A promising development in fuel cell technology for electric cars. This could also reduce the need for large batteries.
Not promising, unfortunately the limiting factor with hydrogen is procuring pure hydrogen. Earth has lots of hydrogen, but it is not atomic hydrogen needed by fuel cells. Rather, the hydrogen on Earth is in compounds such as water and oil, and making pure hydrogen from a compound such as water is expensive (uses much more energy than produced by the atomic hydrogen) or such as oil is dirty (releases CO and CO2). These are physical limits, not process limits and can never be overcome.
A problem with renewable energy sources like wind and solar is that a wind or solar farm might have a rated capacity of many megawatts, but there is no guarantee that times of demand will exactly coincide with times of supply.
Hydrogen is easily produced by the hydrolysis of water, and could be achieved cheaply by using this spare capacity whenever it occurs. Thus all electrical energy companies could improve profitability by setting up hydrogen production facilities.
The last bastion of making oil obsolete, maybe? Exciting!