PAYNE INSTITUTE COMMENTARY SERIES: COMMENTARY

By Anna Littlefield and Siddhant Kulkarni

Link to Part 2: Policy, Regulatory, and Market Viability

October 24, 2024

As global efforts to decarbonize the economy intensify, hydrogen is emerging as an important component of the clean energy transition. While significant advancements have been made in electrification, renewable energy, and energy storage, these technologies alone are not enough to reach net-zero emissions. Many sectors are difficult, if not impossible, to fully electrify, indicating that alternative fuels like hydrogen will play an indispensable role in the green economy. Hydrogen offers a versatile, low-carbon solution that addresses the limitations of electrification in sectors like heavy industry and transportation, making it a critical tool in the global push toward sustainability.

The Bipartisan Infrastructure Law dedicated $9.5 Billion in funding to hydrogen research and led to the publication of the U.S. National Clean Hydrogen Strategy and Roadmap in June of 2023. This report highlights the importance of targeting hydrogen applications in hard-to-decarbonize sectors such as industrial emitters, heavy-duty transport, maritime, aviation, and power generation. Federal Investment through the Hydrogen and Fuel Cell Technology Office has led to the creation of six hydrogen research consortiums, over 1300 hydrogen-related patents, and several demonstration projects. This substantial backing underscores hydrogen’s central role in the nation’s clean energy strategy.

So Why Hydrogen?
As the most abundant element in the universe, hydrogen is poised to play a transformative role in the global energy transition. Hydrogen has traditionally been derived from fossil sources, but new technologies are emerging to produce hydrogen with zero emissions. Unlike fossil fuels, hydrogen itself does not release greenhouse gases when used as fuel. Opportunity for innovation exists in its production methods, that vary significantly in their environmental impact. Here we seek to demystify hydrogen in its role as a clean energy carrier and the different ‘colors’ assigned to hydrogen based on production pathways.
To fully understand hydrogen’s potential in the future energy landscape, it is crucial to distinguish between hydrogen production methods, its wide-ranging applications, and challenges associated with storage and transportation.

How do we produce Hydrogen?
Hydrogen ‘production’ is perhaps a misnomer, as hydrogen exists in naturally occurring chemical compounds like water (H2O), methane (CH4), and biomass (C6H12O6+H2O), and simply needs to be isolated. The production of hydrogen therefore involves separation of hydrogen molecules via electrolysis (splitting water into hydrogen and oxygen), steam-methane reforming (extracting hydrogen from natural gas), pyrolysis (thermal processing to produce hydrogen and solid carbon from methane), and gasification (converting organic material at high temperatures, without combustion, into carbon monoxide, hydrogen, and carbon dioxide). All methods for splitting/separation/cracking involve energy, and the energy source powering these methods further complicates the many designations of hydrogen.
Electrolysis is a key pathway for hydrogen production, offering a clean and potentially scalable method for generating hydrogen. By splitting water into hydrogen and oxygen using electricity, electrolysis produces no direct emissions, assuming the process is powered with renewable sources. Hydrogen produced this way is referred to as “green” hydrogen and is highly favored by clean energy advocates. However, challenges remain, particularly in terms of cost and a lack of infrastructure, hindering widespread adoption. Despite its environmental promise, electrolysis is energy-intensive, and the use of renewable energy is essential to maintain the green designation.

Figure 1: The classification of hydrogen by color reflects the carbon intensity of its production process.

Hydrogen produced through coal gasification, commonly known as “black” or “brown” hydrogen depending on the type of coal used, is one of the most carbon-intensive production methods. Black hydrogen, derived from bituminous coal, and brown hydrogen from lignite both generate substantial CO₂ emissions, with estimates suggesting that roughly 19 tons of CO₂ are produced for every ton of hydrogen (per the Belfer Center). Though gasification can be applied to various carbon-based feedstocks, coal gasification remains a major contributor to industrial emissions.

In contrast, “blue” hydrogen is produced from natural gas through a process called steam methane reforming (SMR). While it still generates CO₂, the emissions may be mitigated through carbon capture and storage (CCS) technologies. However, this method is not entirely carbon-free, leading to debates about its role in a sustainable energy future. Critics argue that while “blue” hydrogen offers an improvement over “black” and “brown” hydrogen, it risks perpetuating dependence on fossil fuel infrastructure, making it a less-than-ideal solution for long-term decarbonization.

