• kakes@sh.itjust.works
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      6 months ago

      If we’re naming modes of transportation that pollute, it would be remiss not to point out the worst one: ships.

      • grue@lemmy.world
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        6 months ago

        On the contrary: ships are the third-best one when you consider greenhouse gas emissions per ton-kilometer of cargo moved, which is the metric that matters. They only pollute a lot as a category because there is so much fucking shipping going on. (Reducing that is also an issue, but one for a different thread.)

        The only things better are bicycles and sailboats (because they use no fossil fuels at all). Even trains are less efficient, although in the long run they have the advantage of being possible to electrify and run on renewables.

        Granted, the other pollution (not greenhouse gas) from ships is terrible because they use the cheapest, nastiest fuel. But as bad as that is, it’s still a much, much lower-priority concern than climate change.

        (TBH, what we really need are nuclear cargo ships.)

          • grue@lemmy.world
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            6 months ago

            The biggest problem with your traditional square-rigged ships is that the masts get in the way of modern cargo-handling methods.

            Also, according to Wikipedia, the largest sailing ship ever made (SS Great Eastern) had a gross register tonnage of 18,915, while the largest container ship (MSC Irina) has a gross tonnage1 of 233,328. In other words, the sails would have to be an order of magnitude larger than any that have ever been made before.

            There are some newer sail technologies, such as rotor sails and kite sails, but those are apparently designed to shave 5-10% off the fuel consumption of a primarily engine-powered ship, not act as the primary means of propulsion.

            And the other big problem with any of those technologies is that even if they could propel the ship by themselves, they still can’t fully replace engines because logistics companies won’t tolerate getting becalmed anymore. And even if that weren’t an issue, you’ve still got to have an engine for maneuvering in tight channels and ports anyway.

            In order to completely eliminate having to burn fuel, nuclear really is the only option.

            (1 GRT and GT aren’t quite the same thing, but there’s no simple conversion between the two. That said, they should “not differ too greatly” according to Wikipedia.)

            • HappycamperNZ@lemmy.world
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              6 months ago

              Oh, I fully agree there are multiple logistics and engineering challenges that would need to be overcome. But im also aware we are orders of magnitude more advanced than when Great Eastern was designed and built - we used to think we would never get to the moon because a spacecraft couldn’t carry enough coal.

              If you could eliminate 80% of fuel costs you could make smaller vessels much more cost effective which, let’s be honest, is the biggest hurdle. Make it sail 95% of the time, small maneuvering engine and electric tugs can eliminate alot of the variable costs… and they only cruise at 10-12kt anyway.

              • grue@lemmy.world
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                6 months ago

                If you could eliminate 80% of fuel costs you could make smaller vessels much more cost effective

                Ships don’t work that way. There are a couple of reasons other than fuel economy why they keep building them as big as they can:

                • Hull speed is proportional to waterline length. In other words, bigger ships can go faster.

                • Bigger ships have better economies of scale for the crew.

                Also, winds aren’t reliable enough for any ship to sail 95% of the time, unless you count being becalmed as “sailing.”

                • HappycamperNZ@lemmy.world
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                  6 months ago

                  Yes, theoretical hull speed is proportional to hull speed, but mondern cargo ships aren’t optimized for speed - old school clippers were.

                  They are also more cost effective for crew - which is why you need to automate as much as possible. Electronic winches, hydraulic booms or sheets, instance access to weather, Electronic monitoring, tides and conditions forecasting and access for a harbour pilot to take over could eliminate alot, if not all of transit crew.

                  Will it be as fast and reliable- no. But if you can make the cost savings outweigh the drawbacks you can make a presentable business case.

    • pot_belly_mole@slrpnk.net
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      6 months ago

      I don’t understand your logic. Say SUV’s were on average 50 % worse emitters than regular cars. Now when picking a car you face the choice of emitting 1 unit or 1.5 units of emissions, for basically the same service. If we look around, these kinds of choices are everywhere. Transportation, food, housing, electric power. Often the difference is even bigger than 50 %. Being consistent in choosing/forcing/promoting the better alternative results in a HUGE difference. Of course, if you look at one decision, it’s not decisive. But transportation and cars definitely are a major factor.