The laws of physics prevent people from creating free energy alternatives. I have studied this GEET engine theory, the exhaust from a lawnmower is just not going to turn anything into plasma and if it did it would not create a strong enough current for electrolysis or to "crack the molecules". That guys molecules were cracked. Think about it, if plasma was splitting molecules into their component atoms why wouldn't the fuel burn up right there? why would it even make it to the combustion chamber? what will happen when you pour cold water in there?
Its a compelling theory because it is sciencey. There are plasma garbage incinerators:
https://en.wikipedia.org/wiki/Plasma_gasification
They produce little or no excess energy though and the units are massive. The advantage is they allow the incineration of hazardous and other difficult types of waste.
http://www.floridatrend.com/article/7294/incinerating-garbage-the-high-tech-way
If you want a free energy generator build a regular gasifier, you can use pretty much any dry biomass as fuel, wood or coconut husks for example. Its a tried and true technology and you can easily convert an automobile or electric generator. It's "free energy" assuming you can get wood chips or other biomass for free.
Plasma gasification
Plasma gasification is an extreme thermal process using plasma which converts organic matter into a syngas (synthesis gas) which is primarily made up of hydrogen and carbon monoxide. A plasma torch powered by an electric arc, is used to ionize gas and catalyze organic matter into syngas with slag remaining as a byproduct. It is used commercially as a form of waste treatment and has been tested for the gasification of municipal solid waste, biomass, industrial waste, hazardous waste, and solid hydrocarbons, such as coal, oil sands, petcoke and oil shale.