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Re: [carfree_cities] Re: Fuel-Sipping Trains

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  • J.H. Crawford
    ... That s physics at work: resistance increases with the square of the speed. There are ways around it, to a degree. If the trains are light, energy
    Message 1 of 18 , Jun 13, 2007
      Joel Siegel said:

      >High-speed rail does not escape criticism, however.
      >
      >"The obvious replacements for planes are scarcely better. Fast passenger ships appear to be even worse for the environment than jets. ... [Paragraph] Nor are ultra-high-speed trains the answer. Though trains traveling at normal speeds have much lower carbon emissions than airplanes, Professor Roger Kemp of Lancaster University shows that energy consumption rises dramatically at speeds above 125 miles per hour. Increasing the speed from 140 to 220 mph almost doubles the amount of fuel burned. If the trains are powered by electricity, and if that electricity is produced by plants burning fossil fuels, they cause more CO2 emissions than planes. Running trains on renewable electricity is certainly possible, but this faces problems: Trains must run on time, and that means there is little room for 'demand management,' which means reducing the electricity load in response to fluctuations in supply. In all transport systems, high performance is incompatible with low consumption. The faster you go, the more energy you need."

      That's physics at work: resistance increases with the
      square of the speed. There are ways around it, to a degree.
      If the trains are light, energy requirements are much
      reduced. If the streamlining is good, resistances is
      also reduced. I have heard (no substantiation) that the
      double-decker TGVs running from Lyon to Paris use about
      the same amount of seat-mile energy as conventional
      trains despite running at 300 km/hr or so. They are
      very light weight, have low frontal area for the number
      of seats, and the streamlining is good. That's about
      the limit of the technology, IMHO. I also think that
      it probably doesn't make sense to run trains much above
      300 km/hr. The newest TGVs are 360, but the cost is
      large and the actual reduction in travel time is not
      great. Not worth the cost?

      It is NOT all that hard to store electricity, although
      there are losses. Pump storage is proven and can be
      used, essentially, to store electricity. Pump water
      up hill when there's plenty of electricity. Let it
      flow back down hill to turn generators when there's
      not enough. Losses are about 30% IIRC.

      But, in general, things are probably going to have to
      slow down, unless you go with the nuke option.

      Regards,

      Joel




      ----- ### -----
      J.H. Crawford Carfree Cities
      mailbox@... http://www.carfree.com
    • dawie_coetzee
      There are secondary effects that are not reflected in any of these comparisons. For instance, a railway station within easy reach of pedestrians will both be
      Message 2 of 18 , Jun 14, 2007
        There are secondary effects that are not reflected in any of these
        comparisons. For instance, a railway station within easy reach of
        pedestrians will both be symptomatic of and increase the viability of
        pedestrian-accessible destinations in general. Compared with car travel
        there is therefore at worst a lesser tendency to generate a need to
        travel. In practice there might well be a tendency to reduce the need
        to travel.

        We all know how car-dominated environments create dependence on cars,
        requiring that we take longer trips more often. A truer comparison
        might be 1km by train to perhaps 8km by car, 7km of the latter
        contributed solely by the sort of environment associated with that mode
        of transport. Has anyone actually quantified this?

        -Dawie

        --- In carfree_cities@yahoogroups.com, Richard Risemberg <rickrise@...>
        wrote:
        >
        > > Fuel-sipping trains
        > > June 11, 2007
        > >
        > >
        ...
      • Jym Dyer
        ... =v= In the U.S. cars are rarely filled to seating capacity. The average ridership is slightly over 1 person per car. So it s hard to take numbers like that
        Message 3 of 18 , Jun 14, 2007
          > A 26 MPG Honda Civic fully loaded with five passengers?
          > 130 passenger miles per gallon.

          =v= In the U.S. cars are rarely filled to seating capacity.
          The average ridership is slightly over 1 person per car.
          So it's hard to take numbers like that seriously.

