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For more details, the corrosion process in work here is galvanic corrosion. All metals can be put on a scale of corrosion-readiness, with gold on top. When two metallic parts are electrically connected (as when both of them are inmersed in water), one of them will concentrate all the corrosion, while the other will remain protected.
The corrosion process itself consists in electrons flowing from the corroded part to the protected part, leaving ionized atoms getting away from the metal.
In marine applications, Zinc is used as easy-to-corrode metal, because it protects all metals usually employed in metallic contructions (steel alloys included).
In the image below, Copper is more corrosion-resistant than steel, so steel is corroded. But Steel is mechanically more resistant than copper, so the structure may weaken. The solution is to use sacrificail Zinc connection between both metals. It will protect both pipes, but will require periodic maintenance (easy: to replace the sacrificial Zinc part).
So my question for you is: why do zinc coated things last a lot longer than steel? If zinc is more reactive why doesn't it all just disappear quickly and revert to iron?
I guess zincalum is better because aluminium oxide is so hard and inert.
Thanks for the chemistry lesson!
The german article
mentions a way to use cheap material if an electrical current is forced between the steel and the sacrified material. Zinc is more expensive than steel and electricity should not be a problem, so this variant may be used in offshore windpower. But I don't know for shure.
The picture with the tripod looks like the turbine at Hooksiel (a single near-shore installation for testing and exercising). In 2008 I was on vacation there and saw some preparations for the erection going on.
One of the most common installations for my photovoltaic systems, back when I was a PV designer in the 1990s, was cathodic protection of oil pipelines. (others included powering hazard warning lights on oil rigs, and microwave telecom relays for PDO Oman). Renewables helping out the fossil fuel industry. Strange world, huh?
I would use the old offshore oil and gas platforms to set up high voltage dc converters and the pipelines as protection pipes (or as the ground wire too) for the cables to the shore. Surrounding the platforms big offshore wind farms could be built then.
I'm pretty shure there are studies about that in the drawers of the fossil industry already.
That's the key: they hate losing market share. However, the presently most widespread renewables -- on-shore wind, rooftop solar --, especially when paired with a feed-in law, are structurally predisposed to bring in many new small owners and thus break monopolies. The energy giants will (do) like off-shore wind much more (not to mention centralised solar power, hence the support for the IMO pie-in-the-sky Desertec). But, even when existing energy giants build renewables, they will be less enthusiastic about an accelerated replacement of their existing plants, though.
One whose delusions are out of fashion.
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