Solar Energy cannot be Alternative Eneregy
We frequently discuss the average value, however, it is dangerous in solar energy. For example, an example below shows average sunshine to be 4 hours/day but we meet 4 days of 0 sunshine. In this case, we have to store the solar energy for 4 days.
The battery for 4 days is 11 billion kWh and hardly realized.
Hydrogen, Storage Problem
Energy volume density of hydrogen is extremely smaller by an order of magnitude than gasoline even at high pressure. This means it needs 10 time larger volume to transport. At 700 atmospheric pressure, 7000 tonnes is imposed on 1 m2 surface, then it is impossible to make a large container. Including the weight of container, Energy density /kg becomes extremely large.
Storing liquid hydrogen needs -253 degree, electric power for this purpose becomes enormous. In order to avoid, thick heat insulation wall is required. If the tank is fully filled, it might be better but small amount remained in the tank should be serious problem because heat income from the wall stays the same but heat receiving hydrogen volume becomes small.
Getting hydrogen from methane etc. emits CO2.