Rick I defer to your superior knowledge regarding hydrogen bonding and likely intellect as well. My problem is I don't see that even a cell that could covert sunlight directly into hydrogen would solve the existing problem. I subscribe to the original premise in this piece that "To stop climate change, flat CO2 emissions aren't enough."
We already have a huge problem associated with heat buildup in our biosphere, mainly in the upper reaches of the tropical ocean, and this isn't going away for centuries, if not millennia.
There are only two things you can do with trapped heat; move it somewhere else or convert a portion of it to work.
Nature is moving it somewhere else, to the poles, which is and will continue to contribute to our woes.
My thesis is we can move it as well into the ocean depths, where it would have very little impact, and convert a portion of that movement into as much energy as we are currently using.
To get that energy to where it is needed would require electrolysis. To use the hydrogen the best option is probably a fuel cell and these two processes are thermodynamic mirror images only with the enthalpy and entropy signs reversed.
I fully understand OTEC is inefficient in an engineering and thermodynamic sense. The thing is that inefficiency works to our benefit because the more energy you use the more heat you have to move into the deep and to a point, you can go to far with it, this would be a good for the environment as it currently exists, IMHO.
Always interesting to hear your thoughts.