It is great to see testing of new technology that has the potential to be practical. Hydrogen has much better energy density than Li-Ion batteries. It remains effective in temp extremes and we know how clean it is. Although on earth it has to be cracked from water, it is the most abundant substance in the universe. Then again, it seems no source of power comes free of charge. Mining for Lithium and Cobalt as well as building batteries and generating electricity comes at a cost.
Thus far, batteries don’t seem to cut it. I know our Arrow can range about 500 miles with reserves on about 500 lbs of fuel. Batteries that permit the same performance would weight far more than the airplane itself. I think H2 has possibilities.