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

[David Lawyer]

On Wed, May 21, 2008 at 07:38:26AM -0700, Dan Kegel wrote:
> On Mon, May 19, 2008 at 9:47 PM, David Lawyer <dave at lafn.org> wrote:
> > The commuter trains waste a lot of
> > energy stopping and starting.  And trains are quite heavy.
> 
> Sounds like a perfect application for regenerative braking,
> at least for electric trains.
> http://www.railwaygazette.com/features_view/article/2007/07/7577/regenerative_braking_boosts_green_credentials.html
> which says it's now common in England, and claims 15% energy savings.

But if you compared regenerative braking with a system which used
coasting, the regenerative savings would not be as great.  I wrote an
article on rail electrification but don't think I discussed coasting.
http://www.lafn.org/~dave/trans/rail/electric_rr.html
Electric Railroads by DL

> 
> > See my:
> > Rail vs Auto Energy Efficiency by DL
> > http://www.lafn.org/~dave/trans/energy/rail_vs_autoEE.html
> 
> You do mention regenerative braking, but don't give any figure
> for the savings from regenerative braking alone, only together
> with coasting (which I gather is your favorite prescription).

Any rational system is doing some coasting so the comparison needs to
be made between an electrified system and a coasting system.  I was
never able to find out how much coasting is done (or has been done) in
the US.  One inquiry said that management encouraged coasting but left
it up to the locomotive driver.  One railroad VP insisted that
coasting wasn't feasible and I told him he was wrong.

> - Dan
> 
			David Lawyer