Since 1959, a single pipeline that runs overland from South Texas has supplied every last bit of the natural gas that Florida consumes. But in the American stampede for gas, that pipeline is no longer enough. Florida's appetite for natural gas is expected to double in the next eight years, with most to be used by power companies to generate electricity. Here and across the country, the shift to gas from dirtier fuels like oil and coal is widely agreed to be an environmental good.