What is your opinion on using hydrogen as a power storage mechanism for renewable resources?

The current estimates for "green hydrogen" are $5/Kg.  The DOE goal is to try to get that down below $1/Kg, although it probably needs to get down to $0.50/Kg to compete effectively with natural gas.  The picture gets further complicated by location.  Rooftop solar in New England has an 11% capacity factor.  It is worse in the winter. Recently, in CT, we had night time temperatures in the single digits for several days with more forecast in the next week or two.  With daylight hours shortened due to it being winter time, sun position being low on the horizon, and partly cloudy conditions on most days, there is not enough power delivered by the solar panels to electrically heat the house 24/7 including the use of batteries.  Generating hydrogen locally will not produce enough hydrogen to get through a cold night, never mind several days of cloudy weather.  Of course, the hydrogen can be generated elsewhere and delivered to the home for energy storage at the home with sufficient capacity to overcome this, but I didn't get that impression from the brief description.

Hydrogen is being considered for energy storage for precisely the reasons that I mentioned (longer duration intermittency).  MIT studies have indicated that batteries by themselves will not likely be sufficient to handle multiple days without sunlight or wind.  They note that little or no wind can last for up to two weeks, while cloudy days can last for about 1 week.  During that time, batteries will be depleted and not able to recharge if there are no fossil fuels being used on the grid.  Current batteries can operate for up to 4 hours and are fairly expensive.  Therefore, multiple batteries would be needed along with the extra capacity needed to charge those batteries.  Fuel, on the other hand, can be generated separately and stored for long periods of time.  Thus, seasonal swings as well as shorter term needs can be addressed.  That is why storable fuels (like oil and coal) are so useful.

The other point to be made is that of costs coming down.  I am less certain of that, particularly in view of the inflation that we are now experiencing.  Of course, no one really knows what inflation will be next year or next decade.  However, raw materials costs, particularly copper and semiconductors, are going up substantially.  Shipping costs and labor costs are also increasing.  Solar panels only represent 10 - 15% of the cost of an installation.  The disinflation that we have seen for the past 40 years may, in fact, be over.  That does not bode well for the assumption that costs will continue to come down.  They might, on a relative basis, but, then again, they might not.  A lot more work needs to be done.

Hydrogen will likely have its place, but it is not the "silver bullet".  A combination of technologies including nuclear, renewables, fossil fuels with CCS, improved efficiency, batteries, and others yet to be developed will be needed.

The others who have responded so far are all correct. In addition, consider that unless the grid is saturated with renewable electricity, using generation that could be fed into the grid for hydrogen production will require fossil fueled generators to produce the shortfall. 

For energy storage, green hydrogen has a round-trip energy efficiency of about 40%. 2.5 kWh in for every kWh out. Pretty bad. Lithium-ion batteries, by contrast, can manage 90 - 95%. That's more than twice as much energy out for the same energy in. The only theoretical advantage that hydrogen can offer is the ability to expand energy storage capacity by expanding the hydrogen storage tanks. But hydrogen storage tanks are not cheap. Despite focused efforts over many years to develop something better, the best we can do is the carbon fiber-wound high pressure composite tanks that Toyota developed for their hydrogen fuel cell vehicles. With hydrogen at 2000 psi, they're able to store up to 5.5% of their mass in hydrogen. And there's no scaling advantage. So unless you're looking at some really major breakthroughs that have eluded everyone else, I'm sorry to have to advise you to forget it. Your product won't be competitive.

Sorry but I don't like Hydrogen for any use. It is expensive and dangerous. The numbers I read show it is 8 times less efficient than direct Solar PV or wind. Storing and compressing it takes a lot of energy. It can leak and explode very easily. The FOOL cell oh Fuel cells are expensive and fail if the H2 is not clean and pure. No thanks on H2.