West Alton - Ameren.com

West Alton Energy Center

The West Alton Energy Center is a planned natural gas power plant designed to provide reliable, around-the-clock baseload power for customers while keeping costs as low as possible, supporting economic development in the region and strengthening the company’s balanced mix of energy. Pending regulatory approval, the 2,100 megawatt (MW) facility is expected to begin operating in 2031.

About the West Alton Energy Center

Most people don't spend much time thinking about where their electricity comes from until they need it. Whether it's keeping a home comfortable during extreme temperatures, running a business, charging devices or caring for family members, reliable electricity matters every day.

Customer needs don't stop when the sun sets or the wind dies down. West Alton would fill those gaps with steady, dependable power. It would work alongside Ameren Missouri's existing and planned resources, including solar and wind, along with nuclear, coal, hydro and battery storage, so each one does what it does best.

Adding 2,100 MW of always-on generation will further improve reliability and contribute to Ameren Missouri’s balanced generation mix, which is designed to optimize costs over the long term. The West Alton Energy Center will also strengthen Missouri's energy security by supplying dependable, in-state generation to serve homes, businesses and growing communities across the state.

Why not keep operating the Sioux Energy Center? While Sioux has served customers for more than six decades, it cannot run forever. Planning now helps keep power reliable as Sioux nears the end of its useful life. Building West Alton nearby would also make use of existing land and infrastructure.

Project Benefits

Delivers electricity day and night as customer needs change

Adds more Missouri-based generation, reducing reliance on outside markets when prices climb

Supports Ameren Missouri’s broad mix of energy by providing steady output when other resources may not be producing.

Protecting Existing Customers

State law and the company's Powering Missouri Growth Plan include provisions to make sure data centers contribute to the costs of the infrastructure needed to serve them, protecting existing customers while providing reliable service for all. Among those provisions, data centers are required to pay 100% of the upfront costs associated with connecting to the energy grid.

Building a power plant takes years, and how it is financed affects the amount of financing costs reflected in customer rates over time. When every cost is borrowed and repaid only after construction ends, interest continues to accumulate and increases the final price. Covering some costs during construction instead of waiting until the end is one way to bring that total down.

This financing approach is called Construction Work in Progress, or CWIP, and it is allowed under Missouri law. As part of this filing as required by applicable law, Ameren Missouri asked the Missouri Public Service Commission to identify which project costs could qualify. In 2024, a State of Missouri analysis found that similar financing approaches reduced total project costs by millions of dollars, illustrating how lower financing costs can produce meaningful long-term savings.

In 2024, a State of Missouri analysis found that similar financing approaches reduced total project costs by millions of dollars, illustrating how lower financing costs can produce meaningful long-term savings.

Customer Protections

Missouri Public Service Commission approval required
Construction progress reviewed during the project
Refunds can be required if approved conditions are not met

Will customers pay for West Alton?

West Alton will not change customer bills today. The project is not part of Ameren Missouri's current rate review. If the project is approved, customers would pay only the costs the Missouri Public Service Commission approves through a public process, including any CWIP-eligible costs. The exact cost is subject to a procurement process and it would be inappropriate to discuss at the stage of the filing because it might impact the costs we do experience. New large energy users, such as data centers, must pay their fair share of the costs to serve them, including an appropriate share of generation costs.

How could this approach lower costs?

Large energy centers take years to build. If every cost is borrowed and repaid only after the plant opens, interest accrues the whole time and increases the total cost. Covering some costs earlier reduces that interest and lowers the overall amount customers pay.

Would this change my bill today?

No. This financing approach does not change bills now. Any future costs would still need Commission approval through a public process before they could appear in rates.

Who decides what customers pay?

The Missouri Public Service Commission, following a public process, makes that determination. Ameren Missouri proposed the project, but the Commission decides which costs are prudent and can be recovered. The Commission could require refunds if any financing costs associated with imprudent expenses are reflected in rates.

Costs tied to a project like the West Alton Energy Center are not added to bills automatically. Any changes would first need review and approval by the Missouri Public Service Commission through a public process. Over the years it takes to build a project of this size, system costs can shift as the grid is maintained and improved.

Several important points remain unchanged.

Costs are not included in rates unless the Commission approves them first.
Regulators decide what costs can be included in rates before customers are charged.
Large new energy users are required to pay their share of the infrastructure built to serve them, which can help hold down costs for other customers.

Will this project increase my bill?

System costs can change over time as the grid is maintained and improved. Any changes tied to a project like this would need review and approval by the Missouri Public Service Commission before taking effect.

Why not wait and add all costs after the plant is complete?

Waiting until the project is complete typically means more borrowing over a longer period. That increases financing costs, which customers ultimately pay. Spreading some costs during construction can reduce those financing costs and lower total costs over the life of the project, while maintaining reliability.

Could large energy users increase costs for other customers?

Missouri law and Ameren Missouri's Powering Missouri Growth Plan include provisions to make sure data centers cover costs of the infrastructure needed to serve them, protecting existing customers while providing reliable service for all.

Why not just buy more power from the market?

Adding Missouri-based generation provides another dependable source of power that can be available when customer needs are high and market conditions are changing.

There is strict environmental oversight for the proposed energy center. The West Alton Energy Center must meet all state and federal requirements for protecting air, water and Missouri communities.

Modern combined-cycle natural gas facilities are among the most efficient power plants available today, producing lower emissions than older fossil-fuel generation while providing dependable electricity that supports grid reliability and complements renewable energy resources.

Emissions from Ameren Missouri's generation fleet have dropped sharply since 2005:

CO₂ emissions are down about half.
NO_x emissions are down about two-thirds and 79% below EPA standards.
SO₂ emissions are down more than 75% and 82% below EPA standards.
Mercury emissions are down more than 93% and are 33% below EPA standards.

Supporting Missouri's Economy

Expected to create more than 1,000 construction jobs over several years of building

Anticipated to host approximately 45 permanent jobs focused on safe, reliable energy center operations once complete

Locating next to the existing Sioux Energy Center means maximizing existing resources and delivering more value for customers

Supports local and regional suppliers and the broader economy

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