Well it has been a while since I’ve written anything here; it’s not that I stopped thinking up stuff it’s just that I’ve stopped having time to write it. Right now I am on an airplane so I’ve got nothing but time ;)
Those of you who keep up with kind of stuff are surely cringing, since while the people of N Cal are in favor of clean energy they are not in favor of dams. However, not all hydro power comes from dams. Twice a day San Francisco bay has a 6+ knot (7.5 mph) current as the tide goes in and out, which represents a very reliable source of energy. While it would be nice to build massive tunnels and a more traditional hydro plant the land would cost to much and in order to get maximum advantage the water would have to be flowed from very far back in the bay which would put salt water into traditionally fresh water wetlands, so the environmental impact would prevent it from ever being built. Now there are low speed reversible turbines that could be put in the channels to collect energy, but they might obstruct shipping traffic. There is one place that seems perfect along the bridge pilings. Think about it, you can use the build to run the wire out to the turbines, the pilings increase the velocity of the water so you can get more energy (if you can compensate for the increased turbulence) and ships avoid the pilings at all costs. I am on a plane so I can’t calculate how much energy is available but it is likely enough to warrant at least a pilot project, since most importantly the source of energy wouldn’t be visible so and invisible is the most important requirement.
The Cape Cod Channel would be a great place for the tunnel method since the difference in tidal heights on either side of the channel can be as much as 6 feet. Every day, twice a day water would be forced through the tunnel, to turn a very large but low speed turbine. If nothing else the tidal difference could drive a hydraulic ram, which would pump a much smaller amount of water through a R.O. membrane making fresh water.
Last but not least the Army Corp of Engineers could use a much smaller turbine to both make energy and maintain the Mississippi river. Currently there are areas that have too strong a current and they are trying to slow down to prevent scour, (which moves sediment down stream) by channeling part of the flow through turbines they could reduce the current and by controlling the load on the generator they could control how much they reduced the current. They could also inject air down stream of the turbine to help oxygenate the water which could to reduce the NOx load. (The high turbulence would help the oxygen dissolve in the water.)
I am aware that I haven’t discussed debris screening and a host of other issues, but those issues are too complex for musings at 36,000 feet.
