The fuel cell (FC) is seen as an autonomous energy source on board rail-based vehicles (trams and locomotive tractors) and buses. An FC on board this kind of vehicle can only be used in combination with an Energy Storage System (ESS) such as a battery, super-capacity battery or flywheel.
The questions at issue are :
- Choice of fuel and storage technologies
- Availability and maturity (reliability, life etc.) of FCs
- Optimal method of managing FCs for transport
- Optimal vehicle energy management
- Constraints related to installing FCs and storing fuel on board a vehicle
- Comprehensive modelling and simulation of hybrid vehicles with FCs
- Test bed for digital simulation models of hybrid vehicles with FCs
The aim of the COPPACE project is to identify the technologies and best choice of FC/ESS combination for use in locomotive tractors and buses.
PREDIT - working group no. 10
The work was divided up as follows: ·
* The French Atomic Energy Commission (CEA) studied the types of fuel (hydrogen and others) and their on-board storage technologies (pressurised, cryogenic, metal hydrides),
* The Enseeiht worked on the FC sub-system and its auxiliary features: fuel cell stacking, air and fuel supplies and control/command.
* Alstom Transport defined the requirements and constraints for using FCs. It also carried out vehicle simulations, produced the industrial test bed and was responsible for project management. Optimisation work was carried out with an American laboratory.
agreement 01 MT 07
Types of fuel and storage :
* Hydrogen is the most suitable fuel with pressurised storage (optimally 500-600 bars)
Component modelling and scaling :
*FC: detailed dynamic physical model produced by the CEA.
*FC: behavioural model (based on a simplification of the CEA physical model) and associated command system (multiple variables and uncoupling). At the end of the project (January 2004), FC technology was not felt to be sufficiently mature (life, price, industrial supply, etc.) to envisage the applications in question becoming a reality in the very short term.
* Power converters
- Development of a monodirectional step-up transformer chopper for FC
- Development of a bidirectional step-up/step-down transformer chopper for ESS.
* ESS Development of electrical, thermal and mechanical models (mass and volume usable on board) for different Energy Storage Systems: batteries, super-capacity batteries and flywheels. Batteries do not seem to be the best storage method as the FC is itself an energy source. Super-capacity batteries and flywheels are better suited to these applications. An ESS comprising two different technologies (e.g. a flywheel and a super-capacity battery) would meet the ESS's energy and power requirement perfectly.
* Vehicle models and usage cycles:
Installation of Advisor software for hybrid vehicle simulation. Development of FC and ESS models and several energy strategies making it possible to:
- define the scale of traction chain components,
- optimise the choice of ESS technologies and the choice of energy strategies and settings based on comparisons of traction-chain configurations examined on different usage cycles for buses, trams and locomotive tractors.
* Energy strategy.
The project demonstrated the following points
- the energy strategy serves the technical and/or economic target defined for the vehicle (e.g. minimising consumption, minimising maintenance or acquisition costs). As a result, numerous energy strategies are possible.
- The optimal energy strategy also correlates with the ESS technology adopted.
Trial methods and trials
* Design and construction of an FC test bed and hybrid traction chain. The bed can be used to test FCs with very high power levels (up to 200 kW) and to trial ESSs on traction chains with unlimited power levels (e.g. 900 kW tramway).
* Acquisition and trial of a super-capacity pack (450 kW; 0.55 kWh). These trials were used to confirm simulated electrical, thermal and mechanical performance. ·
* Test regime on the Lyon tramway. These trials were used to validate the vehicle simulations produced with Advisor and confirm vehicle use hypotheses in current commercial operation.