Public utility company

Ameren

(AEE) - Get Report

said Tuesday, that it signed an agreement with

Hitachi Power Systems America

, a wholly owned subsidiary of

Hitachi America

, to design and supply scrubbers at three of its coal-fired plants to help reduce sulfur dioxide emissions.

The financial terms of the deal were not disclosed.

The scrubber projects are planned for AmerenUE's Sioux plant in St. Charles County, Mo., and at two Illinois plants - Ameren Energy Resources Generating company's Duck Creek Plant and Ameren Energy Generating company's Coffeen Plant.

A total of five scrubbers will be installed at the three facilities - two scrubbers at Sioux, two at Coffeen and one at Duck Creek. Timing of installation is under review, the company said.

Earlier, on Aug. 2, Ameren announced that its Illinois-based generating subsidiaries and the administration of Illinois Governor Rod Blagojevich had reached an agreement to significantly reduce mercury emissions beginning in 2009, nitrogen oxide emissions by 2012 and sulfur dioxide emissions by 2015. The multi-pollutant emission reduction proposal is now subject to approval by the Illinois Pollution Control Board.

The clean air interstate rule, which became law in 2005, requires significant further reductions in sulfur dioxide and nitrogen oxide emissions. The clean air mercury rule establishes the first requirements for mercury reductions.

In order to meet the new regulations, Ameren expects to incur a cost of $2.7 billion to $3.4 billion over the next 11 years.

This story was created through a joint venture between TheStreet.com and IRIS.