Environmentally friendly vehicles powered by proton exchange membrane fuel cells (PEMFC) have recently been available to the consumer. The electrochemical energy conversion drive, originally described as a gas battery, uses oxygen in air and hydrogen as a fuel to produce water as the only exhaust product. However, exposure to other substances such as sulfur dioxide emitted by volcanoes and pollutants released by many industries damage the fuel cell. The Hawaii Natural Energy Institute has partnered with the Naval Research Laboratory, UTC Power, Ballard Power Systems, and the University of Connecticut to understand the causes of this damage and develop preventive measures and restoration technologies.

Airborne contaminants were first identified and selected from a pool or more than 200 candidates using a two-steps approach that minimized testing time and cost. As a first step, contaminants were chosen using criteria such as atmospheric concentration (highest concentration preferred) and chemical composition (similar species eliminated). As a second step, a fuel cell was sequentially exposed to all the remaining contaminants to identify those that had the largest detrimental effect on voltage. Subsequently, for the remaining 8 model contaminants, the concentration at which the fuel cell voltage would drop by a pre-determined percentage (tolerance limit) was determined by interpolating fuel cell exposure data obtained with different contaminant concentrations. Tolerance limits are needed to design air filters and maintenance schedules. Finally, sophisticated gas, liquid and solid analysis methods were used to derive molecular level contamination mechanisms and facilitate the development of fuel cell system compatible restoration technologies. Validation tests for 2 restoration technologies are currently ongoing for two types of contaminants, halides (chlorides, bromides) and sulfur oxides (sulfur dioxide), which are respectively important for marine and volcanic environments.

Point Person: Jean St-Pierre

 

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