Is there any 72 hours exemption visa bags storage at Beijing Capital Airport?

Travel with Air China from Bangkok and plan to stay in PEK for 4 days 3 nights. Take advantage of 72 hrs visa exemption before flying back to Calgary. Wondering is there any storage for my extra bags that I don't need to carry with me in town. I have heard the rumors that there is free for 72 hrs lay over. Is it true? Thanks