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About LinkBacksYeah that's one way of looking at it. Sharing the fuel/environmental cost of shifting that 1+ ton metal box between more people makes a lot of sense from an efficiency standpoint!
Yeah that's one way of looking at it. Sharing the fuel/environmental cost of shifting that 1+ ton metal box between more people makes a lot of sense from an efficiency standpoint!
Maybe not.Originally Posted by watercooled
I have absolutely no definitive idea, but from a very quick read of the various different grades of diesel and AvGas, I would *think* the latter spits out more pollution. So aircraft wins on engine efficiency, but then starts to lose that lead when you see how environmentally inefficient it is.
I guess it's how much pollution results from how much fuel used per kilo of weight per mile... or something clever like that.
Average out passenger weight, so you can compare that to cargo weights. Include passenger luggage, human support like food and water, and any other consumables like bed linen and little bottles of shower gel.
Yep... always a use for numbers.
Costs and fuel used, divided by number of passengers, equals base rate for the fare you charge.
Costs to include driver wages, vehicle maintenance, licencing and all the other gubbins, too. Don't forget to also add a profit margin and then VAT to that base rate!
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Jet aircraft use Jet fuel. Basically Kerosene. In the same environment, it burns very slightly cleaner than #2 Diesel, but not enough to make much difference. Avgas is used by piston aircraft which aren't very common in passenger service. They are more fuel efficient than jet engines, but have many disadvantages. Avgas is a high octane petrol which is still a leaded fuel. Not great for the environment, but very little is made and there isn't a suitable alternative.
We need numbers, though, Tee... Can't have an internet discussion without numbers. Preferably links to some university studies, too!
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Don't large ships use something heavier than what we'd call diesel too? I'm not sure on that one but I suspect some, especially older ships, would use HFO?
Edit: Found something to back that up: https://www.independent.co.uk/enviro...-a8502771.html
[People are generally a poor measure of anything. Tons is a standard that can be used to measure anything with mass, including people. Were the objective merely to move people, you could pack them on a ship as densely as an airliner and the PMPG of the boat can exceed that of any aircraft. What you can not do is build a boat that travels as fast as an aircraft or an aircraft that travels as slowly as a boat. That fact biases PMPG comparison towards the aircraft.
A jet aircraft is not a ship. Comparing PMPG across transport sectors is not logical. The comparison breaks the rule of identity and the conclusion breaks the law of non-contradiction. This is the logical statement you need to refute to avoid a circular argument. Otherwise, you invite me to keep on proving how a jet airliner is not a ship.
Go ask the people standing in the arrivals hall at the airport, before they board a taxi, coach, train, car, transfer to another flight. Everyone who travels IS bound by the speed they travel, is not an implication, it is self evident.I think you might be the one redefining reality TBH. Why would a passenger going on holiday or a standard business trip not stop when they get to their destination? You're implying the amount of people travelling so frequently they're basically bound by travel speed make up something of a majority, or possibly all passengers depending how you interpret your post?
A 747-400 burns around 1 gallon of fuel a second and carries around 524 passengers (being kind). That is 3600/534 = 6.87 Gallons per passenger per hour. The Oasis of the Seas (a large cruise liner) burns around 3.16 gallons per second and carries 5400 passengers (being unkind). That is 11376 / 5400 = 2.10 Gallons per passenger per hour.
Unlike the aircraft, the cruise liners PMPG encompasses pretty much the entire fuel consumption of the passengers for the duration of the trip. To make a fair comparison of fuel efficiency using PMPG we would need to wait for the cruise liner to cover the same distance and track airline passenger average fuel consumption for the duration. But the plane does not stop, the air passengers do not stop. The cruise liner can never catch up and the air passengers onward fuel consumption is not tracked. Cross comparison of PMPG strips away a great deal of pertinent data from one side of the comparison. The comparison is biased towards the aircraft due to the aircraft being so much faster than the ship.
The one way you should interpret my post is, cross comparison of complex averages is a nonsense. Any other interpretation is your own inference. You might credibly argue that cross comparison of PMPG reveals a facet of human behaviour, and that I accept.
That is not a sound comparison. Jet airliners must travel at a certain velocity and consume a certain volume of fuel to take off and stay airborne. A ship is almost the opposite. A ship burning no fuel remains afloat (virtually) indefinitely. A ship can harness the tide to overcome inertia and contribute to momentum. Ships have to be tied down to stop them drifting off inadvertantly. The volume of fuel a ship burns for a given passage is somewhat more the choice of direction and velocity.For passenger ships, a more substantial portion of energy goes into moving the vehicle itself when compared with a plane.
Occam's Razor murders the last clause in the statement. We were so close to an agreement.A more sensible approach would be to not take overseas holidays one after the other, or to use the Internet to do business rather than flying everywhere, where possible, rather than deliberately travelling less efficiently as a way to limit the amount of journeys.
