Texas could see a 30 percent increase in greenhouse gases if all 17 of the coal-powered plants proposed for the state go online, according to a national report released by an environmental group Thursday. The report, called "Making Sense of the 'Coal Rush'" and published by Washington-based National Association of State PIRGs, says Texas' coal plants could accelerate climate change. But the company proposing the lion's share of the plants, TXU Corp., says its generators will be cleaner than any plants currently online.... Environmentalists have said the proposed Texas plants, many of which expand existing plants, will damage air quality in the Austin area... The company has committed to lowering its emissions 20 percent while doubling its coal-burning capacity.