There have been some studies that say we've got a couple of hundred years' worth of coal. why not coal instead of natural gas? >> well, the environmental concerns about co2, the study we wookd looked at was natural gas in a carbon strained environment. when you compare gas to coal, you get the carbon benefits. we looked very specifically at the opportunities for increase gas demand and the two areas where we saw the greatest opportunity for increased use of gas was in power generation, currently 51% of our power generation is from coal and 21% is from gas. and the other opportunity space for i...