Electricity created by dynamic braking fed back into US grid?

[TucsonRailFan]

Has the electricity that is created during dynamic braking been fed back into the US power grid? I guess it would have to be done with an overhead wire on the downhill sections ???

How about electrified trains that already are fed thru the above wire? Does this power come from dedicated power plants? If not, could the power generated by dynamic braking be fed back into the grid via the existing overhead wire?

A long heavy freight train at the top of an ascent seems like a LOT of potential energy that is wasted.

 

[speeder3]

Has the electricity that is created during dynamic braking been fed back into the US power grid? I guess it would have to be done with an overhead wire on the downhill sections ???

How about electrified trains that already are fed thru the above wire? Does this power come from dedicated power plants? If not, could the power generated by dynamic braking be fed back into the grid via the existing overhead wire?

A long heavy freight train at the top of an ascent seems like a LOT of potential energy that is wasted.

For diesel-electric locomotives with dynamic braking, there is no physical way of transferring the current generated by the traction motors to the US power grid, as you put it. There would have to be a physical connection between the locomotive and power lines running parallel to the track.

However, in the case of electric locomotives, such as those that operated on the GN and Milwaukee Road through the Rockies and Cascades, on descending grades the current generated by the traction motors was in fact fed back into the overhead catenary.

Brian

 

[TucsonRailFan]

There would have to be a physical connection between the locomotive and power lines running parallel to the track.

Brian

I was just wondering if the physical connection had ever been set up on any long downhill runs. I realize it would be an expensive endeavor. Thanks.

Maybe cars of storage batteries could be used and then converted to A/C and drained off into the grid at certain stops.? Or the batteries could be used to help power the train, allowing the diesel engines to not have to work so hard? Or maybe the weight of the additional cars would completely defeat the purpose?

 

[robjacox]

I was just wondering if the physical connection had ever been set up on any long downhill runs. I realize it would be an expensive endeavor. Thanks.

Maybe cars of storage batteries could be used and then converted to A/C and drained off into the grid at certain stops.? Or the batteries could be used to help power the train, allowing the diesel engines to not have to work so hard? Or maybe the weight of the additional cars would completely defeat the purpose?

If the initial cost and complexity of installing overhead wires wasn't an issue, we would certainly have more electrified lines.

If a locomotive had enough onboard storage capacity to contain dynamic braking power and "recharge" the grid, it would instead just use that power to power itself. GE has a hybrid ES44 testing this concept.

Fortunately the railroads have yet to invest billions to save a few hundred thousand dollars and say "look at me - I'm green!".

 

[TucsonRailFan]

If the initial cost and complexity of installing overhead wires wasn't an issue, we would certainly have more electrified lines.

If a locomotive had enough onboard storage capacity to contain dynamic braking power and "recharge" the grid, it would instead just use that power to power itself. GE has a hybrid ES44 testing this concept.

Thanks for the info.

Fortunately the railroads have yet to invest billions to save a few hundred thousand dollars and say "look at me - I'm green!".

Honestly, I wasn't trying to start a political discussion. I don't discuss religion or politics online. I was just curious as to the science/engineering behind it and the feasibility.

 

[kenw]

It's a worthy question, however I think the reality of the costs would kill it. The older electrified railroads did do this, feeding the braking-generated power back into the overhead lines for use elsewhere. But it was their railroad AND their power system, so all the control was in their hands.

Here’s some of my thoughts:

A big issue is matching the line conditions of voltage and frequency. If you feed AC into an AC line, the frequency has to match precisely or it really gets things screwed up. Not just in frequency (like 60Hz), but also they must match peak-for-peak. That adds some complexity to the operation, increasing costs and raising the break-even point. Feed-in rates for public utilities are pretty awful in reality, and most folks who do it on relatively small scales never reach the break-even point. To do it with regular diesel-electric now would mean that the tracks would now have to have power lines following them 100% of the way, and that’s a huge cost.

If the lines aren’t constantly alongside, the locomotive would have to store the juice somehow and then dump it when it could. Storage of electricity (batteries, etc) is woefully expensive and just creates more weight creating less overall efficiency. $$$

At this point, the voltage of what is generated and what is carried on power lines doesn’t match and someone is going to have to provide a means to make the match. And in most cases, that cost falls on whoever wants to sell the power to the utility, not the utility. So now each locomotive needs to either be converted to match or have conversion equipment installed. More $$$$. I’m not sure but IIRC, locomotives generally operate on 72 volt systems, you’ll need to get it to at least 240 to match the basic utility power distribution system. In remote areas those high power lines can be 10000v + and DC to boot.

I like to wonder what-if sometimes. It doesn't always result in an earth-shattering revelation, but it keeps the brain cells functioning.

 

[TucsonRailFan]

Thanks Ken! I'm a novice and I was just thinking along the line of physics, potential and kinetic energies, and realized that a fully loaded freight train at the top of an ascent is a LOT of potential energy that could be harnessed.

Just thinking out loud. Not trying to irritate the old-timers with my novice questions.

 

[maersksealand3329]

IIRC Amtrak's AEM-7's and the Acela send power back to the grid in dynamic braking. I could be wrong on that though.

 

[litz]

Frequency and peak matching isn't as hard as you think it is ... generators do it automatically all the time when latching onto, and off of, the grid.

 

[kenw]

Didn't say it was hard just important to consider. It isn't just 'hookin' 'em up'

 

[litz]

Now that's the God's honest Truth ...

At the power levels under consideration here, making a mistake when attaching to the grid would be ... at best -- spectacular ... at worst -- super spectacular (we're talking "Modern Marvels Engineering Disasters" level)

 

[brad_in_omaha]

IIRC Amtrak's AEM-7's and the Acela send power back to the grid in dynamic braking. I could be wrong on that though.

I know the Acela does put it back in the system. Saw it on the History Channel. I think it was on "Modern Marvels".

 

[kenw]

Now that's the God's honest Truth ...

At the power levels under consideration here, making a mistake when attaching to the grid would be ... at best -- spectacular ... at worst -- super spectacular (we're talking "Modern Marvels Engineering Disasters" level)

yes, but in reality the connection to the grid would be in a single or relatively few places: wherever the catenary connects to draw power would be the same place it pushes it back. That would mean that each locomotive doesn't have the expense to do it directly and reduce costs significantly. This works well in dense areas such as the NE corridor, but in northern Montana, stringing catenary is a huge expense, let alone keeping ice off, etc. The value of the returned power would never offset the cost of just maintaining the lines, let alone the original installation costs.