romanval writes: A coal gasification plant in Mississippi is iswitching to natural gas after 5 years of delays and $4 billion cost overrun. Megan Geuss writes via Ars Technica: "The Kemper County plant was supposed to be a cutting-edge demonstration of the power of 'clean coal,' and, despite running five years late and more than $4 billion over budget, Kemper was able to start testing its coal gasification operations late last year. The plant used a chemical process to break down lignite coal into synthesis gas, or 'syngas,' which was then fed into a generator. The syngas burns cleaner than pulverized lignite coal does. In addition, emissions were caught by a carbon capture system and delivered to a nearby oil field to help with oil extraction. That, Southern and Mississippi Power said, would reduce the greenhouse emissions of burning lignite by up to 65 percent. But with only 200 days of gasification operations under its belt, Kemper identified more issues with its technology, including design flaws that caused leaks and ash buildup."