Today, the Union of Concerned Scientists (UCS) released the findings of an economic analysis indicating as much as 18 percent of the country's coal-fired energy generating capacity should be considered for closure. The study found as many as 353 generators in 31 states, totaling 59 gigawatts (GW) of electricity generation capacity, likely will be more expensive to operate after installing modern pollution control equipment than switching to cleaner energy alternatives such as natural gas, renewable energy, or using greater energy efficiency measures. These potential closures are in addition to 41 GW of already announced coal retirements.