Today in 2014, just one year ago, US Patent 8646660 B2 was issued, an invention of Thomas W. Bates, Dan Morgan, and Leslie W. Ross, for their “Reusable Beer Keg.” Here’s the Abstract:

A reusable beer keg is disclosed including a hollow beer keg body with a dispenser tube assembly having a dispenser valve, dispenser tube, and a disposable bladder. The dispenser valve is releasably attached to a top portion of the keg body and the dispenser tube and bladder extend into the interior of the keg body. When beer flows through the open dispenser valve and into the bladder, the beer causes the bladder to expand until it contacts the inside surface of the keg body. When the beer keg has been emptied it can be returned to the brewery for reuse by cleaning the dispenser valve, dispenser tube and disposing of the used bladder. The beer keg parts can then be reassembled, using a new bladder in place of the used bladder.