          =v= Also, wow, Honda Civics are way down to 26 MPG now?

          =v= One complication in these comparisons is that passenger
          rail in the U.S. has very little dedicated track. For the
          most part Amtrak runs on track owned by freight companies.

          =v= Another complication is that Amtrak is subject to a dogmatic
          "business model" that competing modes are not. The ideology is
          that Amtrak should turn a profit, and there's a budget fight for
          its small subsidy every year. So service keeps getting hurt and
          the trains do such things as haul freight along with passengers
          (preventing a switchover to lighter trains).

          =v= Meanwhile, of course, cars and planes enjoy a staggeringly
          high and rarely-mentioned subsidy.
          <_Jym_>
        • Greg Steele
          There is an accountant joke I once heard where three accountants are applying for an executive position. The CEO of the company asks each of the candidates
          Message 4 of 18 , Jun 14, 2007
            There is an accountant joke I once heard where three accountants are
            applying for an executive position. The CEO of the company asks
            each of the candidates what is 2+2. Two of the applicants says 4
            and don't get the job. The third, who gets the job, asks the
            CEO, "What do you want it to be?"

            I am not aware of any studies that would answer some important
            questions raised in this discussion and in the larger discussion
            about funding for rail.

            The laws of physics say that the faster an object moves through
            space the more resistance it will encounter, therefore, more energy
            is required to achieve higher speeds. I am sure that the field of
            aero-dynamics has can provide formulas to quantify this in terms of
            frontal area and speed. What is lacking is a quantified functional
            relationship of increased weight and drag from adding one additional
            coach car to a train-set. Intuitively, it seems that adding cars
            (therefore, more passengers) would add a very small increase in
            energy usage while greatly improving the passenger- miles/gallon
            ratio. Therefore, one could state the passenger- miles/gallon to be
            anything they wanted to by adding or subtracting the number of
            coaches/passengers per train. There are of course practical limits
            to how long a passenger train can be in terms of station platforms
            and crews. In addition, at some point the weight of the train will
            require an additional locomotive which alters the equation.

            I have heard passenger – miles/gallon figures that are all over the
            map. Until someone does some hard science on this that deduces the
            issue to friction of steel wheels on steel rails vs. rubber wheels
            on assault. I suggest that we look at any calculation of passenger –
            miles/gallon will a great deal of skepticism.
          • J.H. Crawford
            This is all pretty tangential. The basic physics are: It takes lots of energy to accelerate a train, and the total amount of that energy increases with the
            Message 5 of 18 , Jun 14, 2007
              This is all pretty tangential. The basic physics are:

              It takes lots of energy to accelerate a train, and the
              total amount of that energy increases with the SQUARE
              of the speed.

              It takes lots of energy to drag trains up hills; this
              is related to weight and elevation, not to speed.

              Long, thin objects have high "Reynolds Numbers" which
              means that the amount of air drag is considerably lower
              than for short, fat objects.

              Mass of a train has no effect whatever on the amount
              of aerodynamic drag.

              Light, long, streamlined trains are the most efficient.
              Slower trains are more efficient than faster ones, all
              other things being equal.

              Again, the TGV double-decker gets good efficiency despite
              its very high speed.

              Regards,


              ----- ### -----
              J.H. Crawford Carfree Cities
              mailbox@... http://www.carfree.com
            • Matt Hohmeister
              Actually, this brings up a question I ve been wondering for some time. In an era of dwindling oil supplies, are we better off with jets or ships? 747 or QM2?
              Message 6 of 18 , Jun 17, 2007
                Actually, this brings up a question I've been wondering for some time. In an era of dwindling
                oil supplies, are we better off with jets or ships? 747 or QM2? Or is there another solution?
                Anybody?

