Carbon from coal plants

In his review of Earth: The Sequel—The Race to Reinvent Energy and Stop Global Warming by Fred Krupp and Miriam Horn (Physics Today, April 2009, page 63 ), Mark Ratner paraphrases from the book that a typical 500-MW coal-fired power plant “emits roughly 1 ton of carbon dioxide for every kilowatt hour of electricity,” and he adds, “Such comparisons are easy to remember.” But this one is also easy to discredit: Since CO₂ is about 25% carbon by weight, a 500-MW plant must therefore be consuming roughly 125 000 tons of coal per hour, or 3 million tons per day! The total daily coal production of the US is only 3 million tons.