“Turquoise” hydrogen is a more recent production technique, generated via methane pyrolysis. This process heats methane to high temperatures in the absence of oxygen, producing hydrogen and solid carbon as byproducts. Unlike grey or blue hydrogen, turquoise hydrogen avoids direct CO₂ emissions, and the solid carbon produced can potentially be a valuable commodity, enhancing the economic appeal of this method. Nonetheless, challenges remain in scaling and commercializing the technology.

Natural hydrogen, sometimes referred to as “white” or “gold” hydrogen, has recently attracted attention as a potential source. These naturally occurring accumulations of hydrogen, formed over geologic time beneath the Earth’s surface, can be extracted much like oil and gas. However, questions remain about the feasibility and scalability of this resource. If viable on a large scale, natural hydrogen could provide a more direct and less energy-intensive route to hydrogen production. Recent publications explore the possibility of enhancing this natural process to generate ‘orange’ hydrogen.  This would entail injecting carbon-enriched solution into reactive formations in the subsurface and recovering hydrogen from the produced fluid, rather than simply exploring for existing accumulations.  Figure 1 outlines both the common hydrogen production pathways and includes some of these more ‘obscure’ methods of generation.

How do we use Hydrogen?
Hydrogen is emerging as a versatile tool for the energy transition with significant potential across multiple sectors, such as transportation, decarbonizing hard-to-abate industries, power generation, and industrial production. In transportation, hydrogen fuel cells generate electricity through an electrochemical reaction producing only water vapor as a byproduct, compared to traditional combustion, which produces CO₂ and other emissions. Hydrogen looks particularly promising for long-haul trucking and heavy-duty transport, where battery-powered electric vehicles are limited in range and payload. Hydrogen-powered fuel cell vehicles (FCEVs) provide greater range, faster refueling, and the ability to carry heavier loads, making them ideal for freight. Moreover, hydrogen derivatives like ammonia are being explored as a clean fuel for rail and marine sectors, offering zero-carbon alternatives to diesel engines and fossil fuel-based marine fuels. Ammonia can be used in fuel cells to power electric trains, and its high energy density makes it well-suited for long voyages in the shipping industry.

Hydrogen can also support the decarbonization of high-heat industrial processes. In steel manufacturing, for instance, hydrogen can be used to replace coal in blast furnaces, providing the intense heat required without producing CO₂ emissions.  Similarly, hydrogen can be used to generate the heat needed for cement kilns and decrease emissions associated with the second-largest source of global industrial emissions.

Hydrogen is also playing an increasing role in power generation. Hydrogen fuel cells can provide continuous electricity for grid-scale applications or as backup power, especially useful for stabilizing the energy grid in conjunction with intermittent renewable energy sources like wind and solar. Additionally, hydrogen can be blended with natural gas in existing power plants, gradually reducing emissions without requiring major infrastructure changes. As hydrogen production scales up, it is expected to replace an increasing share of natural gas in these systems. 

As an energy carrier, hydrogen enables the storage and transport of renewable energy. Surplus electricity generated from renewable sources can be converted into hydrogen via electrolysis and stored for later use. This hydrogen can be converted back into electricity when demand is high, balancing the intermittency of renewable energy and providing long-duration energy storage. Hydrogen offers further flexibility as it can be transported through pipelines or shipped as a liquid, allowing regions with abundant renewable energy resources to supply energy to areas with higher demand.

In industrial processes, hydrogen remains indispensable, particularly in chemical production. The Haber-Bosch process for ammonia synthesis, which accounts for more than half of global hydrogen consumption, uses hydrogen as a key input for producing fertilizers. Hydrogen is also used in oil refining, where it helps remove sulfur from fuels, producing cleaner-burning products. As hydrogen technologies advance and costs decrease, applications across these sectors will continue to expand, supporting the global transition to a sustainable and low-carbon economy (see Griffiths et al. for an exhaustive review on this topic).

How do we transport and store Hydrogen?
Establishing storage and transportation infrastructure is critical for developing a flexible and reliable hydrogen economy.  While there are multiple methods available, compressed gas hydrogen is the most common storage method, where hydrogen is stored in high-pressure tanks at 350-700 bar and transported via specialized tube trailers or pipelines.  This approach requires robust infrastructure and is necessary due to the low energy density of hydrogen gas.

