Snake oil Energy.

The myth being perpetrated by snake oil energy salesmen is that hydrogen Hyper cars using fuel cells could establish a system of distributed power generation that would eliminate the need for coal burning or nuclear power plants.

Under this hypothesis, hydrogen produced from electricity using electrolysis would be used to power cars that, when not in use, would be plugged into the home to provide electricity for the home; electricity generated by the fuel cell and not needed by the home would be transferred to the grid for everyone to use, presumably to produce hydrogen for other Hyper cars to perpetuate the cycle.

This slight of hand gives the appearance of an endless supply of hydrogen and electricity from the Hyper car that eliminates the need for central power plants.
The concept is akin to the perpetual motion machine. Simple logic as well as the laws of thermodynamics show why the concept is snake oil energy.
Producing hydrogen incurs losses so that, at best, only 80% of the energy from the electricity in the electrolysis process is converted to hydrogen. Converting the hydrogen to electricity in the fuel cell produces additional losses where, at best, only 80% of the energy from the hydrogen is converted to electricity; to power the electric motors driving the car or to provide electricity for the home or grid. (Today, both these processes are closer to 50% rather than 80% efficient.)
If, for example, a Hyper car was plugged into the home and produced its hydrogen from the electricity it produced for the home, with no external energy inputs, the system would quickly grind to a halt.

The only conceivable way for such a system to work is to use natural gas with steam reforming to produce the hydrogen that drives the fuel cell that produces electricity for the car, home and grid. But natural gas is beginning to be in short supply so a system of distributed energy using Hyper cars with hydrogen produced from natural gas does little to solve the nation’s energy problem; and probably exacerbates it.

Hydrogen is very possibly the best long term solution to America’s quest for energy independence; very possibly coupled with nuclear power for producing hydrogen by either electrolysis or a thermo chemical process.
Hyper cars and distributed generation are Snake oil Energy.