Team from Daimler, ZBT, Jülich finds impact of air pollution on fuel cell power and lifetime “significant”
Traffic-related air pollutants can lead to a short-term loss of power and long-term reduction in lifetime for proton exchange membrane fuel cells (PEMFC). However, while research has been carried out on the reaction mechanisms, the impact of this for vehicles has not been studied extensively under real-world conditions.
A team from Daimler, ZBT GmbH and Forschungszentrum Jülich has now systematically analyzed the influence of NO, NO2, NH3 and SO2 on automobile fuel cells under realistic conditions. In total, more than 12 fuel cell stacks accumulated a total of more than 2500 h with four air contaminants. In a paper in Journal of Power Sources, the researchers report that the negative affects can be significant.
Among their findings were that spontaneous power losses of about 5% and more than 10% in special situations from NOx can be expected for fuel cell vehicles in urban areas. NH3 will lead to a spontaneous power loss of less than 3%, but causes a progressive irreversible damage, shortening lifetime.
Together the tests reveal that air pollutants have a significant negative influence on fuel cell vehicles in urban areas.—Talke et al.
For the study, they used two different types of fuel cells—high and a low platinum loading—in automobile short stacks with ten cells each. Four stacks were always tested in parallel in a four-stack test bench to ensure best comparability of the results.
The operating conditions were selected in such a way as to be in the range of the conditions used in fuel cell vehicles.
First, four stacks were tested for more than 1500 h in a semi-dynamic way with different air contaminants. In these tests, only one of the relevant operating parameters such as the temperature or the pressure was dynamically varied while the other parameters were fixed at a medium level.
In a second set of tests, a real driving cycle gained from an existing course near Stuttgart, Germany was used to create full-dynamic tests. Four stacks of high-platinum-load fuel cells were tested for 365 h; four stacks of the low-load type were tested for another 716 h.
In summary the present study therefore combines fuel cell tests under automotive conditions, long testing times and real contaminant concentration measurements on the streets for the first time. By combination it could be shown, that all tested pollutants—NO, NO2, SO2 and particularly NH3 will have a significant negative influence on fuel cell vehicles in Germany. It may also be assumed that other pollutants, such as hydrocarbons, have a negative influence on fuel cell vehicles, too. For this reason further research and development regarding sui- table filters and operating strategies against the negative influence of air contaminants are suggested.—Talke et al.
Anja Talke, Ulrich Misz, Gerhard Konrad, Angelika Heinzel, Dieter Klemp, Robert Wegener (2018) “Influence of urban air on proton exchange membrane fuel cell vehicles – Long term effects of air contaminants in an authentic driving cycle,” Journal of Power Sources Volume 400, Pages 556-565, doi: 10.1016/j.jpowsour.2018.08.063