Railroad Downgrade Power Generator

Since I'm going to be using the terms a lot, let me begin by offering some railroad-to-English translation:

'downgrade' = 'hill with train going down it'

'unit' = 'x number of locomotive(s) coupled together and under power'

'string' = 'x number of cars coupled together'

'train' = 'locomotive(s) coupled to string of cars'

When a train crests a ridge and starts down the other side, the unit has hundreds or even thousands of tons coming down behind it. It manages this weight by braking, of course, using one or both of two systems: 1) -friction brakes, in which cast steel shoes (on the locos and some especially heavy cars, like tankers) or composite rubber shoes (on the majority of car types) are applied directly to the steel wheels via impulse air (the system is complicated to explain and irrelevant to this idea), or 2) - dynamic braking, in which (to put it very simply) the deisel-electric motors that drive each axle on the unit are "reversed," turning them into dynamos that slow the train by building up massive E-M resistance (again, a gross over-simplification), incidentally charging the unit's batteries but bleeding off most of the energy they produce by converting it to heat and blowing it out the top of the locos.

This is wasted energy.

I propose that, on trains scheduled to traverse significant downgrades, a special car be coupled to the end. As the balance of the train shifts over the hill, this car deploys a pair of tailhook-style catch devices (activated by a light impulse on air-brake system, but not enough to set the brakes), latching onto receivers mounted on fairleads on each side of the track. As the train descends, the tailhook car pulls cables attached to generator cars running on parallel tracks. These are simply weighted flatcars fitted with the same dynamic motivators that propell a locomotive; the generator cars are coupled into strings calculated to offset the weight of the descending train, and they roll up the hill as the train rolls down. The dynamic braking is done by the generator cars instead of the unit, but instead of the power thus generated being converted into waste heat, it is sent to transformers via thick cables and converted to AC power, then fed directly into the power grid. At the bottom of the down grade, a simple trip mechanism unhooks the receiver cables and resets the tailhook car.

After the train is uncoupled from the cables and goes clickety-clacking off on its merry way, the generator cars roll back down the hill, using their motivators as freewheeling dynamos until it's time to slow down, when they once again employ dynamic braking-- generating electricity the whole time.

Going by some rough calculations done completely in my head based on information half-learned several years ago, I figure this would work best on 3.5 downgrades (because under that, drivers tend to use just friction brakes, even though they're not a-sposta, don't ask me why) of at least 1 1/4 miles in length. There are over 1,000 such downgrades in the US and Canada on key routes alone, not counting Class C roads and locals.

Setting this up would obviously require some considerable initial investment, which is anathema to the operators of railroads; perhaps the electric companies who stand to reap power from the installations could pony up a little dough, or (dare I say it) even the government. The US is a little tight right now, sure, but I hear the Canadians have wads of cash to blow right now, what with just having sold Vancouver Island to the Borg Collective. As for the physical infrastructure, all of the bits and pieces already exist, and specialty cars are not hard to build (my work partner and I built quite a few unique cars during my time with the railroad). The maintainance costs would be relatively low (by RR standards). I'm not sure how much power it could generate, but I am reasonably confident it would pay for itself in short order. I generally operate under the principle that anything is better than nothing

As an afterthought, I just realized that the "pusher" units stationed at long/steep up-grades could also use the generator cars to descend back to their sidings, meaning two round-trips for the generators with every train that passes through.