FCV Learning Demonstration: Project Midpoint Status and First-Generation Vehicle Results (Presentation)
The “Controlled Hydrogen Fleet and Infrastructure Demonstration and Validation Project,” also known as the Fuel Cell Vehicle and Infrastructure Learning Demonstration, is a 5-year U.S. Department of Energy (DOE) project started in 2004. The purpose of this project is to conduct an integrated field validation that simultaneously examines the performance of fuel cell vehicles and the supporting hydrogen infrastructure. Four industry teams are currently operating more than 77 vehicles and 14 refueling stations, with plans to add over 50 additional vehicles and several additional refueling stations during the remainder of the project duration. This paper covers the progress accomplished by the demonstration and validation project since inception, including results from analysis of six months of new data. With three sets of public results having been presented previously, this paper comes at roughly the mid-point of the project, just as second-generation fuel cell stacks and vehicles are being introduced and some early vehicles are being retired. With many fuel cell stacks having accumulated well over 500 hours of real-world operation, there is now a higher level of confidence in the trends and projections relating to the durability and voltage degradation of these first-generation fuel cell stacks.Public results for this project are in the form of composite data products, which aggregate individual performance into a range that protects the intellectual property and the identity of each company, while still publishing overall status and progress. In addition to generating composite data products, NREL is performing additional analyses to provide detailed recommendations back to the R&D program. This includes analysis to identify sensitivities of fuel cell durability to factors such as vehicle duty cycle, number of on/off cycles, time at idle, and ambient temperature. An overview of this multivariate analysis and preliminary findings will be shared, with future project activities discussed.
Analysis of trace impurities in hydrogen: Enrichment of impurities using a H2 selective permeation membrane ☆
Abstract A laboratory-scale gas sampling and impurity enrichment device (GSIED) using a Pd/Cu-coated Pd–Ag alloy hydrogen selective permeation membrane has been designed, fabricated, and tested to show that such a device provides an effective method to enrich trace impurity species in hydrogen by factors of 10–100 or greater. The enrichment process will allow analysis of these impurities in hydrogen using simpler and less expensive analytical instruments that can be deployed in the fields. A series of experiments was conducted with the device using a hydrogen analyte gas containing N2, CH4, and CO2 at ∼0.1% each, CO at ∼100 ppm, and H2S at ∼2 ppm. Chemical analyses of the impurity-enriched sample showed that for the non-sulfur species, the measured enrichment factors were 14.5–14.9, which closely matched the calculated enrichment factors of 14.8–14.9. The elemental material balances indicated a good accounting of the non-sulfur impurity species. For the sulfur species, some initial sulfur loss was observed, presumably due to interaction with the surfaces and/or analytical deficiencies. The impurity enrichment factors for such sampling devices are functions of the sampler size, and the sample vessel pressures before and after enrichment. Depending on the volume of the enriched sample needed for analysis, the device can be designed to enrich the impurities in hydrogen by more than a factor of two orders of magnitude for practical and economical field applications.
The role of dissolved oxygen in supercritical water in the oxidation of ferritic–martensitic steel
Abstract To assess the role of dissolved oxygen in supercritical water on the growth processes of oxide scales, a marker experiment of ferritic–martensitic steel was performed by exposing to supercritical water (H 2 16 O) containing marked 18 O 2 at 600 °C under 25 MPa. The oxide scale was analysed by using Secondary Ion Mass Spectrometry (SIMS). The oxygen isotope profile shows that dissolved oxygen and supercritical water react with metals simultaneously. Dissolved oxygen changes the oxidation/reduction potential of supercritical water leading to an increase in the oxidation rate. The oxidation rate increases with increase in dissolved oxygen content in supercritical water. The mechanism of the effect of dissolved oxygen on oxidation is discussed.