He skipped the best and most cost effective way to do so. Nuclear power.
In addition, generating hydrogen would potentially be a way to make non-competitive and unreliable sources such as wind and solar profitable. Instead of burdening the power grid with their overpriced electrons, why not convert those electrons into hydrogen? They can produce when the sun shines or the wind blows.
Why not, asks King, just run a vehicle on natural gas to begin with?
Because natural gas has other far more productive uses than transportation. Home heating, industrial furnaces and metal making, fertilizer and chemical processes etc. Use too much for cars and you drive the price high for other uses where there is no practicable substitute for natural gas.
There is still a lot of development necessary before we get to a hydrogen economy, but to my knowledge, there are no fundamental technical or economic roadblocks.
Except that the current hybrid cars are already on the market and we already have a fuel distribution system for them.