Hydrogen: A Fuel and Energy Storage

Diving into hydrogen: how it's used as both a fuel and energy storage.  Cat's own hydrogen expert, Steven Parente,  joins me for the discussion. 

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Transcript

Lou:  Good Day and welcome everyone to Power Bytes!  I am your host Lou Signorelli and Power Bytes is your destination Podcast for power generation conversation.  As always, please know how much we appreciate you, our listeners.  We hope you find our topics helpful and interesting.  There are several ways for you to get in touch with the show. You can send us an email at powerbytes@cat.com, visit us at Cat Electric Power on Facebook or LinkedIn.  Please remember to subscribe, follow, and comment on your experience today, it really does help.

Lou: You may recall an episode from April of 2021 titled "Fuels of the Future" where we briefly touched on a variety of fuels that rest on the horizon.  Today we are going to dive a bit deeper into one such fuel, and that fuel is Hydrogen.  So, joining me today is Caterpillar's resident expert on the topic Steven Parente.  Steven is Hydrogen Infrastructure and Integration Specialist at Caterpillar with responsibility for defining new products and technical sales support of hydrogen infrastructure products.  He has spent more than 16 years in the hydrogen industry where he has gained subject matter expertise in hydrogen production, compression, storage, and dispensing.  Steven is a registered professional engineer; he hold a B.S. in Chemical and Biomolecular Engineering and a Master’s in Business Administration, both from the Georgia Institute of Technology.
Lou: Welcome Steven
Steven: Thank you, Lou.  I'm excited to be here and to help demystify hydrogen for our listeners.
Lou:  Steven, anyone that has any interest in hydrogen knows that it is a common element.  One that can be derived from water using an electrolyzer.  But many believe that there are many more uses of hydrogen in a variety of forms whether it be liquid or gas.  There are two aspects that I'd like to talk about: First: hydrogen as a fuel, and next hydrogen as an energy carrier.  Talk with me for a moment about Hydrogen as a fuel and where it's used today.
Steven: There is indeed a hydrogen industry today.  Globally, upwards of 100 million metric tons of hydrogen are produced every year, largely for industrial consumers.  Refineries are the largest consumer of hydrogen using it for upgrading fuels in processes like hydrocracking.  It's used as an input to the production of ammonia which is used in fertilizers.  Hydrogen is also used in various chemical processes and to a lesser extent in processes like steel mills, semiconductor fabrication, and so on.  These are largely all industrial applications.
However, a lot of the talk today centers around using hydrogen to achieve deep decarbonization in other sectors where electrification is difficult: mobility & transportation and power generation for example.  To some degree, hydrogen is used in these applications today but it's very limited and on a much smaller scale when compared against fossil fuels.

Lou: I don't know how many recognize just how useful hydrogen is in those industries.  100 Million metric tons is nothing to laugh at!  How do these industries get their Hydrogen?

Steve: The largest consumers of hydrogen are generating on-site.  Hydrogen is a very reactive molecule and is not found freely in nature.  To obtain hydrogen, we have to extract it from another molecule.  Today, hydrogen is extracted predominantly from fossil fuels, such as natural gas.  So most industrial consumers, those consuming relatively large volumes of hydrogen and consuming on a fairly continuous basis, have a dedicated plant on their property which they operate and produce hydrogen for their processes.  Alternatively, they contract a supplier such as an industrial gas company to own and operate a plant and send the gas to them.  But in either case, the plant is located on the consumer's property or just adjacent to it.  For smaller volumes of hydrogen or for those consumers that need it on a more infrequent basis, they may receive deliveries in the form of gas or liquid.  For example, most refueling stations for fuel cell electric vehicles, both private and retail, would receive hydrogen deliveries.  These consumers would have on-site storage that a hydrogen supplier like a gas company, monitors and fills on a regular or as-needed basis.

Lou: It would seem to me that if we are to use hydrogen for mobility and transportation as you mentioned earlier, we are going to need a much greater means of distribution.  What do you see going on in this area?

Steve: That's right, Lou.  If we're going to see the expansion of a hydrogen economy then we expect that a more developed distribution model is needed similar to what we see for natural gas today.  This means development and expansion of hydrogen pipelines and the ability transport hydrogen on ships.  Let's start with pipelines.  There are a few hydrogen pipelines in existence today, but they are pretty limited in scope and a fraction of natural gas pipeline length.  There is a lot of talk about re-purposing natural gas pipelines for hydrogen but this option presents some challenges.  Hydrogen can accelerate failure modes of some steels and elastomers used in natural gas pipelines, so converting a pipeline is not expected to be as simple as pulling natural gas out and putting hydrogen in.  However, we see a lot of government policy and incentives being put toward the development of hydrogen production clusters or hubs.  For example, in the U.S., the Infrastructure Investment and Jobs Act set aside $8.5 billion for the creation of about 6 – 10 hydrogen hubs throughout different regions of the country.  Pipelines are a component of several of the hub proposals, and the creation of these hubs may incentivize their interconnection through additional pipelines.
Another piece of the distribution puzzle is ship transport.  Shipping is an essential component of natural gas distribution today, where its transported in a liquid form, LNG.  There are several countries especially those with abundant renewable resources that are exploring the possibility of being hydrogen exporters in the future.  However, there is no infrastructure today for ocean transport of hydrogen.  There are no hydrogen bunkers at ports, and there are no commercial available ships for liquid hydrogen transport.  For this reason, the industry is exploring the concept of hydrogen carriers.  That is, shipping hydrogen in the form of another molecule.  The most talked about hydrogen carriers are ammonia, methanol, and a category of hydrocarbons termed Liquid Organic Hydrogen Carriers or LOHC.  The advantage of all of these options is that they are globally traded commodities today, so storage vessels, port bunkering and transport ships are already available.  In addition, these carriers feature densities greater than that of liquid hydrogen so more hydrogen could be transported in each shipment.  The downside is that synthesizing carrier molecules and later extracting hydrogen from those molecules is an even more energy intensive option than producing and consuming hydrogen directly.