The empirical evidence is clear by the way. The decline of the passenger liner is well documented. The migration to trans-continental jet travel was driven by the desire for speed, not energy efficiency. The same desire drove the migration from sail to steam. As the developed world sped up, people became busier and consumption rates climbed accordingly. Growth in consumption rates continues to outpace and overwhelm energy efficiency savings. The growth in jet airliner travel is contributing significantly. Presuming a proportion of air passenger miles are not strictly necessary, jet airliners create potential to waste vastly more energy than surface modes. Efficiency is not conservation. We might choose to slow down or be forced to slow down.
The error in your attempt at re-statement was obvious but you made it.Cargo may be a different story, but we're talking about passenger travel here.
Which is an obvious statement but a rather pointless argument to make in today's world.
You may be talking about passenger travel, I am talking about human consumption. Human nature is to take more than the next man (or woman). Jet airliners enable greater human consumption. Presuming a proportion of consumption is not necessary, jet airliners enable a great deal of additional waste. The same is true of just about every technology that has allowed the human race to do more, travel further, in less time.
The consumerist economy rewards over-production and over-consumption. That is today's world. A world where talented engineers are paid to design products to be un-repairable and need replacement at an increasing rate. Where bit-mining can consume more electricity than Cyprus, but somehow that makes sense. Where lobby groups persuade holiday makers that sitting on an A380 consuming ~9 Tons of fossil fuel per hour provides them with a more effective life.
Consumption for consumption sake is lunacy. I think it needs to be addressed before tomorrow's world becomes any more dystopian than it looks already. The question I implied at the end of my first post was, how might we do that? I think that is a much more interesting question than arguing over a clearly flawed comparison.
Please do me the courtesy of pointing out where and what logical rule was broken.We don't need a simple analogy, it's quite clear what you're saying, it's just illogical. To honour the analogy, freeze the second meal for the next day, or take turns to pay with a friend.
You have not honoured the analogy. Where did the money for the freezer and the electric it consumes come from? The concept of a friend does not scale up unless we adopt some form of socialism. The capitalist version has you selling meals to your mate to pay for financing the freezer, buying and selling more to keep the freezer full and working at maximum efficiency. Buying and selling more to pay to empty the bins that are overflowing with the additional wrappers. All to save a buck on a meal you do not need.
Yes. That is how modern value pricing works.The analogy suggests taking extra passengers on board the aircraft just for the sake of it; wastefully, in order to balance the efficiency for no particular reason.
Your point on emissions is valid, I would say. The shipping industry needs to be de-carbonised and that has already started. The first battery container ship is due to enter service this year.
Very interested in this battery container ship. Can you provide more information? It's about the least practical vehicle to move on battery power...
It could be practical if it operates in the tropics with a large solar array, or as a hybrid. Although a container ship cruising at a constant speed are fairly fuel efficient anyway.
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I'll have to condense things down a bit to make this more readable.
Silly comparison. Not least because being comfortable for a few hours is vastly different to being comfortable for many days to weeks. And that you'll struggle to fill a ship with enough people going to one destination. And all just to meet the efficiency of a transport method we already have.
It's an objective comparison, you're the one who's biasing it with cherry-picked information, moving the goalposts as such, in an attempt to prove a point. I, and others, were very simply comparing the efficiency of moving passengers between locations. The outcome of that in the real world is quite obvious.
It is when your objective and the outcome is the same.
And that's different to arrivals at a marine terminal how exactly?? Also why would people not have to use onward travel when leaving a ship? Aircraft can generally get people fairly close to their destination, but good luck getting a ship to stop at Birmingham!
There's that argument again. Power is not energy! Time is a critical component when calculating efficiency, which you are again totally ignoring. We see this with computing too - it's not uncommon for modern CPU cores to be more efficient (in terms of energy consumed per task) in a higher-power state due to things like leakage, so by design many will boost, get the work done quickly, then power gate to reduce leakage. Your argument is like saying a given CPU is more efficient because it uses 50W rather than 70W, even though it takes ten times longer to complete the same task and the energy consumed, say in Joules, is far greater.
Again, not when you're comparing like-for-like i.e. energy consumed per passenger when transporting passengers. As you put it: Any other interpretation is your own inference. You might credibly argue that cross comparison of PMPG reveals a facet of human behaviour, and that I accept.
It is a sound part of an explanation (though of course not the whole story, but I never claimed it was) for the vast discrepancy in efficiency between a ship and a plane.
Occam's Razor has nothing to do with it. If anything, you're the one who's making a vast amount of assumptions about human behaviour rather than a simple objective comparison regarding transport efficiency. Travelling in a less efficient way in order to limit journeys is exactly what you're suggesting.
Agreed. Apart from the part in bold. It does allow people to consume more energy if all they're doing is travelling back and forth on airliners, but I don't see that as a particularly realistic scenario for the overwhelming majority of passengers. It does make further travel within a given time-frame feasible, but that same argument could be extrapolated to many aspects of modern life, and again way outside of the scope of what we were discussing.
