Fuel cell a useful complement to battery-electric drives, study says
Politicians and industry are in broad agreement that the CO2 emissions caused by the transport sector must be significantly reduced. To achieve this goal, however, the public and political debate is largely focused on the battery-electric drive, complains Matthias Kratzsch, Chairman of IAV’s Board of Management. At the highly respected Vienna Motor Symposium, the engineering company therefore presented a study showing that it would make perfect sense to include hydrogen fuel cell drive more strongly in the development of environmentally friendly mobility. This applies above all to heavier vehicles.
For the study, experts from IAV examined the CO2 footprint of three vehicle classes. These were a medium-heavy SUV, a light commercial vehicle and a heavy commercial vehicle. For each vehicle class, the study authors examined the CO2 equivalents that would be produced by using a purely battery-electric drive, a fuel cell and a hydrogen combustion engine. The calculations were made according to a tank-to-wheel, well-to-wheel and life cycle assessment (LCA). For the latter, the complete cycle of a vehicle was analysed from raw material extraction through the logistics chain, production, assembly and use to recycling.
For their work, the authors used GaBi, the leading LCA software in the automotive sector, and applied data from the German Federal Environment Agency (UBA), for example for the predicted CO2 intensity of the German electricity mix in 2030, taking into account the progressive trend in the German automotive industry towards CO2-neutral production as well as increasing production of battery systems.
With all three drive variants examined, the CO2 footprint in the transport sector could be significantly reduced in 2030 under consistent LCA consideration, explains study author and IAV department head Marc Sens. According to the results, a vehicle with a fuel cell drive is, depending on the vehicle class examined, similarly climate-friendly to a purely battery-electric vehicle in the respective weight class.
The study also examined the suitability of a drive concept in which hydrogen is used directly as a fuel in modified conventional combustion engines. This involves burning hydrogen instead of conventional petrol – a principle that is practically no longer relevant today. BMW had experimented with this drive a good ten years ago, but discontinued these trials as not achieving their goals. The IAV study showed, however, that direct hydrogen combustion could be positively assessed from the point of view of CO2 reduction. As advantages of the hydrogen combustion engine, the study names high robustness and rapid transferability to series production. Due to its low efficiency, however, this technology does not come close to the fuel cell drive – which, for its part, is also criticised for its significantly poorer overall efficiency compared to the battery-electric principle.
The potential of the drive technologies examined becomes particularly clear when they are considered in the context of current CO2 legislation. According to this legislation, new passenger cars registered in the EU may not currently exceed an average target of 95 g CO2/km. The EU’s calculation method is based on the tank-to-wheel perspective and thus excludes major CO2 sources such as raw material extraction, production and recycling. The study now available shows that using purely battery-electric as well as hydrogen-based drives and production and recycling processes that are as CO2-neutral as possible in the passenger car sector, a value of just over 70 g CO2/km could even be achieved over the entire life cycle.
“Even in vehicle classes such as light commercial vehicles, significant CO2 savings potentials are possible by 2030 under LCA considerations. According to our calculations, the fuel cell (132 or 117 g CO2/km) is even slightly superior to the battery-electric drive (139 g CO2/km) due to the battery size required for the target range of 500 km,” says Sens.
From an LCA point of view, there is also significant CO2 savings potential for heavy commercial vehicles with all drive variants. Regardless of the higher production costs and a necessarily more potent charging infrastructure, the battery-electric drive in the heavy-duty sector plays out its potential particularly well over the entire life cycle. Due to the long mileage of trucks, the CO2-intensive raw material extraction for battery systems is far less significant here than in other vehicle classes, which is why the CO2 footprint of the battery-electric drive in the route-specific LCA consideration falls to 126 g CO2/km in the best case.
Study leader Sens: “Our results show the great CO2 savings potential of hydrogen and battery-electric drive systems in an honest life cycle assessment. However, it is also clear that a significant CO2 reduction in the transport sector can only be achieved with the rapid expansion of renewable energy production, both for the cleanest possible electricity and hydrogen production and for consistent use in all phases of the vehicle’s life cycle.”
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