                > "The obvious replacements for planes are scarcely better. Fast passenger ships appear to
                be even worse for the environment than jets. ... [Paragraph] Nor are ultra-high-speed trains
                the answer. Though trains traveling at normal speeds have much lower carbon emissions
                than airplanes, Professor Roger Kemp of Lancaster University shows that energy consumption
                rises dramatically at speeds above 125 miles per hour. Increasing the speed from 140 to 220
                mph almost doubles the amount of fuel burned. If the trains are powered by electricity, and if
                that electricity is produced by plants burning fossil fuels, they cause more CO2 emissions
                than planes. Running trains on renewable electricity is certainly possible, but this faces
                problems: Trains must run on time, and that means there is little room for 'demand
                management,' which means reducing the electricity load in response to fluctuations in
                supply. In all transport systems, high performance is incompatible with low consumption.
                The faster you go, the more energy you need."
              • Richard Risemberg
                ... Ships do not have to be powered by oil or coal. Highly refined sailing vessels with solar auxiliary power for days of calms and for harbor maneuvering can
                Message 7 of 18 , Jun 17, 2007
                  On Jun 17, 2007, at 8:40 PM, Matt Hohmeister wrote:

                  > Actually, this brings up a question I've been wondering for some
                  > time. In an era of dwindling
                  > oil supplies, are we better off with jets or ships? 747 or QM2? Or
                  > is there another solution?
                  > Anybody?
                  >
                  Ships do not have to be powered by oil or coal. Highly refined
                  sailing vessels with solar auxiliary power for days of calms and for
                  harbor maneuvering can move considerable tonnage and numbers of
                  passengers. However, it is obvious that if we are serious about
                  sustainability, we will have to accept that international trade and
                  travel will be slower and more expensive. (Although someone, upon my
                  telling them this, suggested that sail transport labor costs could be
                  lowered by using crews of slaves...I hope they were kidding.)

                  And no, I don't think nuclear-powered ships are the answer!

                  http://tinyurl.com/25u5bt

                  Rick
                  --
                  Richard Risemberg
                  http://www.bicyclefixation.com
                  http://www.newcolonist.com
                  http://www.rickrise.com
                • dawie_coetzee
                  Localization. ...it is obvious that if we are serious about sustainability, we will have to accept that international trade and travel will be slower and more
                  Message 8 of 18 , Jun 18, 2007
                    Localization.

                    "...it is obvious that if we are serious about sustainability, we
                    will have to accept that international trade and travel will be
                    slower and more expensive."

                    Precisely. I know Joel Crawford takes a somewhat contrary position in
                    his book, but I'm a firm localist. Pedestrian cities and localized
                    economies are perfect for each other. Indeed, the one only comes to
                    full fruition in the context of the other.

                    -Dawie



                    --- In carfree_cities@yahoogroups.com, Richard Risemberg
                    <rickrise@...> wrote:
                    >
                    > On Jun 17, 2007, at 8:40 PM, Matt Hohmeister wrote:
                    >
                    > > Actually, this brings up a question I've been wondering for some
                    > > time. In an era of dwindling
                    > > oil supplies, are we better off with jets or ships? 747 or QM2?
                    Or
                    > > is there another solution?
                    > > Anybody?
                    > >
                    > Ships do not have to be powered by oil or coal. Highly refined
                    > sailing vessels with solar auxiliary power for days of calms and
                    for
                    > harbor maneuvering can move considerable tonnage and numbers of
                    > passengers. However, it is obvious that if we are serious about
                    > sustainability, we will have to accept that international trade
                    and
                    > travel will be slower and more expensive. (Although someone, upon
                    my
                    > telling them this, suggested that sail transport labor costs could
                    be
                    > lowered by using crews of slaves...I hope they were kidding.)
                    >
                    > And no, I don't think nuclear-powered ships are the answer!
                    >
                    > http://tinyurl.com/25u5bt
                    >
                    > Rick
                    > --
                    > Richard Risemberg
                    > http://www.bicyclefixation.com
                    > http://www.newcolonist.com
                    > http://www.rickrise.com
                    >
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