Options for Static Charging and Dynamic Charging – How to choose?
The choice between the options means a-lot of money in the investment stage, and critical consequences on the operability and economics of the fleet for years to come.
The main options are:
- Depot charging with Plug-in charging stations, and buses equipped with full batteries for operation without charging the full day. This option is heavy initial investment in the buses, but also every several years when the batteries lose their capacity and need be replaced. At the depot, there is an investment in civil and electrical works, and about 6-10% loss of area for the charging stations. Another important factor: The buses carry less passengers due to the batteries weight, so fleet may need extra buses. Plug-in Charging does not support future development for Autonomous transportation or Driverless BRT.
- Depot charging with pantographs plus pantograph stations at certain locations En-route (usually end of route) – the buses need small batteries. Saving in batteries size and cost is calculated against the cost of pantographs and infrastructure at the depot and En-route. Pantographs ease the burden of repeated charging activity from the bus-drivers and save area in the depot. This option will support Autonomous transportation or Driverless BRT.
- Flash charging along the route – multiple flash charging stations along the route are highly expensive due to their large power capacity, and there is still a question about the state-of-health of very fast charged batteries. This option will support Autonomous transportation or Driverless BRT.
- In-Motion-Charging or Dynamic charging presently comes in the form of trolleybus and OCL system (transmission lines above the route). It is a well-established system, that is being revived these days. Modern trolleybuses can have small batteries to cover parts of the routes without OCL system. There is significant investment in installing the infrastructure, but this investment is for decades ahead, and there is over 10% electricity savings vis-à-vis charged batteries buses. Trolleybus
- The Telescopic Current Collector (TCC) of eLinkAir provides better cost-effective solution than any of the previuos options. Each case should be considered specifically, but the inherent price difference between the TCC and the other existing solutions is usually evident. The potential advantages of the Dynamic TCC over existing trolleybus are clear: The TCC is designed to be more flexible than the trolleybus, by being able to leave and return to the electrified road anytime, anyplace. It is more adaptable to Autonomous driving or Driverless BRT.
In-Motion-Charging becomes more and more necessary when the BRT line is very busy, and there are no time breaks during the day in which the buses may recharge. The only other option today for a busy BRT is the first one – Depot charging and heavy batteries for full day operation on each bus. As mentioned above – this is a very expensive option in the short and long run, including necessity to increase fleet size by about 10%. More and more opinions of fleet operators are heard that Plug-in Depot charging alone is not a sustainable solution.
People tend to think wrongly that the infrastructure of overhead lines for IMC is expensive. It is not, if one compares it to an investment in light rail train or tram, and certainly to underground train – for high-capacity lines. Properly designed BRT may carry 40,000 ppdph (there are several good examples for that) and the cost of infrastructure for BRT is a tiny fraction of the competing alternatives.