HyCoRA (Hydrogen Contaminant Risk Assessment)

Transcription

1 HyCoRA (Hydrogen Contaminant Risk Assessment) - project objectives, scope and brief summary of results Jari Ihonen VTT Technical Research Centre of Finland Ltd

2 Project summary for HyCoRA In FCH JU 2013 call a VTT-lead consortium submitted a project proposal to the topic SP1-JTI-FCH (Fuel quality assurance for hydrogen refuelling stations). The project started Research partners are:, VTT (coordinator &WP4 leader), CEA (WP1 leader), SINTEF (WP2&WP3 leader), JRC (WP5 leader) Industry partners are: Powercell Sweden AB supplier of automotive stacks Protea Ltd developer of new analytical instruments Since there are no automotive OEMs or hydrogen refuelling station producers/operators in the consortium, the advisory board is open for all companies in these categories. 2

3 Project structure (Pert diagram) In WP1-WP3 technical work is done. The uniting link between all the WPs and phases of work is the risk assessment work package (WP4). In WP4 synthesis of data is used for quantitative risk assessment, which determines the need for gas quality, QA requirement and additional hydrogen purification steps. OEM advisory board work is done within WP5 led by JRC. 3

4 HyCoRA Overall objective expected outcome Overall project objective / Scope of Work The overall objective is to reduce cost of hydrogen fuel quality assurance (QA) for (Hydrogen Refuelling Station) HRSs Expected Outcome Cheaper and more reliable fuel quality assurance procedures and instrumentation for HRSs 4

5 The cost of automotive grade hydrogen is too high For large scale commercialisation of FC vehicles hydrogen delivered to retail station should be under 5 / kg in the long term In most of the current HRS, expensive hydrogen is delivered from sources with very low risk in order to fulfil requirements of ISO standard In the commercialisation phase of FCEV low cost hydrogen sources should be utilised. 5

6 HyCoRA strategy Risk Assessment In HyCoRA project qualitative and quantitative risk assessment is applied to optimise the needs for the QA with existing (draft) ISO standard Risk assessment provides information for the required frequency and accuracy for the gas analysis at the nozzle and/or in production Risk assessment gives the right focus for development of the new analytical methodology for the gas analysis Risk assessment requires information from: a) the real susceptibility for various poisonous species specifically for automotive applications automotive type FC system data needed b) probabilities for QA failure in hydrogen production site and/or at HRS data for gas analysis methods needed c) concentration correlations between contaminant species in fuel - impurity concentrations at production sites and HRS nozzle needed 6

7 WP1 Determination of susceptibility of hydrogen contaminants for automotive applications Review of state-of-the art knowledge and identification of knowledge gaps - is done The consequences of exceeding ISO impurity limits of PEMFCs for various poisonous species under actual automotive drive cycles are studied using automotive type stacks and MEAs - is partially done for formic acid, formaldehyde The large part of the work is done at PEFC system level using miniature automotive systems with hydrogen recirculation and measurement of recirculating gas composition (CO, CO 2, N 2 ). Done with good results. The start and stop times effect as well as the effect of different drive cycles are studied. Done with good results. The change of gases in the stack during the start and stop is analysed. How? Desorption of irreversible contaminants (like S) is studied during start and stop 7

8 WP1 Miniature automotive systems for the determination of susceptibility of H2 contaminants for automotive applications Documented in: Keränen, T.M., Karimäki, H., Viitakangas, J., Vallet, J., Ihonen, J., Hyötylä, P., Uusalo, H., Tingelöf, T. Development of integrated fuel cell hybrid power source for electric forklift (2011) Journal of Power Sources, 196 (21), pp Karimäki, H., Pérez, L.C., Nikiforow, K., Keränen, T.M., Viitakangas, J., Ihonen, J. The use of on-line hydrogen sensor for studying inert gas effects and nitrogen crossover in PEMFC system (2011) International Journal of Hydrogen Energy, 36 (16), pp K. Nikiforow, H. Karimäki, T.M. Keränen, J. Ihonen, Optimization study of purge cycle in PEMFC system, (2013) Journal of Power Sources, 238, pp

