A New Technology for Hydrogen Safety: Glass Structures as a Storage System

1. A New Technology for Hydrogen Safety: Glass Structures as a Storage System Ronald Meyer BAM Federal Institute for Materials Research and Testing Division II.1 “Gases, Gas Plants” 12205 Berlin, Germany C.En Ltd., 3 Sonnhaldenstrasse Postfach CH-8032 Zurich, Switzerland

2. Contents • Idea • Safety aspects • Storage principles • Conclusion/Perspectives

3. picture of a round capillary array Idea 1 mm • Model of a capillary array, scale 250:1

4. Why Use Multi-Capillary Arrays?

5. Why Use Multi-Capillary Arrays? Multi-Capillary Arrays have a number of outstanding characteristics: • Mechanically strong • Crash safety • Environmentally friendly • Reusable • Low hydrogen diffusion • Chemically durable • Light weight

6. Contents • Idea • Safety aspects • Storage principles • Conclusion/Perspectives

7. Pressure Tests • Capillaries made of different glass materials have been tested • Sodium carbonate ● Quartz • Alumina silicate ● Borosilicate • Different gases for pressure tests • Maximum Burst Pressure: 132.4 MPa / 19203 psi for single capillaries 117.3 Mpa / 17013 psi for arrays

8. Pressure Tests • Parameters varied: • Inner diameters from 120 µm up to 3 mm • Wall thicknesses from 10 µm up to 290 µm • Different lengths from 100 mm up to 300 mm • Different diameter-wall thickness-ratios

9. Diameter-Wall thickness-Ratios

10. Statistical Evaluation • Burst pressure of single capillaries are important basic information • Information about the reliability of complex bundled systems • Failure probability statistics of capillaries

11. Weibull-Distribution • It is a statistical distribution which is used for determination of durability in quality management • Especially used at material fatigue of brittle materials • Different number of samples of the same design and construction have to be tested at defined conditions till a collapse eventuates

12. Statistical Evaluation Quartz Borosilicate

13. Statistical Evaluation Quartz Borosilicate

14. Permeation Released hydrogen during vacuum hot extraction • Measuring H2-concentration with mass spectroscopy • T < 600 °C release of surface absorbed H2 • T > 650°C release of enclosed permeated H2 out of closed capillary • permeation around 10-14 mol cm-1 s-1 atm-1 at 200°C Open capillary Closed capillary

15. Stress modeling Reference: Marek Gebauer Material stresses in single capillaries and capillary arrays with and without defects at 500 bar internal pressure, calculated with the COMSOL code using the von Mises plastic distortion hypothesis

16. Contents • Idea • Safety aspects • Storage principles • Conclusion/Perspectives

17. Stopper alloy Ø500µm Alloy for closure • Array filled with alloy, capillaries properly closed End of capillary array after completed filling and releasing procedure

18. Prototype No. 3 pre-volume storage part • Heating coil • Coil made of insulated electric wire • PTFE shell • Protection against mechanical damage (shown here as transparent) sampling point • Sealing system • Connects storage unit to application • Glass capillary arrays • Main storage device Ø 16 mm 130 mm • Electric contacts • Connects heating coil to external power supply

19. Storage Principles Stopper Alloy • Long time storage • Low-melting alloy as closing system for every single capillary • Cheap solution without high constructional afford • Heat energy for closing and for opening • Electronic control unit for heating needed • Special setup for filling necessary, no in-situ possible

20. Prototype with micro valve for closure

21. Storage Principles Valve • Short time storage • Alterning demand or quick providing • Short release-period with different flows and pressure ratios • In-situ filling is possible • No or low energy-supply necessary

22. Contents • Idea • Safety aspects • Storage principles • Conclusion/Perspectives

23. Conclusions/Perspectives • Capillaries are able to withstand high pressures • Glass capillaries systems demonstrate the possibility of lightweight storage systems in every shape and volume • In tests for single capillary gravimetric capacity of • 33 wt% and vol. capacity of 45 g/l • Usage over a wide range of applications, up- and down scaling for adaption possible • Long time as well as short time storage systems are realizable

24. Conclusions/Perspectives • System is split into several modules, in case of leakage or impact only the damaged module will release the amount of stored hydrogen • Possibility of hazardous situations much lower than of a single-tank-solution • Safety evaluation only for a complete system possible

25. Ende Thank you very much for your attention. If there are any questions left don`t hesitate to ask me.

26. Backup

27. Storage Procedure • Operating pressure: 150 MPa (21750 psi) • Arrays placed in high pressure vessel in vertical position • Stopper alloy is positioned on top of arrays • After reaching the storage pressure the whole system is heated up • The alloy is melting and is pressed in the arrays with a pressure application • After cool down and release of pressure the storage procedure is finished High pressure vessel Stopper alloy 3 – array prototype

28. Release procedure in heatable autoclave ~25% gravimetric storage capacity

29. Updated Hydrogen Storage Targets * U.S. Department of Energy- Hydrogen Program, March 2010