It still requires plant vegetation
There are a couple of things wrong with the process as it is presented.
The first is that it still uses waste plant material to create acetic acid. While we have a certain amount of that already, to really create lots of hydrogen we will need to grow it. That means land and that means fresh water, neither of which we have in the quantities to replace much of the electric power we use. It's why ethanol doesn't work. But since this process produces CO2, the only way to not produce net CO2 is to capture it first with vegetation.
Also, while it's a fun science experiment to use the voltage difference between fresh and salt water, the question is why? Since it apparently doesn't need a lot of energy but just voltage, you can get the voltage from many places. You can even take some of the hydrogen output to feed a fuel cell to create the voltage. Modern power plants do that all the time. Once they're generating they use their own output to run cooling pumps, equipment, etc. Nuclear power plants even use up to 25% of their own power for operations just to keep the plant running. Mixing salty water with fresh won't work in the country's interior, and transporting hydrogen from the coasts to the interior is an unnecessary cost.
