Felt like this compliments the Practical Engineering video from yesterday by showing that RO has its own difficulties beyond the cost and energy usage. I've heard about these brine disposal issues, especially for the huge coastal cities. Personally, I am of the mind that municipal water demand, ecology, and fisheries all have higher stakes in coastal water quality than the energy industry (green or not).
Second to that, I don't know much about Hydrogen energy, but I had the understanding that electrolysis of water was net negative energy. I'm not sure if that was already counting RO treatment (figure it is cleaner with DI water), but if it wasn't then that makes it even more of an energy loss. I'm often making the argument that transitional energy, from fossil fuels to renewable, is going to be a mishmash of half-working parts and deviation from the efficiency that we enjoy with a mature fossil fuels industry. I don't think that's an excuse to trip over ourselves and do a lot of the same things that oil companies did (destruction of entire ecosystems, getting in the way of the needs of residents, profiting from the results of public capital investment).