BIOGAS STORAGE BUYER'S GUIDE Double Membrane Biogas Holder: What Drives the Price, the Life, and the Quote A double membrane biogas holder stores the methane your digester makes and feeds it to the engine at a steady pressure. This guide explains the parts, the six cost drivers, and the five line items you should check before you sign. ✓ Constant pressure ✓ No steel to corrode ✓ Modular, fast install ✓ Low maintenance What a double membrane biogas holder actually is It is a