Railroad wheels and energy generation

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Discussion Overview

The discussion centers on the potential energy generation from a rolling train wheel connected to a generator, exploring various speeds and the optimum velocity for maximizing energy output. Participants compare this scenario to hydroelectric turbines and consider the feasibility of energy harvesting from train wheels.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Rick Thomas Simmons questions how much energy a rolling wheel could generate if connected to a generator and seeks to understand the optimum velocity for energy generation.
  • One participant claims that the wheel would produce about 1/3 of the energy needed to maintain the train's momentum against additional load, suggesting a net loss of 2/3.
  • This participant further argues that the optimum velocity for energy generation would be zero, as it would avoid losses, implying that energy harvesting is generally inefficient.
  • Another participant mentions that regenerative braking has been used in locomotives since 1936, particularly when descending hills, but warns against the idea of generating free energy at constant velocity on level ground, labeling it as perpetual motion.
  • One participant describes scenarios where descending electric trains can assist ascending trains by regenerating power, highlighting practical applications of energy recovery in rail systems.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility and efficiency of energy generation from rolling train wheels. While some acknowledge existing technologies like regenerative braking, others question the overall viability of energy harvesting in this context, indicating unresolved disagreement on the topic.

Contextual Notes

Participants reference various assumptions about energy losses and gains, as well as the historical context of energy recovery in rail systems. The discussion does not resolve the technical feasibility of energy generation from rolling wheels.

Rick Thomas Simmons
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How much energy generation potential would one rolling wheel on a train produce if it was hooked up to a generator if the train is rolling with continual momentum at various speeds. What is the reasonable optimum velocity of the train to maximize energy generation?

How would you figure this out or set up an experiment?
Is it similar to hydroelectric turbine?

Thank You,
Rick Thomas Simmons
 
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Rick Thomas Simmons said:
How much energy generation potential would one rolling wheel on a train produce if it was hooked up to a generator if the train is rolling with continual momentum at various speeds
Typically it would produce about 1/3 of the additional energy that would be spent in keeping the train rolling against the extra load. So a net loss of 2/3.

Rick Thomas Simmons said:
What is the reasonable optimum velocity of the train to maximize energy generation?
The optimum would be zero. No energy would be produced, but the losses would be avoided also. Since the losses exceed the gains, the best you can do is stop.
 
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Dale said:
Typically it would produce about 1/3 of the additional energy that would be spent in keeping the train rolling against the extra load. So a net loss of 2/3.

The optimum would be zero. No energy would be produced, but the losses would be avoided also. Since the losses exceed the gains, the best you can do is stop.
Most Energy Harvesting is a waste of time but the owners of a length of rail track could steal energy from passing trains (fuelled by a different company). But they would have do do this by stealth!
 
Railroad locomotives have been doing that since 1936. They call it regenerative braking (or dynamic braking). It is especially used when going down hill. See https://en.wikipedia.org/wiki/Regenerative_brake

However, if you think that it can be used to get free energy while the train is moving at constant velocity on level ground, that is called perpetual motion, and that topic is forbidden on PF.
 
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There are long steep inclines where a loaded electric train needing to ascend the incline has been required to do so while a train on a parallel line is descending, so that the regenerated power pushed into the overhead conductor by the descending loco can aid the ascending loco. When a descending train is not available, a diesel loco can be brought into provide the extra grunt.
 

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