It seems like a no-brainer, manufacturing products rather than making new ones from scratch-widely done with everything from retread tyres to refilled inkjet cartridges to remanufactured engines - should save a lot of energy, right? Not so fast, says a new study by researchers at MIT. In some cases, the conventional wisdom is indeed correct. But out of 25 case studies on products in eight categories done by a team led by Professor of Mechanical Engineering Timothy Gutowski, there were just as many cases where remanufacturing actually cost more energy as cases where it saved energy.