Lou:  Steve, something you said caught my attention…. Hydrogen accelerates failure modes in steels?  What has to be done to steel to make it durable in the face of hydrogen?

Steve:  I was making reference to a number of failure mechanisms that fall under the term of "hydrogen embrittlement."  There are three elements you need for embrittlement: you need a hydrogen environment, a susceptible material, a stress on the material.  When I say hydrogen environment, it's not as simple as just containing hydrogen.  In fact the concentration of hydrogen and the pressure of the hydrogen-containing gas are significant factors which determine whether embrittlement will occur.  This is one of these reasons that when you hear talk of hydrogen blending in pipelines, the discussion is around 25% hydrogen blends.  This 25% limitation represents a level of conservatism where the industry expect existing pipelines, equipment, and components will not experience hydrogen embrittlement to any significant degree.  
Now for 100% hydrogen pipelines, the level of impact will still depend on the pipeline pressure and the stresses on the pipe.  In cases where there is a concern, the best defense against hydrogen embrittlement is to select inherently safer materials of construction.  That could mean that retrofitting natural gas pipelines or at least portions of those pipelines represents a significant capital expense.  But I would emphasize that the case is not closed on this topic.  It's an area of active research and investigation.  

Lou:  Once Hydrogen is removed from these other molecular compounds like water or natural gas, how stable is it.  If we are talking about using it as a power source, is it inherently safe?

Steve:  Hydrogen is a stable molecule, but it's also highly reactive and readily combustible.  The starting point of any safety analysis is to identify and appreciate the hazards that can result from the properties of hydrogen.  Hydrogen hazards are similar to other flammable gases such as natural gas.  However, in comparison to natural gas, hydrogen has a wider flammability range, requires less energy to ignite, and hydrogen flame fronts can travel much faster than natural gas leading to a greater risk of detonation/explosion.  Despite these risks, there is also a body of experience, particularly in industrial sectors like oil & gas and chemical processing, that hydrogen systems can be designed and operated safety.  The industry has mitigated these known hazards through several strategies such as regular inspection and leak testing, implementing fault tolerant safety controls, and designing in fire and gas detection systems just to name a few.  Another important property is that hydrogen is a light molecule, far lighter than air.  So it experiences high buoyancy when released—it will generally disperse upwards.  For this reason, there is a preference to install hydrogen systems outdoors, or to employ a high degree of ventilation if brought indoors.  Safety is a central topic in the evaluation of hydrogen projects, and I would encourage our listeners who are interested in or evaluating hydrogen opportunities to begin the discussion with their EHS teams around safety planning for hydrogen systems.  

Lou:  A bit ago you mentioned the distribution challenges facing broader use of hydrogen.  Given the embrittlement issues, how easy will this to be to overcome?

Steve: Hydrogen embrittlement is a complicated series of failure mechanisms very dependent on the specific operating environment.  There is still a lot of study being done on the readiness of natural gas pipelines to accept hydrogen, and there is a possibility that less retrofitting is required than we might expect.  Also, there's research being done on novel methods of hydrogen storage and the possibility of hydrogen carriers that I mentioned previously.  So yes, distribution is a significant challenge, but there are solutions coming into focus.

Lou: Steven, if we were to compare hydrogen to Natural gas for the purpose of power generation, are there advantages to using hydrogen?

Steven:  The main advantage to using hydrogen over natural gas for power generation is reducing or possibly even eliminating carbon emissions.  Hydrogen is an alternative fuel, available today, to help an organization make progress on its ESG goals.  When hydrogen is used in a recip engine, it produces significantly reduced NOx and minimal carbon emissions that come from oil carryover.  In the future, hydrogen used in fuel cells can achieve zero emissions at the tailpipe.

Lou: There you have it folks.  I'd like to thank Steven Parente for sharing his expertise with us today…. And thank you, our listeners for joining us on Power Bytes.  You can find Cat Electric Power on Facebook or LinkedIn.  Be sure to subscribe, like, comment and share Power Bytes wherever you listen to your podcasts.  Until next time, have a great rest of your day!