renewables growth, Ameren expects to add about 1.2 GW of solar, 300 megawatts of wind and 900 megawatts of a combination of those two resources by 2030, as this timeline from its IRP indicates.

Coal and natural gas remain for decades 

The timeline for coal plant retirements has also been accelerated for its Sioux Energy Center coal plant, now expected to close by 2028, and its Rush Island Energy Center, which will shutter by 2039. Ameren already planned to close its Meramec Energy Center coal plant by 2022 and two units of its four-unit Labadie Energy Center plant by 2036, removing three-quarters of its coal-fired energy generating capacity by 2040. All remaining coal-fired plants are scheduled to retire by 2042. 

Replacing the round-the-clock capacity provided by its coal plants will require investments in energy storage as well as policies to promote the efficient use of customer-owned distributed energy resources including rooftop solar, electric vehicles and electrification of building heating loads, the IRP states. 

Ameren has asked Missouri regulators to approve $68 million for three solar-battery pilot projects, each linking 10 MW of PV to several hours' worth of battery storage for communities served by single transmission lines that can experience long power outages. Its IRP identifies lithium-ion battery batteries as a “major supply-side candidate,” but it is also examining the potential for vanadium redox flow batteries and has identified a potential site for a new 600 MW pumped hydro plant.

Ameren will also continue to explore new combined-cycle natural-gas power plants to meet its reliability needs, leaving its IRP open to critique from clean-energy and environmental groups that have questioned the wisdom of investing in resources that emit carbon and may be left as stranded assets by falling costs for renewable energy paired with energy storage. 

Uncertainties around state policy and future technological developments

Missouri lacks the aggressive 100 percent carbon-reduction goals of states including Hawaii, California, New York, Virginia, Colorado, New Mexico, Nevada and Washington state, with a Republican-controlled state legislature that’s been unwilling to push beyond its existing renewable portfolio standard of 15 percent by 2021. But like other utilities that are leapfrogging state policies, Ameren is facing increasing demand from customers for clean-energy options and from investors to reduce its reliance on carbon-emitting generation that contributes to global warming. 

Ameren serves about 1.2 million customers in the southern parts of Illinois, where efforts to adopt a 100 percent carbon-free energy policy have been stymied by the long-running conflict over how to manage nuclear power plant subsidies for Exelon, which owns Chicago-area utility Commonwealth Edison. A bribery scandal for which ComEd has paid a $200 million fine has undermined Exelon’s plans for an energy bill that would boost its nuclear fleet’s financial prospects, and Exelon is threatening to close two nuclear plants if it doesn’t receive state relief. 

Ameren is lobbying for a bill in the Illinois legislature, dubbed the Downstate Clean Energy Affordability Act, that would boost the state’s renewable portfolio standard and increase investment in solar energy, transportation electrification and battery storage. It’s unclear how the bill, which applies only to Ameren’s service territory, will fare amid efforts to align the state’s stalled energy legislation with a clean energy plan released by Governor JB Pritzker last month. 

Ashok Gupta, a senior energy economist with the Natural Resources Defense Council, said in a prepared statement that Ameren’s new net-zero carbon goal is “huge progress from where the company was just three years ago.” Beyond clean-energy growth, the utility's plan for increasing demand response and energy efficiency could result in savings that equate to two large power plants, he noted. 

But improved state and federal policy support will be critical for driving increased carbon reductions and economic benefits, Gupta said. And as with all U.S. utilities contemplating complete decarbonization, Ameren will rely on a host of new technologies becoming cost-effective over the next 30 years. Ameren Missouri’s IRP cites “carbon capture and sequestration, hydrogen fuel for electric production and energy storage, next-generation nuclear, and large-scale, long-cycle battery energy storage” as key components of that future technology mix.