The Marcellus/Utica region has far more ethane production than we can use–even if the mighty Shell and PTT cracker plants were both in-service and operating. In fact, ethane is still (for many M-U drillers) a waste product that must be blended with natural gas or otherwise disposed of. Drillers are paying to get rid of ethane! Exporting ethane is an important way for M-U drillers to, in some cases, break even and make a profit.
