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Optimisation of Hydrogen-powered Internal Combustion Engines

The overall goal of HyHEELS is to provide an UltraCap energy storage system for the use in hybrid- and fuel-cell vehicles, which satisfies all the properties necessary to make an integrative component.

Tags: Road


While the deployment of fuel-cell cars in the European fleet will take decades (it normally takes more than 20 years for standard functions to reach a 90% fleet penetration), CO2 problems are present and demanding; the automotive industry favours solutions offering future potential when coupled with innovative powertrains as well as with the possible realisation of short-term benefits in combination with state-of-the-art powertrain technology.

In this regard, it is necessary to stress the fact that automotive technology has grown to be more and more complex in recent years by the addition of an increasing number of functionalities. OEMs addressed this challenge by decreasing the production of in-house parts and by the supply of black box-like system components, the integration of which still constitutes a big challenge in terms of handling complexity. This is why the HyHEELS consortium considered it to be appropriate to focus on providing an UltraCap storage function comprising all the properties necessary to make it an integrative component. This is the unanimous view of both the supplier and the OEM regarding manageable interfaces.


The detailed scientific and technical objectives are the result of a thorough analysis of the challenges in the energy supply architecture of hybrid and hydrogen fuel-cell vehicles. A hydrogen fuel cell has to be provided with power and energy during the start-up phase as well as continuously during operation. High power is needed for the acceleration of the vehicle and for high power auxiliary fuel cell loads like the compressor. A powerful and reliable energy supply is crucial to fulfil the requirements of the future passenger car generation, which will be powered by hydrogen fuel cells.

These could have high-power charge and discharge conditions as well as operating at low temperature, e.g. -20°C. UltraCaps could fill the power gap. The approved UltraCap storage technology is available but needs to be adapted to future automotive hybrid and hydrogen applications, satisfying the demands on cost efficiency, safety and reliability.

Description of work

The aim of the development is to provide an improved cost-efficient energy supply concept for hybrid vehicles based on an advanced, powerful UltraCap. This will be achieved by:

  • increasing the maximum operating voltage of UltraCaps from 2.5V to 2.7V. High-cell voltage requires an electrochemical stability of the electrode, the electrolyte and the packaging materials
  • cost reduction of the electrodes by new production technologies
  • cost reduction of cells and modules by industrialisation
  • advanced UltraCap component electrode and packaging. All the materials need to have a high electrochemical stability in order to operate the components at a higher voltage over a longer period of time. The component packaging weight must be minimised. Special attention must be paid to the packaging tightness and to the mechanical resistance
  • advanced UltraCap module packaging with optimised thermal behaviour, weight and cost
  • development of an UltraCap controller, including a single cell voltage measurement and cell balancing, providing extended UltraCap information to the fuel-cell system supervisor.

The final goal of the project is the installation of an advanced, reliable and cost-efficient UltraCap module, providing all necessary information, which enables the integration into the fuel-cell vehicle architecture.


The contribution of HyHEELs to societal and policy objectives cannot be regarded in isolation but have to be seen in combination with the vehicle for which it delivers the energy supply. HyHEELs-developed Ultracaps are a necessary prerequisite for the development and validation of a hybrid vehicle with a vision to achieve

  1. ‘well to wheel’ energy efficiency exceeding 35% on the extended European urban drive cycle,
  2. ‘tank to wheel’ CO2 emissions not exceeding 80g/km when fuelled by hydrogen derived from fossil-based fuels and
  3. near zero CO2 and pollutant emissions when fuelled by hydrogen produced from renewable sources.