U.S. LNG producers are racing to add production capacity amid forecasts for strong growth in demand, with the total—concentrated in Louisiana and Texas—set to reach 10 billion cubic feet daily by the end of next year, from about 4 billion cubic feet a day today. And yet, all this capacity will not be enough to prevent the supply crunch that has been predicted by Shell. The crunch will be a result of a shortage in final investment decisions on new LNG capacity in the United States, which is shaping up as the largest emerging LNG exporter…