Salt solution: Cheap power from the river's mouth - environment - 25 February 2009 - New Scientist The article is about two competing groups developing methods of generating electricity from fresh water, a semi-premeable membrane, and salt water. The first uses simple osmosis to transport water from the fresh to the salt side. The resulting build up of pressure in the salt side will turn turbines. The second just transports ions across the membrane to generate a charge. Both could be potentially be put to use at river mouths with little to no environmental impact.
A lot of technology exists that is only waiting for hardware development to catch up to it. For example, thermoelectric power does have some application, using the Seebeck Effect, which has been understood since the 1820's Thermocouples and thermopiles were at one time used to run room thermostats in homes with coal heat. No electricity required. The gas fireplace in my home uses a thermocouple/thermopile to run the thermostat, no transformer is needed I'm hopeful a suitable membrane can be developed that is also highly resistant to biofilm fouling. Biofilm eventually clogs a membrane, unless you are willing to play with certain mixed oxidants to keep the growth in check
One good aspect is that the engineering approach was sensible. Large enough to encounter (and hopefully solve) the first round of problems. Small enough to overhaul the approach if needed.
