The Hydrogen Economy

Written by Madeline Gozzi

Why has hydrogen become one of the most researched and potentially successful fuels of the future?  Climate science shows that we must limit global temperature increases to 1.5⁰ C above pre-industrial temperatures.[i]  At this point, the temperature on Earth is 1.1⁰ C higher than it was in the late 1800's.  At this pace, we must reduce carbon emissions by 45% by 2030 and reach Net-Zero emissions by 2050 to keep the planet from warming more than 1.5⁰ C.[ii]  The use of hydrogen as a fuel has the potential to help us reach the goal of Net Zero carbon emissions.

What does Net-Zero mean?  Net-Zero means reducing greenhouse gas (GHG) emissions to as close to zero as possible.  Almost everything we consume, produce, and transport currently creates GHGs.  The US, China, and Europe are among over 70 countries moving towards a net zero target, covering about 76 % of global emissions.  Over 3000 businesses and financial institutions are working towards a net zero target.

What is Green Hydrogen?

Hydrogen has been given different color designations depending on the energy source used to generate it. Green Hydrogen is produced using only surplus energy from renewable sources such as solar or wind power.  Renewable energy sources cannot always yield energy 24 hours a day, but excess energy is often produced during peak cycles.  Scientists are creating better ways to store the surplus energy that is made and use this energy to produce green hydrogen.  The percentage of hydrogen currently produced designated as green hydrogen is still less than 0.1%, however global green hydrogen production grew by about 44% from 2021 to 2022.[iii]

Black and brown hydrogen are made from two forms of coal: black (bituminous) or brown (lignite).  Hydrogen production from these coals creates the most GHG because there is no carbon capture for the released carbon dioxide or carbon monoxide.  Grey hydrogen uses natural gas or methane for its production.  The process used is called steam reforming.  Blue hydrogen is made using carbon generated in the steam reforming process that was captured and stored underground.  Because the carbon emissions are captured with blue hydrogen, it is referred to as carbon neutral, i.e., the carbon is not released into the air. 

How is Hydrogen Used and Stored?

The uses for hydrogen are numerous!  Hydrogen was used as the rocket propulsion fuel for the fuel cells on the US moon mission, putting the first people on the moon, and is used today in space exploration.[iv]  Hydrogen is being developed as a replacement or supplement for fossil fuels by several power plants.  Hydrogen is primarily used by heavy industries in the United States, such as petroleum refining, chemical and fertilizer production, and food processing.[v]^,[vi]  Effective ways of storing hydrogen are also expanding.[vii]^{, [viii]} Storing hydrogen using methods with a high energy density is one of the keys to expanding its uses.  Hydrogen can be stored underground in large quantities as the gas.[ix]  Liquid hydrogen storage is also possible but is very energy-intensive and expensive. 

Green Hydrogen: Poised for Growth

Major oil companies, like Chevron and Exxon Mobile, are investing heavily in developing clean energy options.  In September 2023, Chevron New Energies Division acquired a significant stake in Advanced Clean Energy Storage (ACES) project in Delta, Utah.  "The Advanced Clean Energy Storage project plans to use electrolysis to convert renewable energy into hydrogen and utilize solution-mined salt caverns for seasonal, dispatchable energy storage.”[x]  ACES Delta is developing a hub for renewable energy that will be able to produce, store, and bring green hydrogen to the western US.  ACES has developed solutions for renewable energy's short-term and long-term storage.  Very recently, the US government announced that it is prepared to allocate $7 billion to develop seven regional hydrogen hubs nationwide.  These hubs will create a network of clean hydrogen producers with infrastructure for storage, delivery, and use of clean hydrogen.

Hydrogen fuel cells use hydrogen to produce electricity and generate only water and a small amount of heat as the end products.  Hydrogen fuel cells power small electronic devices, small and large vehicles, and industrial processes. There are fuel cell power generators in the US with varying megawatt (MW) capacities.  In transportation, hydrogen fuel cell vehicles are much more available in Europe and Asia than in the US.  In early 2023, there were 254 Hydrogen Refueling Stations (HRS) in the EU, about 300 in China, and 60 in the US, with 59 HRS in California and 1 in Hawaii.  The HRSs look much like our familiar gas stations, where customers drive to the hydrogen pumps and refill the hydrogen tanks in their Fuel Cell Electric Vehicles (FCEV).[xi]  Refueling a FCEV takes about 5 minutes and FCEVs can travel a range of about 300 miles before needing to refuel. 

