While an alternator may be spinning all the time, it produces significant "drag" on the engine, depending on the electrical load. So basically, it takes more fuel to turn the engine. IE, no free lunch. I would call it a "scam" because it looks like it violates a few laws of physics and chemistry.
Back in the Wright brothers day, scientists didn't think flying was impossible, of course. Neither did they think that breaking the sound barrier was impossible. Now, violating the laws of physics.. impossible.
Many experts were skeptical that flight was even possible. Admiral George Melville, the Navy's chief engineer and a president of ASME, received acclaim for his vision of converting ship propulsion from reciprocating steam engines to the newly developed turbines. When it came to the possibilities of human flight, the admiral was a skeptic who wrote with authority. He had written about flight in the December 1901 issue of North American Review that "a calm survey of natural phenomena leads the engineer to pronounce all confident prophecies for future success as wholly unwarranted, if not absurd."
In one of those delightful quirks of fate that somehow haunt the history of science, only weeks before the Wrights first flew at Kittyhawk, North Carolina, the professor of mathematics and astronomy at Johns Hopkins University, Simon Newcomb, had published an article in The Independent which showed scientifically that powered human flight was 'utterly impossible.' Powered flight, Newcomb believed, would require the discovery of some new unsuspected force in nature. Only a year earlier, Rear-Admiral George Melville, chief engineer of the US Navy, wrote in the North American Review that attempting to fly was 'absurd'. It was armed with such eminent authorities as these that Scientific American and the New York Herald scoffed at the Wrights as a pair of hoaxers.