Maersk installed 100-foot-tall rotating sails on one of its tankers

Post by cwmoore » Fri, Aug 31, 2018, 3:48 PM UTC

jacquesm wrote: post #56

cwmoore wrote: post #49

Earlier quoted context omitted.

Yes, salt water is corrosive. And yet, there are metal ships with viable lifetimes. This sub-thread is a bit less helpful than I am asking for. Edit: Come on. It's not impossible to engineer for ocean use. Wave power generation: https://www.bbc.co.uk/news/uk-scotland-scotland-business-250... Longer term: https://en.wikipedia.org/wiki/Submarine_power_cable

Salt water is so corrosive that there is a whole branch of materials science dedicated to coatings and all kinds of other anti-corrosion measures such as galvanic protection using sacrificial material. The evidence is overwhelmingly on the side of statements such as 'simple systems that work well on the shore need extensive rework for ocean deployment assuming they can work at all'. Even a simple scratch is enough to…

Post by blueprint » Fri, Aug 31, 2018, 3:51 PM UTC

cwmoore wrote: post #60

telchar wrote: post #58

Earlier quoted context omitted.

Here's a source for you that mentions that even some typical formulations of stainless steel are susceptible to corrosion in saltwater: https://www.clintonaluminum.com/304-stainless-steel-in-seawa...

White bread is bad in saltwater too, that doesn't mean there aren't better materials for the application. https://www.quora.com/Does-aluminium-react-with-salt-water https://en.wikipedia.org/wiki/Organic_solar_cell

Post by GlenTheMachine » Fri, Aug 31, 2018, 3:54 PM UTC

cwmoore wrote: post #30

village-idiot wrote: post #21

Earlier quoted context omitted.

I think the issue would be salt water. Salt water destroys everything , I can’t imagine that a PV array floating in water would have a good life expectancy. On the plus side, if the insulation fails you could turn container ships into accidental fishing boats.

> Salt water destroys everything This is the statement I hear relating to all kinds of ocean-based renewable energy ideas. Sources are never provided. The problem must have to do with economic viability and the replacement/maintenance costs exceeding savings. Could you supply sources to elaborate on where the break even point of solar tail (or any two other ocean renewable energy) systems would be as relates to costs…

Post by IronWolve » Fri, Aug 31, 2018, 3:54 PM UTC

taneq wrote: post #48

robfitz wrote: post #9

Earlier quoted context omitted.

They claim 7-10% reduction in fuel usage, with fuel making up 60% of their total costs. Given that they soon expect to be spending $5 billion/year on fuel for 800 ships, fuel spend is a bit north of $6 million/year for an "average" ship. But size seems to vary widely (they note that only the 80 of their largest ships are being considered for these sails). At an installation cost of $2 million, saving 10% of an "avera…

I think that's something we lose sight of in software sometimes, where we're used to some token effort improving performance by 10x or more. In the real world, if you can make something 10% more efficient, that's a game changing, industry conquering advantage.

Post by ant6n » Fri, Aug 31, 2018, 3:58 PM UTC

tomtimtall wrote: post #40

ValleyOfTheMtns wrote: post #23

I've been wondering why shipping companies haven't been doing this for years now. Whenever I brought it up with friends they would say it's probably not worth the effort, but I can't see how it wouldn't be worth it. It's essentially free energy to help move the ship around. Got to say, I feel vindicated by this story.

Essentially free energy... except the cost to install, the cost to operate, maintainable and of cause the cost when one of them breaks and causes damage. For a lot of these “why don’t they just” the answer is simply that they did the math and saw too small an upside for too big a risk. They are trying this out to see if the overall concept works in practice or if it falls short.