Generating Hydrogen

Hydrogen can be generated by water electrolysis with Proton Exchange Membrane (PEM) electrolysis being one of the most promising technologies for hydrogen production.[xii] A PEM electrolysis cell takes water and splits it into hydrogen and oxygen.  The hydrogen produced is categorized as green if the energy used to power the electrolysis cell, also known as an electrolyzer, is from renewable sources.  The PEM electrolysis cell is a solid polymer membrane coated with electrodes.  The electrodes use platinum (Pt) and iridium (Ir) as the reaction catalysts.  The water is oxidized into oxygen (O₂) and hydrogen ions (H⁺) at the Ir electrode, the anode.  The oxygen evolution reaction (OER) is catalyzed by Ir black.  The H⁺ travels across the cell to the Pt electrode, the cathode, where the H⁺ is reduced to hydrogen gas (H₂).  The hydrogen evolution reaction (HER)  is catalyzed by Pt black.  Ir black and Pt black are high purity, high surface area catalysts. This H₂ is then collected and available as fuel.  The Pt and Ir used to construct the PEM electrodes are platinum group metals (PGMs).  PGMs are widely used industrially, but very scarce and expensive.  Reducing the amount, or load, of the PGMs, especially Ir, is achieved by "thrifting," a term that describes using minimum amounts of these scarce and expensive materials.  For those reasons, the developers of the PEM electrolyzers, such as Johnson Matthey and Umicore, have invested heavily to ensure that maximum amounts of the PGMs are recovered from used industrial catalysts.  Processes have also been developed for recycling the PEM polymer membrane.

Hydrogen produced by PEM electrolyzers can then be used in PEM fuel cells.  The PEM fuel cells perform the reverse reaction from the electrolyzer, taking the H₂ entering the anode, where it is oxidized to H⁺, i.e. protons, and electrons.  The anode is the Ir-based catalyst.  The protons and electrons then move to the cathode, the Pt-based catalyst, by different paths.  The protons react with the oxygen fed to the cathode to form water.  The electrons traveling through an external circuit create energy.[xiii] The only by-products of this process are water and heat.  If renewable energy is used in hydrogen generation, the entire process from producing the hydrogen through its end use creates zero carbon emissions.  Umicore reports: “…PEM fuel cells have been successfully tested in the toughest conditions, extreme cold or heat, storms, and hurricanes.  It is no surprise that companies look at this technology for backup power purposes as these fuel cells allow you to go off-grid.” [xiv]

Grades of Hydrogen 

Different grades of hydrogen are specified for different uses.  For example, Grade D hydrogen, which is very high purity, is used to power PEM fuel cell vehicles.  The International Standards Organization (ISO) developed the written standard, ISO 14687, Hydrogen Fuel Quality – Product Specifications.  This document was created, along with normative references, ISO 21087[xv] and ISO 19880-8[xvi] to give hydrogen producers, suppliers, and users detailed information on the quality testing needed for the hydrogen used in PEM fuel cell vehicles.  Quality testing of the hydrogen entails determining if defined impurities are below the allowed threshold limits.  Certain impurities, like water, helium, or argon, only cause a dilution of the hydrogen gas and are permitted at relatively high levels.  Other impurities, such as carbon monoxide, sulfur compounds, formaldehyde, and several others, will poison the catalysts, thereby decreasing the life of the fuel cell.  That is a costly problem.  The National Physical Laboratory (NPL) in Great Britain in conjunction with other National Metrology Institute (NMIs), government agencies, and commercial laboratories, have developed hydrogen quality standards for testing for the impurities stated in ISO 14687.  A review and survey of the analysis methods established and validated for over ten years for impurity testing was published in 2021.[xvii]

How is Inorganic Ventures participating in and contributing to the growing Hydrogen Economy?  We are a Certified Reference Material manufacturer of mainly aqueous standards.  While the Hydrogen Quality standards developed for testing the hydrogen used in PEM fuel cell vehicles are gaseous reference materials, the requirements for certified reference materials still follow the same ISO 17034 and ISO 17025 references that we have been accredited to.  As the hydrogen economy expands we are exploring ways that we might be able to supply Hydrogen Quality testing laboratories in the US with the standards that meet the requirements for testing the hydrogen used in PEM fuel cell vehicles.  We are dedicated to supporting areas where accurate standards are required and helping create a safer world for future generations!