9 System test bench (1-2 kw) The test bench consists of three main subsystems: anode, cathode and coolant Additional instrumentation includes contaminant injection line and gas sampling loop Anode is operated in dead end (constant fuel feed pressure) with purge 9

10 Single cell vs. system test bench measurements - how to obtain usable results with single cell???? 10

11 Schematic of the anode recirculation system developed at VTT (and JRC, LANL) 11

12 Single cell anode gas recirculation system features Anode humidification by recirculation ( ml/min) Anode humidification level controlled by anode exit pipe temperature and recirculation rate Humidification by recirculation eliminates contaminants (O 2, CO 2, other contaminants) from the humidifier water Oxygen contamination invalidates easily sub-ppm CO contamination measurements Fuel utilisation up to about 99.5% is possible (as in FCEV) Active back pressure control is problematic (PID problem) Recirculation rate is measured using humidity sensors (Vaisala HMT317). Exit gas at anode (and cathode, if needed) is analysed by GC (CO, CO2, CH4) and by hydrogen concentration sensor. This design is always a compromise between number of options. Overcomplicated system should be avoided. 12

13 Result example: CO level of fuel at the cell exit is different, when cells vs. stacks or open anode vs. recirculation is used Anode gas CO and CO2 concentration in single pass (open anode) mode. 1 ppm CO and 0.6 Acm -2. Poisoning with 5 ppm CO and 0.6 Acm

14 Contaminant sources from various production methods (SAE J2719/1) Terlip, D., et al. H2FIRST Hydrogen Contaminant Detector Task: Requirements Document and Market Survey. NREL/TP , April p. 14

15 Impact of formic acid single cell measurement ppm HCOOH -> 5-10 mv very slow effect 15

16 Impact of formic acid stack measurement ppm HCOOH -> 5 mv very slow effect - HCOOH effect on CO poisoning time is almost negligible Almost negligible effect because only few mv degradatio. The same effect in stack and single cell. 16

17 Impact of formaldehyde stack measurement ppm HCHO -> 20 mv very slow effect - cell voltage distribution (not observed with formic acid) behaviour more similar to CO than formic acid - poisoning effect less than 50% compared to 1 ppm CO in similar conditions 17

18 Some conclusions from WP1 for the risk model CO surface coverage of about % level is causing 50 mv voltage drop at medium/high power ( Acm-2) Non-optimised GDL (flooding) may multiply the CO effect The results of CO poisoning measurements are dependent on cell/stack design and operation (open anode / recirculation) Formic acid and formaldehyde has very weak poisoning effects. The limits in ISO :2012 seem to be times too low. CO is cleaned during SU/SD during few hours results shown in another presentation. 18

19 Work proposals for the last 18 months in HyCoRA Measurements with H2S to study the desorption of sulphur from the catalyst (how reversible is S adsorpion?) Measured by changes in CO tolerance Must be done with recirculation system (Matsuda, et al., 2009) Modelling and measurements of SU/SD effects with stacks in the miniature automotive systems Gas exchange dynamic is most probably system dependent. Measurements with formaldehyde and formic acid are continued to provide convincing evidence for the revision of ISO Measurement of CO oxidation by internal air bleed during operation Requires extremely pure gases and good gas quality 19

20 WP2: Development and characterisation of analytical methods for H2 quality assurance Key challenges Development of novel traceable methods and standards New traceable methods for components in ISO Use of static and dynamic standards of unstable compounds Interlaboratory comparison for hydrogen purity Exploratory research to develop a robust and traceable metrological approach for the analysis of total halogenated compounds Validation of online analysers for hydrogen purity measurement Assessment of the LoD and uncertainty of instruments currently in use for the online analysis of hydrogen Investigation of online analysis for measuring more challenging compounds Testing and validation of new analysers for measuring multiple impurities Tests to validate the performance (measurement uncertainties, LoD, analysis time, sensitivity to cross-interferences, etc.) of a multi-component analyser Use of traceable gas standards and analysis methods at NMIs to assess the performance of the instrument against existing methods of analysis 20

