How Useful Are Renewable Energies in the Mobility Sector?

Advantages and disadvantages of hydrogen and electric drives in the mobility sector.

CO2 emissions are emitted in all sectors but the sectors contribute to CO2 pollution to varying degrees. According to the Federal Environment Agency's climate balance sheet, with 163 million metric tons of CO2 equivalents, the transport sector forms the third place in the ranking of total greenhouse gas emissions in Germany in 2019¹. This means that the transport sector is a major contributor to greenhouse gas emissions. What changes need to take place in the transport sector to reduce emissions and enable Germany to meet its climate target of reducing CO2 emissions to 65% by 2030? For a long time now, the expansion of the e-mobility segment has been on the rise in the transport sector and among the major car manufacturers. Hybrid cars, pure electric cars or hydrogen-powered vehicles, all these solutions for lower CO2 emissions and a better climate footprint are hotly debated. However, which of these inventions has the most potential to win over the vehicle market?

Hydrogen is not “naturally” green.

The camps are deeply divided. According to the German Federal Ministry for the Environment, hydrogen and synthetic fuels are more expensive than battery powered cars. This is mainly due to the production of the fuel. More energy has to be used for the production of hydrogen or other synthetic fuels than for the production of an electric drive. In addition, the electric cars have the better more efficient balance, insofar as the e-fuels do not come 100% from renewable energies. Moreover, that leads to the next problem, the extraction and production of different fuels. Hydrogen is not “naturally” green. So-called gray hydrogen is produced from fossil fuels. It is most frequently produced from natural gas. This process currently accounts for 98 percent of global production². The energy sector is not as good developed as the entire vehicle industry can switch to fuels from renewable energies. It takes significantly more energy to produce these fuels than it does to manufacture and use electric motors. So to produce green hydrogen, Germany has to import from abroad. Of course, this involves many risks as well as difficulties. The transport alone will be a challenge. Electricity from renewable energies or hydrogen from other regions of the world are both challenging visions for the future. In contrast to the electricity that is currently generated from coal-fired power plants, however, both approaches, hydrogen and electricity from renewable energies, offer an important step towards a climate-friendly future. Synthetic fuels, on the other hand, still require the internal combustion engine, which is significantly more inefficient in the long term than hydrogen-powered cars or e-cars.
However, couldn't hydrogen and fuel cells be used in combination? Experts at the Fraunhofer Institute answer this question with yes. However, they see this combination more likely in long-distance and heavy-duty transport, as well as in rail, air, and shipping.

Are Batteries Suitable for Long-Distance Transport?

The transportation sector is a major contributor to climate change. Here, too, the first development steps have already been taken toward pure e-trucks. This does not seem to be a problem for 18-ton trucks. The rest breaks of the truck drivers can be used for intermediate battery charging and the size as well as the weight of the trucks does not seem to be an excessive demand for the electric drive. Challenges of various kinds arise with heavy trucks in long distance replanishment with for example 40-ton trucks, since here an 8-ton battery has to be carried along and the legally mandatory breaks of 45 minutes and charging infrastructure might not be sufficient for charging.
Another advantage of e-mobility in the transportation sector is the low noise level e-trucks generate. Therefore, some experts from the Karlsruhe Institute of Technology (KIT) see only the battery as a solution for long-distance traffic. But here, too, opinions differ. Other KIT experts do not see batteries as suitable for long-distance transport due to its short range. They suggest the fuel cell as an alternative for long-distance transport on an e-plattform. However, practical experience is still lacking, especially with regard to the reliability and service life of the cells, but ultimately these are development tasks that can be solved.
This discrepancy shows that further research and practical experience is needed. To enable participants to form their own opinions, lecturers of different opinions teach in the HECTOR School programs.

There is no Clear Winner Here

The fuel cell is considered significantly more inefficient than the battery. Only about 1/3 of the energy reaches the wheel. The battery has an efficiency of 70-80%³ while hydrogen has only 25-35%. 45% of the energy is already lost when hydrogen is produced by electrolysis. Of this remaining 55% of the original energy, another 55% is lost when hydrogen is converted into electricity in the vehicle. For the sake of completeness, the efficiency of alternative fuels is even worse. The overall efficiency here is only 10 to 20%⁴.
In addition, there are the acquisition costs, which according to BOSCH are currently three times higher for a fuel cell unit than for a diesel engine. However, this is expected to change by 2030 due to higher production figures and the rising price of diesel, reversing the ratio⁵.
However, the fuel cell does not only have disadvantages. Refueling hydrogen works faster than charging an electric vehicle. As long as the hydrogen is produced sustainably, fuel cell vehicles are emission-free. Hydrogen cars can travel up to 650 kilometers on a single tank of fuel, which, as things stand today, is only possible with electric cars from the most expensive manufacturers, such as Tesla or Mercedes Benz⁶. So there is no clear winner here. In addition, the energy sector and the infrastructure must be further expanded in both cases in order to enable a cost-effective and convenient driving experience for the end user.

Effective Use of Data

Another challenge in the transformation of the transport sector is the new technologies installed in the vehicles. Simulations and standardized rules and processes for the smooth use of electronic components in vehicles are currently at the forefront of development. Scientific projects such as the Software defined car with partners from science (KIT, Uni Stuttgart) and industry (BooleWorks GmbH, Bosch, Vector Informatik GmbH, Mercedes Benz AG, ZF Friedrichshafen AG, etc.) are developing new methods and processes for the car of the future and its effective use of data.

New Technologies in the Automotive Industry Are on the Rise

New technologies in the automotive industry are on the rise in the wake of the energy transition. The HECTOR School´s part-time Master of Science in Mobility Systems Engineering and Management program covers topics such as alternative drivetrains and the political framework of e-mobility. The Master’s program thus combines the traditional methods of the automotive industry with the new, energy-efficient and innovative perspectives. Therefore, graduates are prepared not only for current trends, but also for future changes.

¹ https://www.bmu.de/fileadmin/Daten_BMU/Pools/Broschueren/klimaschutz_zahlen_2020_broschuere_bf.pdf, page 26.

² https://www.handelsblatt.com/unternehmen/industrie/automobilzulieferer-bosch-macht-elektroantriebe-zum-kerngeschaeft-milliardeninvestition-in-brennstoffzelle/27120678.html, page 16

³ https://www.handelsblatt.com/unternehmen/industrie/automobilzulieferer-bosch-macht-elektroantriebe-zum-kerngeschaeft-milliardeninvestition-in-brennstoffzelle/27120678.html, page 46

⁴ https://www.mooncity-salzburg.at/journal/was-ist-effizienter:-e-batterie-oder-wasserstoff

⁵ https://www.handelsblatt.com/unternehmen/industrie/automobilzulieferer-bosch-macht-elektroantriebe-zum-kerngeschaeft-milliardeninvestition-in-brennstoffzelle/27120678.html, section 4.

⁶ https://www.mdr.de/wissen/wasserstoff-batterie-elektroauto-vergleich-vorteile-nachteile-100.html, section 4

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