Cars with fuel cell

Reading time: approx. 3 minutes – In the second and final part on the subject of fuel cells, we look at the opportunities that cars with fuel cells could have in the future. We also consider what efforts are required to achieve this.

At the end of the 19th century, Tesla, Westinghouse and Edison engaged in a so-called electricity war. Due to several decisive advantages, Tesla and Westinghouse were able to prevail in this conflict with alternating current technology. Thus, a long-lasting era of this type of energy supply began. Now, almost 125 years later, the German Federal Ministry for Economic Affairs and Energy has been funding a cross-sector research project called “DC Industry” since 1 July 2016. The aim of this project is to convert the energy supply in industrial production to direct current using DC-DC voltage converters. Such a changeover affects not only the supply networks. It also impacts the power electronics in industry to the same extent. The advantages and disadvantages of both types of supply are analysed below. The resulting consequences for consumers are also considered.

Reasons for switching to DC-DC voltage converters

When choosing a suitable power supply, a distinction must be made between two separate requirements. The transfer of energy from the generator to the consumer and the functioning of the consumers.

High voltages are required to transport the electricity over long distances with as little loss as possible. In the past, it was only possible to adjust the voltage economically with alternating voltage. However, transporting energy using alternating voltage leads to losses depending on the distance and the necessary insulation. These losses are due to the capacitive and inductive properties of the line. These properties lead to a constantly occurring reactive current that depends on the AC frequency and the length of the line. Furthermore, the so-called skin effect results in charge carriers moving more on the surface of the conductor due to the high frequency. Therefore, thicker cables are required than for a comparable DC transmission. This provides the current with a larger conductor surface.

With a few exceptions, the major German car manufacturers are currently focussing on battery electric vehicles when switching to regenerative drive systems. Asian manufacturers in particular now offer an alternative concept. It consists of a hydrogen tank in combination with a fuel cell stack. A car with a fuel cell is still a very rare sight on the roads today. As in a battery electric vehicle, the electrical energy released is fed to the electric motor by means of an inverter. Alternatively, it is fed to the 12V vehicle electrical system by means of a DC/DC converter. The time-consuming and usually impractical battery charging times are no longer necessary. Refuelling with hydrogen, in terms of duration and effort, is in no way inferior to refuelling with fossil fuels.

The challenge: Appropriate infrastructure

The dangers posed by hydrogen in the event of accidents or breakdowns during refuelling can also be regarded as rather unproblematic. This is because hydrogen, unlike petrol vapours, volatilises very quickly due to its extremely low density. The greatest challenge in enabling the widespread use of cars with fuel cells lies in the creation of an appropriate infrastructure. The costs for this are immense due to the demanding storage of hydrogen. Additionally, the development of a charging network for batteries adds to the overall expense.

Cars with fuel cell as a genuine innovation

Recently published research results concerning the catalyst material of fuel cells give hope that manufacturing costs will soon fall. Attempts are being made to replace the expensive platinum catalyst element previously used in membrane fuel cells. These attempts involve using cheaper materials such as tantalum and niobium disulphide. Furthermore, advances in the hydrogen production process are also attributable to improved catalyser properties. These improvements will enable a significant increase in efficiency. Problems associated with storing hydrogen, caused by diffusion of the gas, were significantly reduced a few years ago. This was achieved thanks to specially coated tanks.

In addition to the size and weight of the cells, it has also recently been possible to continuously optimise their operation in terms of susceptibility to faults. This makes their use in private and large-scale production applications appear economically viable.

Conclusion

This technology, which was almost forgotten for a long time, has great potential to help shape the move away from fossil fuels and decentralised energy supply. The greatest challenge lies in creating a high-performance infrastructure. This will incur immense costs in addition to the growing network of charging points. However, these investments are unavoidable in view of the fact that an urgently needed energy transition cannot be achieved with a single technology. These investments must be made to ensure progress.