21 LP FTIR Excellent sensitivity No application to homonuclear species LOQ CO 5 ppbv Applied to CO, CO 2, H 2 O, SO 2, THC, HF, HCl Online application later in project 21

22 WP3: Assessment of hydrogen quality variation in hydrogen refuelling stations Fuel composition and variations in impurity concentrations at HRS fuel nozzle are determined by extensive on-site measurements. This information, especially correlations between gas impurity concentrations, is used in risk assessment for the identification of suitable canary species and acceptable limits for them. Hydrogen quality variation in production sites is determined by on-site measurements, literature data and modelling. Hydrogen quality variation for different production (biogas, reforming, electrolysis, by-product etc.) and purification (PSA, H2 liquefaction) options now and in the future are quantified by process analysis and modelling. Failure in purification (PSA, H2 liquefaction, etc.) options now and in the future are quantified with help of WP4 experts. 22

23 Gas sampling unit (Linde) Linde 'Qualitizer' No IrDA: maximum 600 bar sampling in.de Manual override of HRS safety not required 23

24 Sulphur distribution max 10% of ISO limit. Highest level from S-free sources!* Water Electrolysis Steam Methane Reforming Chlor-Alkaline Total sulphur (ppmv) US: same species HY-1 HY-2 HY-3 HY-4 HY-5 HY-6 HY-7 HY-8 ID HY-1 HY-2 HY-3 HY-4 HY-5 HY-6 HY-7 HY-8 TS ppmv H 2 S frac COS frac CS 2 frac *The source of sulphur can be e.g. stainless steel tubing, see p. 5 in: 24

25 WP4: Risk assessment of hydrogen quality assurance failure WP4 receives data for initial assessment from WP1/WP2 for FC measurements and development efforts of hydrogen impurity analysis After initial assessment WP4 have received data from WP1/WP2/WP3 for mid-term evaluation and further directing of WP1/WP2 SU/SD experiment and results has been important, as now it can be assumed that the Pt surface is CO-free after every overnight stop -> short (max 8 h) experiments are sufficient WP4 summarises the efforts of WP1/WP2/WP3 and provides final risk assessment for the WP5 for recommendations Risk assessment WP educates all project partners so that risk assessment based thinking is part of everyone s work 25

26 Background in the chosen NG-SR-PSA chain the most relevant component is CO Tentative influence diagram model for the impact of CO contamination in HRS dispenced fuel on FCEV population 26

27 The risk model looks CO coverage during one day Tentative ID model for CO contamination impact on FC stack 27

28 Overnight cleaning of the Pt surface is the key part of the CO contamination mitigation 28

29 Simulation results based on CO model version 1.0 Forecasted conditional probability of experiencing an incident in daily operation (given the stack age and fuel CO level) Pr(Incident) = IncidentCount / No of simulations Averaged from 3 simulation runs per setting (no seed used) 29

30 WP5: Dissemination, recommendations and communications Recommendations for QA protocols, QA instrumentation are done based on the risk analysis from WP4 Possibility of revising levels of impurities for ISO standard are discussed with automotive advisory board and communicated to ISO TC 197/WG 12 and SAE This work package arranges also seminars and workshops for communicating the results between project and public. In this work package the main part of the communication with automotive advisory board (OEM communication) is arranged and communication is passed to other WPs via WP4 30

31 Summary HyCoRA project is a very open project and all OEMs are still welcome to join the advisory board. HyCoRA work is done in international co-operation, mainly with USA (LANL, ANL) HyCoRA project uses risk assessment to focus the research in right way. In HyCoRA project a large part of fuel cell contamination work is done using down-scaled automotive type PEMFC systems and automotive type stacks. Gas analysis methods are developed to reduce the cost of QA. 31