SOUTH African natural gas and helium producer Renergen will start production of its helium powered ultra-cold mobile freezer in the next few days and has started discussions to sell the units to logistics companies, it said yesterday. Companies and governments around the world are working on ways to establish cold-chain storage and delivery systems for vaccines such as the Pfizer Inc and BioNTech shot, which must be shipped and stored at ultra-cold temperatures and can only last at standard fridge temperatures for up to five days. As a solution, Renergen on Monday launched its prototype cold-chain storage called Cryo-Vacc, which…