20 votes

Why battery powered cargo ships are compelling

6 comments

  1. PuddleOfKittens
    Link
    This article goes through the economics, and why iron-air batteries in particular would be the best choice.

    A problem for ships with marine diesel engines is that engine efficiency drops precipitously at lower RPMs, resulting in diminishing returns for slow steaming. Electric motors don't share this issue, so they get the full benefits of slower travel. An electric ship will use ~1/8th of the power and ~1/4th of the energy to complete a trip if it halves its speed.

    This article goes through the economics, and why iron-air batteries in particular would be the best choice.

    21 votes
  2. [5]
    infpossibilityspace
    Link
    Surprised there wasn't a substantial discussion of diesel-electric powertrains. These use a diesel generator to charge a battery, which in turn powers an electric motor to do the actual...

    Surprised there wasn't a substantial discussion of diesel-electric powertrains. These use a diesel generator to charge a battery, which in turn powers an electric motor to do the actual propulsion.

    Since the diesel generator only needs to keep the battery charged, and battery doesn't need a huge capacity to make the journey itself, they can both be much smaller. This could be a worthwhile middle-ground to pursue (and ships that use this already exist https://en.m.wikipedia.org/wiki/Diesel%E2%80%93electric_powertrain).

    16 votes
    1. [3]
      SunSpotter
      Link Parent
      I’m by no means an expert in the field, or even particularly knowledgeable in terms of marine pollution control. But I do work in the environmental industry, and something I’ve noticed recently is...

      Surprised there wasn't a substantial discussion of diesel-electric powertrains.

      I’m by no means an expert in the field, or even particularly knowledgeable in terms of marine pollution control. But I do work in the environmental industry, and something I’ve noticed recently is that there’s an increasing amount of talk about just ripping the bandaid off and moving towards zero emissions technologies now. Or, in some cases where that’s not possible, coming up with designs that can be retrofitted at a later date to attain zero emission status.

      The idea is that rather than committing millions of dollars in R&D on something that emits less, just for it to be obsolete when stricter emissions standards roll around at some future date, they’d rather just get it over with now.

      10 votes
      1. [2]
        infpossibilityspace
        Link Parent
        Ooh, there's something you can help me with - When it comes to transitioning to zero emission transport, there's an environmental cost to switching to throwing away the old thing and replacing it...

        Ooh, there's something you can help me with - When it comes to transitioning to zero emission transport, there's an environmental cost to switching to throwing away the old thing and replacing it with a new one.

        It seems to me that unless the old thing is absolutely terrible, keeping it running should cause less pollution.

        So rather than incentivising new purchases (most notably in the car industry), should we be encouraging companies to keep their old stuff and mandate that when a replacement is necessary, it must conform to greener standards - rather than subsidising purchases of EVs and scrapping perfectly good machines?

        The UK is trying to do this, mandating that by 2030, 80% of new vehicles must be zero emission, rising to 100% by 2035, and implementing financial penalties to companies that fail (small companies exempt).

        Just wanted to get your opinion on this, cheers!

        6 votes
        1. SunSpotter
          Link Parent
          Hey sorry for taking a while to get back to you. I’m going to sidestep part of your question for a moment to say that this is exactly how US states handle the enforcement of new clean air...
          • Exemplary

          Hey sorry for taking a while to get back to you.

          mandate that when a replacement is necessary, it must conform to greener standards

          I’m going to sidestep part of your question for a moment to say that this is exactly how US states handle the enforcement of new clean air technologies. Rather than forcing companies to get rid of old equipment, whenever they need to replace old equipment, buy new equipment or whenever significant retrofitting would be required for old equipment, we force them to buy the cleanest reasonably affordable technology. This is known as RACT/BACT, meaning Reasonably/Best Achievable Control Technology.

          Well, mostly. It can get complicated, especially when it comes to power plants and other major pollution sources which fall under EPA (Federal, AKA National) review. But that’s the gist of it.

          should we be encouraging companies to keep their old stuff

          I really don’t think so. There are boilers operating in Los Angeles which were built in the 1950s and are still permitted and operating within the law today. They get away with this by doing lots of tiny incremental repairs, and being lucky. So long as the unit never breaks down entirely or requires major repairs, it’s completely fine. But those ancient boilers are bad news. I won’t get into the science of it, but they’re pretty dirty and not doing the local area any favors.

          My point being, companies don’t need encouragement to hold onto old technology. They already have a financial incentive (not spending money) to do so. And holding onto outdated technology for 70 years does the environment far more damage than replacing said technology.

          It seems to me that unless the old thing is absolutely terrible, keeping it running should cause less pollution.

          Continuing off of my prior statement, it’s very much a case by case situation, and you have to assess the annual emissions of the old device, the projected lifespan of the old device, the environmental impact of a replacement, and the lifespan of the replacement. From what I’ve seen though, in most cases when you do that you realize it makes more sense to replace the old device.

          A great example of this is natural gas powered turbines for electric generation, which can easily be modified to accept hydrogen as their primary fuel. So switching over a power plant from gas to hydrogen turbines doesn’t actually produce much waste, and produces immediate environmental benefits. EVs are a more complicated topic of course, but studies have shown that if you keep the EV for at least 10 years before replacing it, then there’s a net benefit to getting rid of your ICE vehicle.

          rather than subsidizing purchases of EVs

          As an EV owner myself, I can tell you that most people who aren’t nerds for EV technology, or passionate about the environment don’t want to be early adopters. Repairs are messy even for professionals, which means longer waiting times for consumers, charging infrastructure is infrequent and unreliable, and the technology itself is unfamiliar, with unfamiliar pros and cons. However early adopters are also necessary for the technology to mature and for companies to be convinced to build more charging stations.

          Hydrogen is a great example of how this can go awry. For various reasons, hydrogen powered cars like the Mirai never took off the way EVs did. They reached their peak several years ago and ever since then sales have been dropping, and now the hydrogen refueling network is collapsing as companies pull out and close down what few stations exist in the first place.

          I think to some extent incentives are necessary if we agree that EVs are better for the environment, at least until adoption of the technology reaches critical mass.

          4 votes
    2. OBLIVIATER
      Link Parent
      It also allows the ships to take advantage of the efficiency of a diesel engine when it's at optimal RPMs. Ships often need to change speed which lowers fuel efficiency, but with a diesel electric...

      It also allows the ships to take advantage of the efficiency of a diesel engine when it's at optimal RPMs. Ships often need to change speed which lowers fuel efficiency, but with a diesel electric setup, those generators can be running at the same level pretty much all of the time.

      6 votes