Have you, like me, seen many references to the excitement around hydrogen as a possible zero emissions energy source? Based on a review of numerous hydrogen articles and reports, I find that many observers conclude hydrogen is best used in the near term for storage and hard to decarbonize industries.

What Is Hydrogen? 

Hydrogen is the lightest, as well as most abundant, element in the universe. The Sun, like all stars, is composed predominantly of hydrogen. On Earth, hydrogen typically exists in combination with other elements rather than separately. Commonly it combines with oxygen to form water. 

How Is Hydrogen Produced? 

Hydrogen is made through processes that separate it from the other elements with which it has combined. Traditionally hydrogen is produced using steam reforming. Steam reforming is a process in which a hydrocarbon fuel and high-temperature steam react to form hydrogen and carbon dioxide. In 2022, hydrogen producers used steam reforming of methane (the main component of natural gas) to make about 95% of all hydrogen produced. In an effort to render steam reforming cleaner, it is sometimes combined with carbon capture and storage, whereby the carbon dioxide the process produces is captured. Another process utilized for the production of hydrogen is the electrolysis of water. In this process, hydrogen atoms are separated from oxygen atoms through the application of energy to water in an electrolyzer. The electrolysis produces oxygen as a byproduct but no carbon dioxide. If the energy used for the electrolysis is derived from renewable resources, the resulting hydrogen is referred to as green hydrogen. Hydrogen produced through steam methane reforming has been designated grey hydrogen. Blue hydrogen refers to hydrogen made through steam reforming combined with carbon capture and storage. 

How Is Hydrogen Used? 

The use of hydrogen for energy is not new. In the 1960s, NASA used hydrogen to fuel rockets in its space program and in fuel cells on board spacecraft. Today, hydrogen is predominantly used in oil refining and the production of chemicals, such as fertilizers. Similar to NASA’s use of hydrogen, hydrogen can be used as a combustible fuel to power vehicle engines similar to gasoline-fueled combustion engines. Hydrogen internal combustion engine vehicles are being developed. Hydrogen can also power fuel cell electric vehicles. This technology has been applied in the transportation sector, where hydrogen fuel cells now power a significant number of forklifts, buses, and passenger cars. 

Promoted Applications

Transportation 

Some stakeholders promote the expanded use of hydrogen in the transportation sector. Hydrogen internal combustion engines produce small amounts of carbon dioxide (through the combustion of some motor oil) and (like gasoline-fueled internal combustion engines) nitrogen oxides. Nitrogen oxides can have negative health effects, as well as contribute to acid rain and indirectly to global warming. As an additional disadvantage, hydrogen has a low energy density, which means hydrogen internal combustion engine vehicles require large quantities of hydrogen. A large onboard storage tank is also necessary, and the gas must be stored under very high pressure (which poses a safety hazard). Hydrogen fuel cell electric vehicles share this disadvantage with hydrogen internal combustion engine vehicles. In contrast with hydrogen internal combustion engine vehicles, however, hydrogen fuel cell electric vehicles use hydrogen more efficiently. As to byproducts, in hydrogen fuel cell electric vehicles, the hydrogen is combined with oxygen, whereby only energy and water are produced. Nevertheless, supporters of electric vehicles powered by electricity from the power grid argue that hydrogen fuel cell electric vehicles are an inferior choice because it is more efficient to power vehicles using electricity in the first instance rather than use the electricity to produce hydrogen to in turn fuel vehicles. 

Heat and Power 

Some in the fossil fuel industry and trade associations support the use of hydrogen in homes and commercial buildings. Specifically, they seek to blend hydrogen with natural gas used for heating and cooking. Similar entities advocate for blending hydrogen with natural gas in gas-fired power plants. The advantage of blending hydrogen with natural gas is that the combustion of the hydrogen does not produce carbon dioxide. (The combustion of the natural gas does of course produce carbon dioxide.) Advocates of blending hydrogen with natural gas assert that the existing natural gas infrastructure can be advantageously utilized for hydrogen. Critics, however, argue that equipment within that infrastructure would need to be retrofitted to accommodate the addition of hydrogen. These same critics point out that safety concerns significantly limit the amount of hydrogen that can be blended with natural gas to perhaps no more than 20% of the blend. Such safety concerns impact how much carbon dioxide emission reduction can be achieved by blending hydrogen with natural gas. 