Alternatively, liquid hydrogen offers higher density storage but requires cryogenic temperatures (-252.8°C).  Insulated tanks are used for storage, and special cryogenic tankers are needed for transport. Liquid hydrogen is more efficient in long-distance, bulk transportation, but the energy-intensive liquefaction process and losses due to boil-off are significant drawbacks.  

Chemical carriers offer a promising alternative to traditional hydrogen storage and transport methods, addressing challenges associated with both compressed and liquid hydrogen. Transporting hydrogen as ammonia (NH₃), for instance, can utilize existing infrastructure due to its liquid state at ambient temperatures, making it an attractive and cost-effective option. Similarly, hydrogen can be transported as methanol (CH₆OH), which can be produced from renewable sources, and Liquid Organic Hydrogen Carriers (LOHCs), which can reversibly absorb and release hydrogen.  The improved safety and ease of handling has attracted attention to these chemical carriers; however this method requires additional processing to release hydrogen at the point of use, which can reduce overall system efficiency.

The choice of storage and transportation methods depends on factors such as transport distance, storage duration, and specific needs of the application. As research progresses, these technologies are becoming increasingly important in building a robust hydrogen economy. Similarly to the different production pathways, these transportation and storage methods present distinct advantages and limitations, the ideal solution depends on application requirements and existing infrastructure.

Conclusion
Despite the potential that hydrogen holds in decarbonizing hard-to-abate sectors and as a flexible energy carrier, the industry faces an uphill battle. In addition to solving cost and infrastructure challenges, earning and keeping public trust will be critical.  A recent Xcel Energy demonstration project in Colorado was halted after public pushback on the energy provider’s plan to mix hydrogen into natural gas lines. There is still minimal familiarity with hydrogen as a fuel or energy carrier for most of society, making education, outreach, and engagement critical in these early stages.

While obstacles remain, hydrogen’s adaptability across industries makes it an important tool for reducing emissions and supporting a low-carbon future. Continued investment and innovation could unlock hydrogen’s potential in the remaking of our energy landscape, and critically must include societal and environmental considerations from the outset (see part two for a discussion of hydrogen policy, regulation, and viability).

ABOUT THE AUTHORS

Anna Littlefield, Payne Institute CCUS Program Manager and Research Associate
PhD Student, Geology and Geological Engineering, Colorado School of Mines

Anna Littlefield is the Program Manager for Carbon Capture Utilization and Sequestration for the Payne Institute at the Colorado School of Mines. As a current PhD student in the Mines geology department, her research focuses on the geochemical impacts of injecting CO2 into the subsurface as well as the overlap of geotechnical considerations with policymaking. Anna joins the Payne Institute with 8 years’ experience in the oil and gas industry, where she worked development, appraisal, exploration, new ventures, and carbon sequestration projects. Her academic background is in hydrogeology with an M.S. in geology from Texas A&M University, and a B.S. in geology from Appalachian State University. Anna is passionate about addressing both the societal and technical challenges of the energy transition and applying her experience to advance this effort.

Siddhant Kulkarni, MS Student, Mineral and Energy Economics, Colorado School of Mines

Siddhant is a student researcher at The Payne Institute at Colorado School of Mines.  Currently pursuing his M.S in Mineral and Energy Economics, his research focuses on the commercial and insurance side of CCS projects and their risk management, as well as government incentive programs and schemes promoting the use of renewable energy. Additionally, he holds a B.S Honors in Economics from Symbiosis School of Economics, Pune. He is dedicated to advancing energy transition to renewables while addressing the various societal challenges that may come with it.

ABOUT THE PAYNE INSTITUTE

The mission of the Payne Institute at Colorado School of Mines is to provide world-class scientific insights, helping to inform and shape public policy on earth resources, energy, and environment. The Institute was established with an endowment from Jim and Arlene Payne and seeks to link the strong scientific and engineering research and expertise at Mines with issues related to public policy and national security.

The Payne Institute Commentary Series offers independent insights and research on a wide range of topics related to energy, natural resources, and environmental policy. The series accommodates three categories namely: Viewpoints, Essays, and Working Papers.

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DISCLAIMER: The opinions, beliefs, and viewpoints expressed in this article are solely those of the author and do not reflect the opinions, beliefs, viewpoints, or official policies of the Payne Institute or the Colorado School of Mines.