I used this idea for the Purifier in Tier 3...where the process uses Oxygen. Tier4 [Chem Injection Chamber] process requires HCl. Converting Brine to HCl requires you to use 2 different separators during the process and you cannot use this method to power either of them. Brine is NaCl. You need a separator to get the Chlorine [Cl] with Sodium [Na] as a waste product. The NaCl separator cannot power itself. Then you need to combine the Chlorine with Hydrogen. That's another separator that can't power itself, as you're using the Hydrogen in the Chem Infuser to produce the HCl. If you want to run the line at max speed [enough HCl in a fully-upgraded Adv Factory Injecting processing 5 items at once], you'll end up having 15 separators that you'll need to provide power for.Gas burning generators produce 800 RF/t and use half of the Hydrogen the seperator produces. So 2 gas burning gens with a separator will be selfsustaining and produce O2 for free. Need more O2, just make another 2 gens and 1 seperator. piece of cake.
The idea of self-sustaining or energy-positive separators would only work if the water separation produced an excess of Hydrogen [so you could run the 2 Gas gens and have some Hydrogen left over]. Currently, water separation is break-even when using Hydrogen in two Gas gens. No excess Hydrogen is produced. I also looked into perhaps using Ethylene as the Gas gen fuel, and it may work out [even though the process to make Ethylene requires Hydrogen]...but with Wind Turbines what's the point?
Mekanism mod author made Tiers 4 and 5 very difficult to sustain production due to bottlenecks with the required catalyst production and power consumption/delivery. I'm sure it's possible but way to complex to be worth building in survival [IMO].