Overview of Hydrogen Fuel Cells 230

acoustic imaging

An inspection method that uses ultrasound to produce images of soundwaves. Acoustic imaging can be used to identify the location of a hydrogen fuel leak by identifying where the sound of the leak comes from.

ambient temperature

The temperature of the air that surrounds devices and systems. Hydrogen can be stored at an ambient temperature if other conditions, especially pressure, are met.

anode

The negative electrode in a fuel cell. The anode of a hydrogen fuel cell is often made of platinum.

asphyxiation

The obstruction of breathing due to an inadequate supply of oxygen. Asphyxiation can lead to death.

atoms

A particle that makes up elements. An atom is the smallest distinguishable unit of an element that retains the element’s characteristics.

bar

A unit of pressure used in the metric system. One bar is equal to 14.5 pounds per square inch.

battery

A device that converts chemical energy into electrical energy. Batteries consist of multiple individual cells and are used to power electric vehicles.

brittle

Unwilling to be drawn, stretched, or formed. Brittle metals tend to break if subjected to these forces.

carbon fiber

A material made from slender, thread-like strands of carbon, a strong, non-metallic element. Carbon fiber is a commonly used composite reinforcement material.

carbon monoxide

CO. A colorless, odorless, poisonous gas made of carbon and oxygen. Carbon monoxide may be released during processes that produce hydrogen fuel, including natural gas reforming.

catalyst layer

A platinum layer of the proton exchange membrane (PEM) in a fuel cell. The catalyst layer breaks down hydrogen into protons and electrons and directs their flow through the electrolyte.

cathode

The positive electrode in a fuel cell. The cathode of a hydrogen fuel cell is often made of platinum.

check valve

A directional control valve that blocks flow in one direction and allows flow in the opposite direction. Check valves prevent hydrogen fuel from flowing backwards out of the storage tank.

circuit

A completely enclosed path for electrical current. Electrical circuits include a source, path, load, and control.

composite

A material composed of two or more unlike materials that are bonded together without losing their individual properties or characteristics. The materials in composites are generally layered or suspended within one another.

concentrations

The amount of a substance contained within a given amount of space. When the concentration of hydrogen is 4-75% in a given space, and the concentration of oxygen is18-59%, hydrogen can combust or explode.

contaminants

Any foreign substance that causes a loss of efficiency or a breakdown in a fluid system. If a contaminant enters a hydrogen storage tank, it can lead to unwanted chemical reactions, such as explosions.

control unit

A component in hydrogen fuel cell electric vehicles (FCEVs) that monitors for faults or errors. The control unit can shut a vehicle down if it identifies unsafe conditions, such as issues with fuel lines or the electrical system.

cryogenically

A means of storing liquid hydrogen using extremely cold temperatures. Cryogenically stored hydrogen requires temperatures of –423°F (–252°C).

cylindrical

Having a three-dimensional (3D) shape with a circular base and top connected by parallel walls. Cylindrical tanks are ideal for storing hydrogen fuel because they can more evenly distribute pressure.

density

The amount of mass within a specific volume. Objects with greater density have increased mass and weight.

displace

To change the overall position of a substance or object. Hydrogen’s ability to displace oxygen quickly can lead to asphyxiation.

electric shock

The flow of electricity through the body. Severe electric shock can be fatal.

electric vehicles

EVs. An automobile or other type of vehicle powered by an electrical system. Electric vehicles require batteries or fuel cells to produce electricity.

electricity

A form of energy created by the movement of electrons. Electricity is produced in electric vehicles using either a battery or a fuel cell.

electrodes

A conductor that controls the flow of electricity. There are two electrodes in fuel cells and batteries, the anode and the cathode.

electrolysis

A process that passes an electric current through a substance to create a chemical change. Electrolysis is used to produce hydrogen fuel without creating carbon emissions.

electrolyte

A conductive solution containing an acid, an alkaline, or a salt. The electrolyte in a fuel cell or battery separates the two electrodes.

electron

A negatively charged particle that orbits the nucleus of an atom. The flow of electrons causes the flow of electricity.

energy

The ability to do work. Energy comes in many forms, including electrical, mechanical, thermal, and chemical energy.

energy diversity

The diversification of energy resources within a country, such as using wind, solar, and hydrogen power to create energy. Energy diversity increases energy independence within a country.

energy independence

A state in which a country does not need to import energy resources to meet its energy needs. Energy independence can be achieved by using renewable energy resources, improving energy efficiency in infrastructure, increasing energy storage capabilities, and updating the electrical grid.

energy storage systems

A device or group of devices capable of storing energy in order to supply electrical energy at a later time. Energy storage systems receive energy through many means, such as solar power, hydropower, and batteries.