For the record, don't for a minute think I'm saying aviation isn't a concern WRT emissions. That much is obvious. Just, suggesting a less efficient mode of transport is more efficient is something of a hard sell outside of very specific, you could say cherry-picked, scenarios. It's a valid point that planes consume fuel very quickly by comparison, but that's undeniably only half the story. It's like power generation, a CCGT station uses vastly more fuel per unit time than some diesel backup generators, but is also vastly more efficient at generating power. It's quite simply pointless to compare rate of consumption in isolation.
Using rough Googled figures - That plane is flying for less than 8 hours. The ship is under way for 7 days.
Not sure what the 3600 and 11376 are supposed to be, but 3600/534 is 6.74...
Also, not exactly definitive but this cropped up when I was googling the distances: https://science.howstuffworks.com/tr...uestion192.htm
Linked rather than copy-pasta.
Then don't look at touring ships that stop at every port and assume their entire journey is somehow valid. Use a tanker, or a Transatlantic voyage from Port A to Port B with no stops, or something.
Southampton has an airport, right? So does Florida? Both have sea ports too?
Use that trip, and give or take a couple of miles for distance between airport and . Then break it down to weight moved per gallon of fuel used per hour elapsed per mile covered... and then tell me how much pollution was kicked out as a result.
IF the tide is favourable, then potentially yes to some degree.
If it's not, which is often, then it burns even more fuel and takes longer, as it's battling against the tide.
Depends what you consider to be effective.
Diesel engines may be more effective in terms of fuel consumption, but not in terms of pollution.
Actually, the capitalist version is about restructuring the existing Freezer department and merging the Work Lunch team into the existing Dinner team, alleviating the requirement for the supplementary Fridge department at the office, while also entering into a Joint Venture with your work colleague ('friend' is no longer an acceptable term for office personnel, as it may offend those without interpersonal skills) for the purposes of a mutually beneficial cost savings exercise.
There are already makers of high-end luxury motor yachts that use solar panels to charge up their batteries. They don't (to my knowledge) power the propellers though, even on small and light vessels like these 75-footers. They're just to charge the electrics.
However:
https://www.kongsberg.com/maritime/s.../?OpenDocument
https://spectrum.ieee.org/transporta...on-the-horizon
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As suspected, probably worse for the environment in terms of tonnage per mile, than diesel bulk cargo, due to the inefficiency of having to drag around almost half the ships cargo in batteries.
Solar/battery is one thing, but there's a better renewable resource - wind! Just imagine if boats made use of that!
Zak33 (29-07-2019)
Depends. Some trawler yachts weigh a lot more than some luxury motor yachts, but use far less fuel because they're only chugging along at 4kts as opposed to 9kts. Seriously, that small bump can see your efficiency go from 6.7nmpg down to 1.5nmpg. Go higher and both your efficiency and range drop to less than a tenth.
But again, you'd need to work out how much fuel it uses to move one unit of weight over one mile (A), and how much pollution (B) that particular fuel produced per unit of A. In the case of the MV Yara Birkeland here, it'd be down to how much pollution is produced in the course of generating the electricity. If it's off a nuke plant, presumably that's a much lower B value than if it's off a coal plant, for example.
You'd probably create too much drag from having a massive windmill atop your radar mast... and it'd shed the sails, if you tried that one!!
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Zak33 (29-07-2019)
This particular ship is only operating in Norway, so probably mostly Hydro power..
Yeah there's massively diminishing returns when you want to move a ship more quickly.
For way of comparison, the now-retired Type 42 destroyers had two sets of engines, 5340shp Tyne turbines, and 50,000shp Olympus engines. Unless there was a call to travel at top speed, the ships would often run with just the Tyne engines for sake of efficiency.
I know there are other losses to consider, but travelling at 18kn was possible with just the Tyne engines, and both Olympus engines allowed travelling at 30kn.
Weight is a terrible measure of the capability of a vehicle, since passenger travel and the vast majority of freight is limited by bulk rather than weight. The limit on almost any passenger aircraft is based on the number of seats which can be fitted, with the width and legroom requirements. Typically this is tens of thousands of pounds less than the payload the aircraft can carry. Similarly, with an ocean liner, the limiting factor isn't the weight of the passengers, but the space taken for staterooms, along with dining areas, etc, that are required for a lengthy voyage.
The same is, mostly, true for freight. Freight aircraft are typically loaded close to their physical capacity, and rarely close to their maximum weight limit, although this does happen on occasion. Partly this is due to the types of freight moved by air. I've flown a plane filled with nothing but fresh cut flowers, for example. Consider your last Amazon Prime delivery. They probably used a Cubic foot of box to send you an SD Card.
Container ships are usually packed with containers on deck to the point of stability. It's bulk that keeps piling up until they get too top-heavy for more. The benefit here is that freight can be packed a lot more densely than people can for a longer period.
PMPG works for comparing moving people, and it's a lot better for the environment for you to fly from the UK to the US than it is for you to take a boat, and to a degree this is reflective in how much cheaper it is, as fuel is a major cost. If you wanted to ship your car over, it's a lot better to put it on a ship than to fly it. Again, the relative costs, to some extent, reflect the fuel used.
watercooled (27-07-2019),Xlucine (27-07-2019)
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