If you pump up the hill, say to 3000PSI, then waste pressure on the way down: you lose said wasted energy. Pumped Hydrogen Storage requires maintaining full pr

If you pump up the hill, say to 3000PSI, then waste pressure on the way down: you lose said wasted energy. Pumped Hydrogen Storage requires maintaining full pressure across the entire pipe. Which should be reasonable: the "fill up" pipe already needs to go from the bottom to top at full pressure. Reversing the flow should be enough. The issue would be if the fill method was staged pumps.