How many LV centrifuges, assuming constant full-inventory loads of rotten flesh that never run out, would need to be running simultaneously in order to make enough methane to run a 512v gas turbine constantly?
Assuming default efficiency (70% for an HV gas turbine), 1 cell worth of methane will give 31,500 EU (not sure where the different value listed in the wiki comes from), and thus run the gas turbine for about 61.5 ticks. That means it needs about 16.2 mB/t of methane to run constantly. A single LV centrifuge produces methane at an average of 1 mB every 4 ticks for most foods (the main difference is in how many food items are required, and foods that have byproducts take longer), so you'd need about 64.8 LV centrifuges.