Editing Dynamic braking (section)

==Regenerative braking==
{{Main article|Regenerative brake}}
In [[railway electrification system|electrified systems]] the process of [[regenerative braking]] is employed whereby the current produced during braking is fed back into the power supply system for use by other traction units, instead of being wasted as heat. It is normal practice to incorporate both regenerative and rheostatic braking in electrified systems.  If the power supply system is not ''"receptive"'', i.e. incapable of absorbing the current, the system will default to rheostatic mode in order to provide the braking effect.

Yard locomotives with onboard energy storage systems which allow the recovery of some of the energy which would otherwise be wasted as heat are now available. The [[Green Goat]] model, for example, is being used by [[Canadian Pacific Railway]], [[BNSF Railway]], [[Kansas City Southern Railway]] and [[Union Pacific Railroad]].

On modern passenger locomotives equipped with AC [[Inverter (electrical)|inverter]]s pulling trains with sufficient [[head-end power]] (HEP) loads, braking energy can be used to power the train's on board systems via regenerative braking if the electrification system is not receptive or even if the track is not electrified to begin with. The HEP load on modern passenger trains is so great that some new electric locomotives such as the [[ALP-46]] were designed without the traditional resistance grids.