Missouri's largest electric company said Monday that it plans to invest $135 million in energy efficiency programs for customers over a three-year period.

Ameren Missouri said its costs for the energy efficiency initiative would be recouped through charges on customer bills, but it said consumers ultimately should save money because the reduced energy use would decrease the need to build expensive new power plants.

The St. Louis-based utility serves about 1.2 million electric customers, mostly in the St. Louis region or eastern and central Missouri. It already offers energy efficiency incentives to customers, which it says have totaled about $155 million since 2009.


Its proposal, which was filed Monday with the Missouri Public Service Commission, outlines an initiative that would run from 2016 through 2018. It includes incentives for retailers to increase sales of energy-efficient light bulbs and for residential customers to install high-efficiency air conditioners and appliances. Businesses also would receive incentives to implement energy-efficient measures.

Ameren's costs for the energy efficiency programs would be recouped from customers through a line-item on their monthly bills. Despite that surcharge, customers could save money in the long run because the energy efficiency steps should reduce the need for additional power generation, said Warren Wood, Ameren Missouri's s vice president of external affairs and communications.

The company plans to shut down six coal-fired generating units in the next two decades. If it weren't for energy efficiency programs, Ameren Missouri would need to build three natural-gas-fired power plants at a cost of about $1 billion each, which would be recouped from customers, Wood said.

Instead, Ameren Missouri expects to need only one of those new plants because of the energy efficiency savings, he said.

"We're seeing the ability to put off, and in some cases eliminate, the need to build the generating resources in the future, which is a savings for everybody," Wood said.