[SGVLUG] [OT]Hybrids and trains (was fuel prices and the dollar)

[David Lawyer]

On Sat, May 17, 2008 at 11:44:12PM -0700, Mike Rubel wrote:
> > I've seen high claims and they are only true for ideal situations: a
> > train running on level ground with no stops, starts, or slowing down
> > for curves, all seats occupied, moderate speed, etc.  This
> > "hypothetical" train is a few times more energy-efficient than the typical
> > actual train.
> 
> I've found actual numbers, so let's get down to brass tacks.  :)
> 
> >From Amtrak's March 2008 Monthly Performance Report (the most recent
> report online):
> 
> Number of train miles (in thousands): 3189
> Passenger miles (in thousands): 503825
> 
> It follows that Amtrak trains carried, on average, 158 people.  (The load
> factor was 52%, so the average number of seats per train was a little over
> 300.)
> 
> Meanwhile, the average Amtrak train consumed 2.3 gal/mi, or, put another
> way, achieved about 0.43 mi/gal fuel economy, including all stops, starts,
> and idling.
> 
> Thus the actual March 2008 fuel economy, under real conditions and with
> actual passenger loading, was... 68.7 mi/gal per passenger.

This doesn't agree with TEDB (see below) which reports about 50
pass-mi/gal(diesel) or 45 pass-mi/gal(gasoline) for 2005.  Diesel has
about 10% more BTU/gal and to compare to automobiles it's convenient
to covert the reported BTUs to gallons of gasoline.

Could the discrepancy be partly due to the month?  Air conditioning of
trains uses a lot of energy in warmer months.  Also, the high price of
gasoline could be a factor.  I'd like to look into this discrepancy,
but I'm too busy with higher priority tasks and it's not a huge
discrepancy.

> Increasing the load factor, by making Amtrak more appealing (for example,
> by being on time occasionally) would reasonably improve this figure above
> 100 mi/gal per passenger.

I'm not so sure.  In the last years of World War II when trains were
often full, they did get about 100 pass-mi/gal(gasoline) or about 110
pass-mi/gal(diesel).  So we've done it before, but only during a time
of gasoline rationing and when the relative size of the rail network
was larger than today.  See my article on the estimates from 1936 to
1963 for the U.S.:

http://www.lafn.org/~dave/trans/energy/PM-gal_36-63.html
USA Railroad Passenger-Miles per Gallon 1936-1963.

The average for those years (excluding the war years) was a little
over 40 pass-mi/gal.  1936 was 50 pass-mi/gal and is partly due to
introducing the limited supply of diesel-electric locomotives to those
routes with the highest traffic density.

> 
> And this factors in lots of older and less-utilized trains and empty
> seats.  I'm sure the figure for Northeast Corridor trains, or the
> Pacific Surfliner that I take, would be much higher, even though
> they include an extra mostly-empty cars for baggage and half a car
> for snacks and dining.  I'd also bet commuter trains like Metrolink,
> which are relatively light and forgo luxuries like dining/snack and
> baggage cars, are better still.  But Metrolink doesn't provide fuel
> economy data.

Well, Transportation Energy Data Book (TEDB) does (for commuter trains
nationwide) and it's been about 45 pass-mi/gal (gasoline) from 1984
thru 2005.  It's reported like "2,784 BTU/pass-mi" which one converts
to pass-mi/gal by dividing 125,000 BTU/gal(gasoline) by this number.
See http://cta.ornl.gov/data/tedb26/Spreadsheets/Table2_14.xls
TEDB26 EI Non-Highway Excel 97-2000

So commuter trains are no more energy efficient than Amtrak which for
2005 came in at 2,709 BTU/pass-mi.  The commuter trains waste a lot of
energy stopping and starting.  And trains are quite heavy.  See my:
Rail vs Auto Energy Efficiency by DL
http://www.lafn.org/~dave/trans/energy/rail_vs_autoEE.html

			David Lawyer