Today in 2011, US Patent 20110017737 A1 was issued, an invention of William P. Apps, for his “Plastic Beer Keg.” Here’s the Abstract:
A plastic beer keg includes an outer container and an inner liner. A removable lid is secured over an opening to the container to enclose the liner. The liner includes a neck portion and a body portion. A head contact member transfers axial forces imparted by handling equipment away from the neck portion.
From reading through the description, the idea of this invention is to replace the costlier metal kegs currently in use today. Only time will tell.