Welcome to the HyFacts Short Course

1. Welcome tothe HyFacts Short Course • Chapter FC: • Safety of applications, including coverage by standards: stationary fuel cells and indoor systems • Compiled by Christian Machens, TÜV SÜD Akademie

2. Stationary fuel cells Fuel cells generate water from a fuel (such as hydrogen or natural gas) and from oxygen in the air, while producing electricity and heat. This reaction is carried out in each of the basic cells of the fuel cell. Each fuel cell consists of an anode, a cathode, and an electrolyte allowing the charges to move from one side to the other side of the fuel cell. As described in Figure 146, electrons move from the anode to the cathode through an external circuit, producing an electrical current - and thus powering the load. Such cells are placed in series, to reach an adequate voltage output. When assembled together, the cells constitute an energy module of the required power known as the stack. Figure 147: Example of a stationary fuel cell: the Comm PacTM system, developed by Axane Figure 146: Block diagram of a fuel cell

3. Stationary fuel cells • Different types of fuel cells exist. The main types of fuel cells are: • Proton Exchange Membrane Fuel Cells (PEMFC), • Alkaline Fuel Cell (AFC), • Solid Oxide Fuel Cells (SOFC) and • Molten Carbonate Fuel Cells (MCFC). • These fuel cells are classified according to the type of electrolyte they use. • In Proton Exchange Membrane Fuel Cells, a proton-conducting membrane is used as an electrolyte. In pure hydrogen PEMFC, hydrogen is dissociated into protons H+ and electrons on the anode. Protons are conducted through the proton-conducting membrane to the cathode. As the membrane is electrically insulated, electrons move from the anode to the cathode through an external circuit, producing an electrical current. On the cathode, oxygen reacts with the electrons and protons to form water. Such fuel cells operate at temperatures between 50 and 220°C, typically 80°C.Other types of PEMFC also exist: some are fed with a mixture of CO2 and H2. • Proton Exchange Membrane Fuel Cells are preferred for mobile applications.

4. Stationary fuel cells • Alkaline Fuel Cells (AFC) are low-temperature fuel cells (65°C) with a high efficiency. Though the technology as such is proven, little activities are dedicated to this technology. The electrolyte is liquid Potassium hydroxide (KOH) which offers good possibilities for cooling the cells. • In Solid Oxide Fuel Cells, a ceramic material called yttria-stabilized zirconia (YSZ) is most commonly used as an electrolyte. In SOFC, oxygen gas reacts on the cathode with electrons, to form negatively charged oxygen ions. These oxygen ions move through the electrolyte from the cathode to the anode, where they react with hydrogen gas, producing electricity and water. SOFC operates at high temperatures (between 800 and 1000°C). They can be fed with fuels other than hydrogen gas, such as natural gas for instance. Natural gas is then reformed (i.e. converted to hydrogen) internally. • In Molten Carbonate Fuel Cells, lithium potassium carbonate salt is used as an electrolyte. At high temperatures (about 650°C), this salt melts and allows for the movement of the negative carbonate ions from the electrolyte. On the anode, hydrogen reacts with carbonate ions to produce mainly water, carbon dioxide and electrons. The electrons move from the anode to the cathode, producing an electrical current. On the cathode, carbon dioxide (from the anode) and oxygen react with the electrons to form carbonate ions. MCFC can be fed with fuels other than hydrogen gas, such as natural gas for instance • Because of their high operating temperatures, Molten Carbonate Fuel Cells and Solid Oxide Fuel Cells have slow start-up times. Therefore, they are not suitable for mobile applications and are limited to stationary applications.

5. Hazards and safety measures Fuel cells are low-pressure systems: upstream the fuel cell, the hydrogen feed pressure is reduced down to low pressures (e.g. 250 mbar at the cells’ inlet of Axane’s fuel cell Comm PacTM). Therefore, stationary fuel cell systems are free from hazards related with the handling of pressurized hydrogen. But, since fuel cells consist of a stack of basic cells in which chemical reactions involving hydrogen are carried out, there is a risk of leaks. In order to avoid the formation of flammable mixtures, sensors able to detect hydrogen leaks are used. Once sensors have detected the presence of hydrogen at a concentration higher than a threshold value, isolation measures are taken.

6. Stationaryapplications: standards IEC/TS 62282-1:2010 Fuel cell technologies Part 1 Terminology, Edition 2 IEC 62282-2:2007Fuel cell technologies Part 2: Fuel cell modules, Edition 1.1 Provides the minimum requirements for safety and performance of fuel cell modules. Applies to fuel cell modules with the following electrolyte chemistry: alkaline; proton exchange membrane (including direct methanol fuel cells); phosphoric acid; molten carbonate; solid oxide fuel cell modules.

