Dr. Robert Williams, a senior energy scientist at Princeton, agrees."At the oil prices that we expect for the long-term, it would be economic," Williams said.Stahl told Williams about the jar of diesel Schweitzer showed her. Is this synthetic fuel going to be that clean and smell that good?"Oh, yes. The Fischer-Tropsch diesel is a superb fuel," said Williams. "Not only is [it] cleaner than conventional diesel, but it also leads to improved engine performance."And he explained why the process works environmentally.