That’s according to Thames Water, which says the congealed mass of fat, oil, grease, wet wipes and sanitary products in Whitechapel will create enough green energy to power 350 double-decker buses for a day.
Around a third of the 130-tonne fatberg has already been removed, with work now predicted to extend until October.
The fatberg is being broken up with high power hoses and its oil and fats are being converted into the biofuel to provide a cleaner-burning, lower emission replacement for diesel.
The solid, unflushable parts of the blockage will be disposed of.
Thames Water Waste Network Manager Alex Saunders said: “It may be a monster but the Whitechapel fatberg deserves a second chance.
“We’ve therefore teamed up with leading waste to power firm Argent Energy to transform what was once an evil, gut-wrenching, rancid blob into pure green fuel.”