7. Stationaryapplications: standards IEC 62282-3-100Fuel cell technologies Part 3-100: Stationary fuel cell power systems – Safety Edition 1 (Revision of IEC 62282-3-1) Appliestostationarypackaged, self-containedfuelcell power systemsorfuelcell power systemscomprisedoffactorymatchedpackagesofintegratedsystemswhichgenerateelectricitythroughelectrochemicalreactions. Is a productsafetystandardsuitableforconformityassessment. IEC 62282-4 Fuel cell technologies – Part 4-100: Fuel cell systems for forklift applications Safety requirements, environmental aspects and test procedures, Edition 1 will cover safety, performance, construction, marking and test requirements and interchangeability of fuel cell systems onboard specialty vehicles other than road vehicles and auxiliary power units (APUs). However, the first edition of this document will include items applicable to forklifts. The future editions of this document will include items applicable to onboard vehicles other than road vehicles and APUs Ad hoc group no.2 Safety aspects with respect to explosion

8. Stationaryapplications: standards IEC 62282-3-150Fuel cell technologies Part 3-150: Stationary fuel cell power systems - Small stationary fuel cell power system serving as a heating appliance providing both electrical power and useful heat with or without a peak load heating device. This standard applies to fuel cell power systems that are intended to be permanently connected to the electrical system of the customer (end user). Connection to the mains directly (parallel operation) is also within the scope of this standard IEC 62282-3-3Fuel cell technologies Part 3-3: Stationary fuel cell power systems – Installation, Edition 2 Providesminimumsafetyrequirementsfortheinstallationofindoorandoutdoorstationary fuelcell power systems in compliancewith IEC 62282-3-1; appliestotheinstallationof systemsintendedforelectricalconnectiontomainsdirectlyorwith a transferswitch, or intendedfor a stand-alone power distributionsystem, orintendedtoprovide AC or DC power.

9. Stationaryapplications: standards IEC 62282-4 will cover safety, performance, construction, marking and test requirements and interchangeability of fuel cell systems onboard specialty vehicles other than road vehicles and auxiliary power units (APUs). However, the first edition of this document will include items applicable to forklifts. The future editions of this document will include items applicable to onboard vehicles other than road vehicles and APUs Ad hoc group no.2 Safety aspects with respect to explosion IEC 62282-3-1:2007Fuel cell technologies Part 3-1: Stationary fuel cell power systems – Safety Edition 1

10. Indoor installation of hydrogen systems Passive ventilation Enclosures with two openings allow for better natural ventilation than enclosures with only one opening (see section 3.2.6.3). The openings should preferably be located on two different walls diametrically opposed of the enclosure (one opening is at the bottom of a wall and one outlet opening is at the top of the opposed wall enclosure), so that a displacement ventilation can take place (see section 2.5.3.3). Attention must be given to the direction of the wind as an opposing wind might limit the effects of natural ventilation Figure 148: Small opposing wind Triggered and permanent forced ventilations For triggered ventilation, an ATEX certified mechanical ventilation system should be used, For permanent forced ventilation, a non-ATEX certified mechanical ventilation system can be used. But this non-ATEX certified mechanical ventilation system should be shut-off and replaced by an ATEX certified mechanical ventilation system as soon as the hydrogen threshold concentration has been reached. The mechanical ventilation system should preferably be installed in a high location.

11. Indooruseof hydrogen: standards • Partially covered by ISO 62282-3-3 (Fuel Cell Technologies: Installation) • ISO/TR 15916:2004 (Basic considerations for the safety of hydrogen systems) • provides guidelines for the use of hydrogen in its gaseous and liquid forms. It identifies the • basic safety concerns and risks, and describes the properties of hydrogen that are relevant • to safety. Detailed safety requirements associated with specific hydrogen applications are • treated in separate International Standards. • ISO 26142 (for hydrogen detectors)

12. Indooruseof hydrogen: standards • IEC 60079-1, Explosive atmospheres • Part 1: Equipment protection by flameproof enclosures “d” • Part 2: Equipment protection by pressurized enclosures “p” • Part 7: Equipment protection by increased safety “e” • Part 11: Equipment protection by intrinsic safety “i” • Part 15: Equipment protection by type of protection “n” • Part 18: Equipment protection by encapsulation “m” • IEC/TR 60079-20-1, Explosive atmospheres • Part 20-1: Material characteristics for gas and vapour classification — Test methods and data • IEC 60079-29-1, Explosive atmospheres • Part 29-1: Gas detectors — Performance requirements of detectors for flammable gases