EVs

Electric vehicles. An automobile or other type of vehicle powered by an electrical system. EVs require batteries or fuel cells to produce electricity.

FCEVs

Fuel cell electric vehicles. A type of electric vehicle that uses an electric motor powered by fuel cells to move and operate the vehicle. FCEVs that use pure hydrogen as a fuel source produce only water as emissions.

flammable

Capable of easily and quickly catching fire. Flammable substances ignite at low temperatures.

fuel cell

A device that uses gas to convert chemical energy into electrical energy. Fuel cells are potentially very efficient power sources.

fuel cell electric vehicles

FCEVs. A type of electric vehicle that uses an electric motor powered by fuel cells to move and operate the vehicle. Fuel cell electric vehicles that use pure hydrogen as a fuel source produce only water as emissions.

fuel cell stack

A collection of individual fuel cells. In a fuel cell stack, each individual fuel cell contains an anode, a cathode, and an electrolyte that produce electrical energy.

gas

An airlike fluid that expands freely to fill any space available, regardless of its quantity. Gas differs from liquid in that there are no forces keeping gas molecules together.

gas diffusion layer

A carbon fiber layer of the proton exchange membrane (PEM) in a fuel cell. The gas diffusion layer ensures that hydrogen is evenly distributed throughout a fuel cell.

gasket layer

A polymer layer of the proton exchange membrane (PEM) in a fuel cell. The gasket layer holds elements of the electrolyte together and prevents leaks from occurring.

grounded

Safely connected to a neutral body that can absorb stray electrical currents. Grounded motors and circuits reduce the risk of injury and damage.

hydrogen

H. A colorless, odorless gas that is the most abundant element on the planet. Hydrogen is abundant but highly combustible and requires lots of energy into be converted to fuel.

hydrogen fuel cells

A type of fuel cell that consumes hydrogen as energy. Hydrogen fuel cells do not produce carbon emissions.

impact-resistant

Capable of withstanding sudden shock or impact without deforming or breaking. Impact-resistant tanks are less likely to leak and can help reduce the risk of combustion or explosion.

insulation

A material that does not conduct electricity and is used to cover electrical conductors. Insulation contains current to prevent excess leakage and other faults.

International Organization for Standardization

ISO. A non-governmental organization that develops and establishes standards, rules, and guidelines designed to ensure that products, processes, and services are fit for their purposes. The International Organization for Standardization produces standards related to the production of hydrogen fuel cell electric vehicles (FCEVs).

ISO 16111

A standard developed by the International Organization for Standardization (ISO) related to hydrogen fuel cell electric vehicle (FCEV) manufacturing. ISO 16111 outlines the requirements for fuel storage, including tank design and construction.

ISO 17268

A standard developed by the International Organization for Standardization (ISO) related to hydrogen fuel cell electric vehicle (FCEV) manufacturing and safety. ISO 17268 outlines the requirements for storage tank design and construction, performance requirements, and safety considerations.

leak detectors

A sensor that identifies hydrogen leaks in a hydrogen fuel cell electric vehicle (FCEV). Leak detectors are located throughout a hydrogen FCEV, including near the fuel tank, the fuel cell stack, and the fuel lines.

Li-ion batteries

Lithium-ion batteries. A secondary cell that uses a lithium compound as the cathode. Li-ion batteries typically use graphite as the anode and a lithium salt as the electrolyte.

liquid

A state of matter that is cohesive and has the ability to flow. Liquids are the room temperature forms of some substances, such as water, and the melted forms of others, such as metals.

lithium-ion battery

Li-ion battery. A secondary cell that uses a lithium compound as the cathode. Lithium-ion batteries typically use graphite as the anode and a lithium salt as the electrolyte.

membrane electrode assembly

MEA. The main components of a hydrogen fuel cell. The membrane electrode assembly is composed of the anode, cathode, and proton exchange membrane.

metal alloys

A material created by intentionally mixing two or more other materials, one of which must be metal. Metal alloys often have the desirable mechanical and physical properties of both materials.

National Fire Protection Association

NFPA. A non-profit organization devoted to eliminating deaths, injuries, and damage caused by fires. The National Fire Protection Association publishes standards for fire safety and firefighting equipment.

national security

The security and defense of a country, including its citizens, economy, and institutions. National security increases when a country limits its dependence on international trade.

natural gas reforming

A process used to produce hydrogen as a fuel source. Natural gas reforming combines natural gas with steam and heat, which breaks it down into usable hydrogen fuel and carbon waste.

