[annie123 (OP)]

I just saw someone on a tv show who claims to have made fuel from zapping radio waves through water. If this were true surely it would be front page news but the demonstration on you tube seemed convincing. Does anyone know anything about this?

[CliffordK]

Fuel from water has been bouncing around the internet for quite some time.

In fact, you can make hydrogen and oxygen from water using electrolysis, and perhaps other methods. 

The problem is that there is always some energy loss.  So, whenever you do a two conversions (Water --> 2H₂ + O₂ --> Water), you always get back less energy than you put into the system.

Hydrogen gas is used for a number of processes, and can be made through some form of electrolysis, or through conversion of fossil fuels.

One of the reasons that fossil fuels are popular for propelling vehicles is that refuelling is relatively quick, and it has a higher energy density than batteries, for example. 

Liquid, or high pressure hydrogen could also be used similarly with potentially a rapid refuelling process and high energy density.  So, one could potentially use any energy source to create hydrogen for use as a fuel.  Solar, nuclear, whatever.  There may be some safety issues with the fuelling process as well as the transport of hydrogen that may limit the automotive applications.

But, alas, one still needs to add energy.  Any system claiming to create free energy from water is a scam.

[peppercorn]

Traditionally 'fuel' was a combustible energy source that natural processes stored up for us.  Making, rather than mining/collecting 'fuel' should be a phrase limited to processes that 'upgrade' a natural fuel in some way (like making Liquid H2 for rocket engines [as energy-per-Kg is king when launching a rocket], say from Natural Gas).

The topic title/description inadvertently leaves out how the electricity (to power the radio-wave generator) will require considerably more energy than can ever be returned in consuming any resultant 'fuel' (certainly hydrogen unless other compounds are involved). 
Because the quantities of free hydrogen (ie. not already reacted) on Earth are trace, it might be better if hydrogen as a power provider was always labelled as a (gaseous) battery (as should Aluminium, Zinc, etc).

If the producers of the TV program are labelling the process of splitting water with EM radiation as 'fuel' I'd say they are only fuelling the flames of pseudoscience.

[syhprum]

There are only two ways you can obtain energy from water either by its thermal potential or its grvitational potential.
If you had a large tank of water sitting on the top of your car it could drive a turbine at road level although the power avaiable would be tiny.
Also if the temperature of the water was above ambient it could drive some kind of heat engine although yet again the power would be tiny.

[syhprum]

Could Hydrogen be considered a fuel in its own right ? surely energy can only be derived from it if there is Oxygen of Flourine or some other element with which it can combine.
One often reads of "mining other planets for Hydrogen" as rocket fuel but it is no use without an oxydant!.