In order to achieve climate protection goals, the transportation sector must drastically reduce the greenhouse gas emissions caused by the use of fossil fuels, Fraunhofer ISE pointed out. (photo above © Fraunhofer ISE / Guido Kirsch)
However, how big are the GHG emissions of alternative propulsion concepts?
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE conducted a life-cycle comparison of electric and fuel cell vehicles. The study was commissioned by H2 Mobility Deutschland.
In the Fraunhofer ISE study, vehicles with fuel cell technology performed better in terms of greenhouse gas emissions than battery-powered vehicles.The study investigated greenhouse gas (GHG) emissions in the manufacturing, operation, and disposal of battery and fuel cell vehicles with ranges from 300km for the periods 2020-2030 and 2030-2040. Various scenarios were considered for the generation of electricity or hydrogen.
The power for the battery vehicles comes at best from the photovoltaic system, while the German electricity mix represents the worst case. For the hydrogen supply, for example, the generation using electrolysis with wind power (Best Case) and the natural gas steam reforming (worst case) were used.
In addition, both technologies were compared to a car using fossil diesel fuel.
They found that at 150,000 kilometers, even in the worst-case scenario, the GHG emissions of the hydrogen fuel cell vehicle are below those of comparable battery vehicles (90kWh battery), which are powered by the German electricity mix.
Furthermore, as expected fossil diesel vehicles have higher GHG emissions.
The study also reveals that battery and fuel cell vehicles complement each other ideally, noted Christopher Hebling, Head of Hydrogen Technologies at Fraunhofer ISE. For long distances, fuel cell vehicles are more climate-friendly and for short distances battery-powered vehicles, according to Hebling.
For example, in the period 2020-2030, the study projected that fuel cell vehicles will have a better GHG footprint than battery vehicles with a battery capacity greater than 45kWh.
The study was quite comprehensive in making projections and forecasts for the technology.
They forecast the technology improvement in batteries for EVs including the battery cell structure, the anode, the cathode, the membrane, etc…. and each components contribution to the GHG emissions. Again they formulated a base case, as well as a best and worst-case scenarios for the battery technology combination for 2020, 2030, and 2040. They predict the biggest improvement in battery technology will be in the battery cell structure.
They also made predictions about the improvements in hydrogen fuel cell technology. They had a separate set of projections about the decreasing need for platinum in hydrogen fuel cells.
They expect the biggest improvements in hydrogen fuel cell technology to be the catalyst used along with electrolysis to extract hydrogen from water. They also predict significant decreases in how much platinum is required.
- Greenhouse gas (GHG) emissions Fuel cell vehicle lower than for considered Battery vehicles (60kWh and 90kWh battery capacity)
- Critical factors for battery vehicles: cell production and GHG footprint electricity
- Crucial factors for fuel cell vehicle: platinum and H2 -Tank
Overall view :
- Period 2020-2030: GHG emission advantages of the fuel cell vehicle
- Greater efficiency of battery vehicle operation does not compensate for the GHG disadvantage from its production
- Production of hydrogen by means of wind power → path with lowest emissions
- Period from 2030 to 2040
- At comparable range, fuel cell vehicle has GHG emission advantages , if both vehicles use renewable electricity
- Battery vehicles with lower battery capacity / range (approx. <50kWh / 250km) offer GHG emission advantages over fuel cell vehicles.
- There was no potential for improvement in the production of materials (platinum, aluminum, etc.) considered
- Novel H2 -Tank concepts could not be considered in the study
Areas where future study is needed:
- In addition to GHG emissions, other impact categories should be investigated (Area consumption, water consumption, etc.)
- Environmental impact for the construction of the mobility infrastructure was not considered (Charging infrastructure, H 2 Distribution, etc.)
- Systemic aspects / interaction with energy system should be investigated more closely
- Consideration of further drive concepts necessary (eg hybrid, internal combustion engine with synthetic fuels)
- No consideration of second-life aspects for battery and fuel cell
- No GHG credit for materials after disposal
Beyond the study, we see further research needs, such as the use of synthetic fuels, which are produced from hydrogen from renewable energies and CO2 , as second-life aspects or the effects on surface and water consumption, project manager Dr. Ing. André Sternberg noted.
Sternberg, A., Hank, C., and Hebling, C., Public Greenhous Gas Emissions for Battery and Fuel Cell Vehicles with Reached over 300 KM. Fraunhofer ISE, published July 13, 2019.