For truck applications the increasing demand for electrical power when the vehicle stands still has led to an increasing need for an on-board electric power generator which operates with high efficiency and very low emissions. A fuel cell based auxiliary power unit (APU), with a diesel fuel processor is regarded as one of the most interesting options since it combines high efficiency, low emissions and the use of the same fuel as the main engine.
The overall objectives of FCGEN were to develop and demonstrate a proof-of-concept complete fuel cell auxiliary power unit in a real application, onboard a truck. However, the vehicle demonstration objective was changed to laboratory demonstration as the project partner, CRF, who was responsible for the vehicle demonstration work package and providing the demonstration truck has left the project after 24 months and it was not possible for the FCGEN consortium to find a suitable replacement for CRF.
The APU system consisting of a low-temperature PEM fuel cell, a diesel fuel processor and necessary balance of plant components will be designed to meet automotive requirements regarding e.g. size, mechanical tolerances, durability etc. High targets are set for energy efficiency and therefore this will significantly lead to emissions reductions and greener transport solutions in line with EU targets. A key point in the project is the development of a fuel processing system that can handle logistic fuels. A fuel processor consisting of autothermal reformer, desulphurization unit, water-gas-shift reactor, reactor for the preferential oxidation of CO, will be developed. The fuel processor will be developed for and tested on standard available low sulphur diesel fuel both for the European and US fuel qualities. Another key point is the development of an efficient and reliable control system for the APU systems including both hardware and software modules. In the final demonstration, the fuel cell based APU will be tested in a laboratory environment as the first step in a defined plan towards Vehicle demonstration.
Novel on-board fuel system for green trucks
Hydrogen as a supplement to diesel in vehicles provides significant advantages in terms of fuel saving. EU-funded scientists are developing fuel cell (FC) technology that could be 85% more efficient compared to internal combustion engines (ICEs) burning hydrogen.
High efficiency and low emissions are the main drivers behind FC systems that can be used as auxiliary power units (APUs) in trucks. However, proton exchange membranes operate more efficiently with hydrogen rather than with the ubiquitous hydrocarbon fuels such as diesel found at gas stations.
In the EU-funded project 'Fuel cell based on-board power generation' (http://www.fcgen.com/ (FCGEN)), researchers have been designing diesel fuel processors to convert hydrocarbons to hydrogen-rich mixtures. The ultimate aim is to integrate them into an FC-based on-board APU to provide highly efficient electric power.
A complex system of reactors, an autothermal reformer, a desulphurisation unit and balance-of-plant (BOP) components are parts of the fuel processor. Catalytic technologies are used for system heating at start-up, fuel reforming and purification, as well as in anode off-gas combustion. Harmful emissions are thus significantly lower than those produced during ICE idling.
The FCGEN project is the first of its kind that seeks to integrate PEM FC-based on-board APU systems. Before testing the system under real conditions, project partners developed a model in a hardware-in-loop set-up to study its dynamic and steady-state behaviour. Furthermore, they purchased and tested BOP components for the complete APU system. For the whole system the complete electric system including power conditioning, BOP power supply and APU electronic control unit were developed, all optimized for FC-based systems and automotive standards.
New generations of reformers, desulphurisation units and reactor systems were tested against system functionality, durability and cost. All catalyst units were optimised to improve thermal stability and avoid poisoning of reactors. Cost-effective fabrication techniques such as embossing, reduction of precious metal loadings in the catalysts and selection of cheaper BOP components will help keep costs down. To enable online testing of the APU and its sub-systems, project partners developed an efficient and reliable control system with comprehensive HMI for support of commissioning stages.
So far the fuel processing has been successfully demonstrated and the system is to be merged with fuel cell stack. Throughout the project all partners have gained an important experience of the tasks required to bring the most recent technology from the laboratory to the real world and make it work, which will be put to good use in future work.
Once completed, this compact and stand-alone system will use low-sulphur diesel fuel to generate clean electricity from the resulting hydrogen. FCGEN findings are expected to provide significant information to vehicle manufacturers, opening the way for wide commercialisation of this new on-board power generation technology.