It could be possible to get the Oxgen an Hydrogen from sources other than water, some sort of metastable source(s). Then it is possible to get more energy out than you put in even with inefficiency because, for your part, it's not a full cycle. The same is the case for petroleum. It doesn't take more energy the drill, pump, refine, and transport it than we get by burning it.

What everyone is ignoring here, including the linked article, is that Physicists and Mathematicians in Newton's era were REQUIRED to be ordained Ministers in the Church of England. This decree was set forth by King Charles II.

The political climate closely tied Religion and Science. (quite evident in the strong tie between Trinity College and the Royal Society) That way they resolved all of the Galileo type problems. Newton disagreed with much of the church's teachings, and refused to be ordained. Thus he had to obtain special permission from the King. By keeping his disidence in his private notebooks, he could continue his scientific/mathematical endevours.