Power From Freshwater-Saltwater EcoSystems
Freshwater and saltwater boundaries contain vast amounts of energy. The electric energy generated by these estuaries could be used to meet the ever-increasing demands of many consumers. Essentially you will be using the saltwater gradient present across river-ocean junctions to produce power.
The electrochemical gradient caused by freshwater and saltwater junction can function as a battery. Sample tests by researchers have shown that these junctions can provide up to 0.4W per square meter. Although dirty water could play spoilsport by blocking the membrane.
Hitherto, other ways of producing electricity, through salt water gradients, had many drawbacks and failed to be a viable form of renewable energy. Osmotic processes were hampered by bad micro organisms which blocked the membranes and sabotaged it. Other methods had lower throughput. One such method was exposing the electrodes to different salt concentrations, the amount of power generated was puny. Another method using reverse osmosis had the foul water drawback, wherein the membrane is totally blocked because of bad micro-organisms. Yet another method was to tap into the potential across the ion-exchange membrane, but again the joules obtained was insignificant. Osmotic power does produce substantial amount of energy, as long as the membranes are clean or their pores unblocked.
Experimentally you would have salt flowing through the electrodes, and chlorine ions flowing through the membranes. In fact, you have voltage across the electrodes, and voltage across the membranes. Both these processes could generate a huge amount of electricity, by summing the potentials. There are other elements in seawater like magnesium, calcium, nitrogen, phosphorous and sulfate. It remains to be seen how these naturally occurring elements add up to the process. Estuary energy can be produced throughout the year, unlike wind or solar.
By tapping into other saltwater gradients present in lakes, waste water facilities and geothermal resources, researchers are hopeful that this would lead to another form of green energy like solar or wind.