NFPA 2®

A standard developed by the National Fire Protection Association (NFPA) related to safety surrounding the production and use of hydrogen fuel cell electric vehicles (FCEVs) and firefighting protocols. NFPA 2® outlines safety guidelines for fuel storage, fuel cell design and storage, and emergency response.

NFPA 505

A standard developed by the National Fire Protection Association (NFPA) related to safety surrounding the production and use of hydrogen fuel cell electric vehicles (FCEVs). NFPA 505 outlines safety guidelines for vehicle design, fuel storage, and emergency equipment.

oxygen

O. A colorless, odorless gas present in the air. Oxygen is present in a fuel cell’s cathode, but it is flammable when mixed with hydrogen in certain quantities.

PEM

Proton exchange membrane. The layer of the electrolyte that allows hydrogen protons to pass from the anode to the cathode. The PEM, also called the polymer electrode membrane, prevents other gases from passing through.

platinum

Pt. A precious, grayish-white, metallic element that is paramagnetic. Platinum is used in the production of anodes and cathodes for fuel cells.

polymer

A material made of long chains of molecules. Polymers include plastic, rubber, and other natural or synthetic materials.

positive hydrogen ions

H+ ions. A positively charged particle within a hydrogen atom. Positive hydrogen ions are protons that are located in the nucleus of a hydrogen atom.

pounds per square inch

psi. A unit of pressure used in the English system. Pounds per square inch measures the amount of pressure that is applied over an area of one square inch.

pressure

The exertion of a mechanical force upon a substance or object. High levels of pressure are required to store hydrogen compactly enough for it to be used as an efficient fuel source in hydrogen fuel cell electric vehicles (FCEVs).

proton exchange membrane

PEM. The layer of the electrolyte that allows hydrogen protons to pass from the anode to the cathode. The proton exchange membrane, also called the polymer electrode membrane, prevents other gases from passing through.

protons

A positively charged particle within an atom. Protons are positive ions located in the nucleus of an atom.

range

The distance a vehicle can travel on a full tank of fuel or a full battery charge. The range of a hydrogen fuel cell electric vehicle is comparable to that of a vehicle that uses a lithium-ion battery.

regenerative braking

A capability used in electric vehicles that collects and stores energy from braking to supplement power to the electric motor. Regenerative braking is equipped in both fully electric and hybrid electric vehicle types.

SAE J2579

A standard developed by the Society of Automotive Engineers (SAE) related to safety surrounding the production and use of hydrogen fuel cell electric vehicles (FCEVs). SAE J2579 outlines safety guidelines for fuel storage, fuel cell systems, safety devices, and emergency response.

sensors

A device that detects a change in a physical stimulus and turns it into a signal that can be measured or recorded. Sensors in a fuel tank can detect changes in pressure and/or temperature that can indicate a fuel leak.

shut-off valve

A valve that controls the on-and-off supply of fuel. The shut-off valve in a hydrogen fuel cell electric vehicle (FCEV) automatically defaults to the off position to prevent the accidental release of hydrogen.

Society of Automotive Engineers

SAE. An organization of engineers that sets most industry standards for the testing, measuring, and designing of automobiles and their components. The Society of Automotive Engineers publishes standards related to the automotive and aerospace industries.

standards

An established policy regarding a particular practice or method. Standards for hydrogen fuel cell electric vehicles (FCEVs) cover requirements for processes such as vehicle design, fuel cell construction, and storage safety.

steam

A gaseous state of a liquid that forms when the liquid boils. Steam is formed at high temperatures, usually at or above a liquid’s boiling point.

tailpipe emissions

The product of fuel combustion in vehicles. Tailpipe emissions are often but not always pollutants, such as carbon monoxide and carbon dioxide.

thermal imaging cameras

An inspection tool that creates an image of an object using infrared energy emitted by that object. Thermal imaging cameras can be used to view pure hydrogen fires, which are nearly invisible to the eye.

thermal pressure relief valve

An adjustable control valve that regulates pressure in a hydrogen fuel cell tank. The thermal pressure relief valve releases pressure when it is detected to exceed the expected amount inside a tank.

Type IV tanks

The grade of storage tank required to store usable hydrogen in a hydrogen fuel cell electric vehicle (FCEV). Type IV tanks can store contents at up to 10,000 pounds per square inch, or 689 bar.

vapor

A gaseous state of a liquid that forms when the liquid evaporates. Vapor is formed at many different temperatures, usually below a liquid’s boiling point.

voltage

The electrical force or pressure that causes current to flow in a circuit. Voltage is measured in volts (V).