Dow Chemical Co. will increase its ethylene and propylene production to cash in on higher U.S. natural gas production from shale, according to the Associated Press. The chemical company said it plans to build a new ethylene plant on the U.S. Gulf Coast that will be operational by 2017. It also plans to restart its ethylene plant near Hahnville, La., by the end of 2012. Dow also plans to build a new propylene production plant in Texas, slated to be operational by 2015. Propylene and ethylene are chemicals used in a variety of industrial processes.