To amend the Clean Air Act to reduce emissions from electric powerplants, and for other purposes.

Clean Smokestacks Act of 2005 - Amends the Clean Air Act (CAA) to require the Administrator of the Environmental Protection Agency (EPA) to promulgate regulations to achieve specified reductions in aggregate emissions of sulfur dioxide, nitrogen oxide, carbon dioxide, and mercury from powerplants (electric generation facilities with a nameplate capacity of 15 megawatts or more that use a...