As more process industries look for ways to decarbonize, hydrogen is increasingly part of the conversation. Tushar Chitre, process technology manager for Burns & McDonnell in Canada, offers some perspective on how ammonia could play an increasingly important role in helping hydrogen become part of the clean energy mix.
A: I was born into a family with many accountants and bankers, so numbers came very naturally. However, from a very young age, I found myself curious about how things worked, and soon learned that numbers can be very helpful in solving those problems. This attracted me to engineering and I ended up becoming a chemical engineer.
Early in my career, I had an opportunity to work in the technical services department of a petrochemical company. The management there gave me an opportunity to set up a new world-scale unit tasked with technology comparisons and techno-economic analysis. I found this pathway very much to my liking and I would say it was a big factor in driving a lifelong fascination with technologies.
A switch from the petrochemical industry to oil and gas introduced me to the vast field of refining technologies and presented me with the opportunity to manage multibillion-dollar refinery projects in many places around the world. This was a very fulfilling experience in a number of ways, including giving me an opportunity to nurture my passion for travel and visiting some of the world’s most exotic places.
More recently, with the worldwide push toward renewables and decarbonization, I began working for a major renewable energy technology licensor and specialized in hydrogen, ammonia, renewable diesel and sustainable aviation fuel (SAF) technologies.
A: Ammonia has a long history, going back many decades in a number of manufacturing applications. It has been a critical component for fertilizer manufacturing and in fact most ammonia produced today is used by the fertilizer industry.
Traditional ammonia manufacturing requires a basic two-step process. The first involves hydrogen production utilizing steam methane reforming (SMR) of natural gas or other fossil-based feedstock, followed by a second step involving a high-pressure ammonia loop using Haber-Bosch process.
Over the years, demand for ammonia has lined up with fertilizer demand. However, with decarbonization technologies emerging, ammonia has gained momentum for its potential as a carrier fluid for hydrogen. This concept basically involves producing hydrogen, then converting it to ammonia so it can be more easily stored and/or transported, and then converted back to hydrogen for end-use applications.
A: Ammonia is an inorganic compound and does not contain a carbon atom, so it can play a number of interesting roles as we look for pathways to reduce carbon emissions. Hydrogen has gained a lot of attention as a clean energy alternative to fossil fuels, but transportation and storage of hydrogen is a major hurdle. As the lightest compound, hydrogen does not pack the density of fossil fuels, meaning that it must be stored and transported either at very high pressure or in a deep cryogenic state. This results in increased cost considerations for storage and transport, as most hydrogen currently is produced and used on-site.
Ammonia (NH3) has a high percentage of hydrogen content — one nitrogen atom to three hydrogen atoms — but does not require the same high pressures or cryogenic cooling for storage and transport. Storage and transport of ammonia is relatively easy and has been practiced for several decades. This makes ammonia very attractive as a hydrogen carrier because it can solve a number of cost and safety concerns.
A: Japan and Korea are leading the way in developing an ammonia economy. These are regions that have historically imported natural gas, coal and oil for power production and other industrial uses, so they are quickly pivoting toward ammonia as an economically viable means to make major headway in decarbonization. In fact, most ammonia projects that have been announced in North America and Australia have been for export of ammonia to East Asia. This trend is widely expected to soon expand to Europe and China.
Another trend affecting this bullish outlook is the potential of using ammonia directly as a fuel without the interim step of converting back to hydrogen. A number of major turbine and boiler manufacturers are now working on use cases, and in fact Mitsubishi Heavy Industries recently announced that it had successfully completed a combustion test using ammonia in a single burner application.
A: The various rainbow colors assigned to hydrogen and ammonia are not exact as they are loosely based on the production process followed and the feed used. Those designations are being increasingly replaced by Carbon Intensity (CI) scores. The Ammonia Energy Association (AEA) along with its members are trying to arrive at uniform methodologies to assign the appropriate CI number to ammonia produced. All the incentives announced in North America are based on the quantity of CO2 released per quantity of hydrogen produced (Kg CO2 / Kg H2). This formula serves as the basis for CI scores that are replacing the color classifications.
Still the colors remain somewhat helpful in explaining the various processes used.
Most large-scale ammonia projects announced in North America are in the blue category, where natural gas or a similar fossil fuel is the primary feedstock, and then carbon emissions are captured and sequestered. Green ammonia is the widely used color classification for a clean energy process that involves using electrolyzers powered by some form of renewable energy to convert water into hydrogen, and then processed further into ammonia.
In Canada, Alberta seems to be particularly well suited for blue ammonia projects as infrastructure already exists for natural gas supply. There is also ample pipeline capacity to transport captured CO2 to other locations for sequestration or uses like enhanced oil recovery. Additionally, export terminals on the coast of British Columbia could be utilized for transport of ammonia to East Asia markets. In Eastern regions of Canada, most ammonia projects fall into the green category due to an abundance of renewable energy resources. Proximity to European markets is an attractive feature for these Eastern Canada projects.
A: Of course, every technology comes with its own set of challenges and ammonia is no exception. There are really two major hurdles that must be overcome in order for ammonia to become a significant player in decarbonization.
The first hurdle is conversion of ammonia back to hydrogen at the end-use stage. This additional step really impacts both capital and operational expenses, pushing up the levelized cost of hydrogen.
The second hurdle is utilizing ammonia directly as a fuel. Though bypassing the conversion of ammonia back to pure hydrogen sounds like an attractive option, it comes with some challenges. For example, the combustion range for ammonia is quite narrow meaning the heat produced is much lower than heat produced by fossil fuels. Another challenge is that the nitrogen atom in ammonia produces NOx during combustion. This must be addressed through some form of selective catalytic reduction.
Still, despite the hurdles, ammonia is clearly on the radar as a viable energy source. Decarbonization is creating an unprecedented environment for innovation and engineering ingenuity, leading to much excitement over the potential for new technologies and process improvements. The process technologies that emerge to make ammonia a viable energy source will be interesting to watch.
Renewable fuels and chemicals are important pathways to help many sectors achieve decarbonization goals.