Promising Applications 

Despite efforts to promote the above applications of hydrogen, many believe that the best uses of hydrogen in the near term are for energy storage and hard to decarbonize industries, such as long-distance trucking, aviation, and maritime shipping, as well as those involving high-heat industrial processes. Among proponents of these applications, many specify that the hydrogen used should be green hydrogen because its production does not create carbon dioxide. As countries and companies have taken steps to reduce their carbon dioxide emissions, they have in some instances chosen electrification (converting systems or machines to use electrical power). However, for processes requiring very high temperatures, such as steelmaking, electricity cannot produce sufficient heat. Similarly, electricity poses difficulties for heavy-duty transport. Long-distance trucking requires rapid refueling or recharging, which electricity cannot provide. Other modes of transportation, such as maritime shipping and aviation, require sufficient energy to reach destinations without refueling. Using hydrogen for energy for these applications can avoid the limitations of electricity. In addition, many support the use of hydrogen for energy storage. Applied this way, hydrogen can address intermittency concerns associated with renewable energy. 

Challenges of Promising Applications 

While energy storage and hard to decarbonize industries are promising applications for green hydrogen, these applications do have challenges to overcome. These challenges involve cost, scale, energy, water, transportation, storage, and safety. 

Cost and Scale 

Using green hydrogen for energy storage and hard to decarbonize industries requires significant capital investments. The expense of renewable energy for the production of green hydrogen also impacts cost. In addition, the production of green hydrogen presents issues of scale. As a newer technology, only a relatively small number of facilities for the production of green hydrogen are in operation. However, many more of these facilities are planned. The completion of these projects would scale up green hydrogen production with the expected effect of lowering the cost of green hydrogen. 

Energy 

The amount of energy required to produce green hydrogen raises concern. The energy-intensive nature of electrolysis appears to be a significant factor supporting the conclusion among many that green hydrogen is best reserved for hard to decarbonize industries and energy storage. For industries suitable for electrification, using electricity at the outset is more efficient than instead using energy-intensive electrolysis to create hydrogen to power such industries. Furthermore, using renewable energy for electrolysis, it is argued, should be done strategically so as not to diminish the supply of renewable energy for other originally intended uses. Such diminishment could lead to the production of nonrenewable energy for such intended uses. 

Water 

As fresh water is essential for the production of green hydrogen through electrolysis, water scarcity poses a challenge for this technology. Those skeptical about the technology emphasize the significant quantities of fresh water required for the production of green hydrogen. The production of blue and grey hydrogen using steam methane reforming also requires water but approximately half as much as required for electrolysis. Hydrogen producers can use desalination in some locations experiencing water scarcity. Desalination, however, is a costly and energy-intensive process. Researchers are investigating methods by which seawater (which constitutes over 96% of Earth’s water), or even wastewater, could be used for producing green hydrogen through electrolysis. 

Transportation, Storage, and Safety 

Following the creation of green hydrogen, its producers encounter issues relating to the transportation, storage, and safety of hydrogen. Notably blue and grey hydrogen share these disadvantages with green hydrogen. Natural gas infrastructure cannot be used for the transportation and storage of hydrogen without modification to equipment. Moreover, significant expansion in the use of hydrogen would require the development of extensive hydrogen infrastructure. The characteristics of hydrogen (specifically being the lightest and smallest element) make hydrogen difficult to contain. This difficulty consequently raises concerns over leaks and safety. 

Support for Hydrogen 

Prompted by the perceived need to develop alternative fuels for the world’s growing energy needs, and despite the disadvantages of green hydrogen and hydrogen generally, the United States and other countries have moved forward with efforts to develop the hydrogen industry. 

U.S. Support 

On June 7, 2021, the U.S. initiated its Hydrogen Shot, a Department of Energy (DOE) program which aims to reduce in one decade the cost of clean hydrogen to $1 per kilogram. The program also seeks to address the challenges facing clean hydrogen. (DOE uses the term clean hydrogen. The 2021 Infrastructure Investment and Jobs Act, commonly referred to as the Bipartisan Infrastructure Law, requires DOE to define clean hydrogen as hydrogen produced with a carbon intensity equal to or less than two kilograms of carbon dioxide equivalent produced at the site of production per kilogram of hydrogen produced.) The Bipartisan Infrastructure Law appropriated $9.5 billion for clean hydrogen. Of this, $8 billion was allocated for six to ten regional clean hydrogen hubs. These hubs are defined as a network of clean hydrogen producers, consumers, and connective infrastructure located in close proximity to one another. Other funds were allocated to improve the cost-effectiveness and efficiency of electrolysis technologies, as well as for the research, design, development, and demonstration of cost-effective and efficient clean hydrogen equipment. 

Last year, the Inflation Reduction Act contained a tax credit for the production of qualified clean hydrogen, defined as hydrogen that is produced through a process that results in a lifecycle greenhouse gas emissions rate of not greater than four kilograms of carbon dioxide per kilogram of hydrogen. In addition, last September DOE released its draft National Clean Hydrogen Strategy and Roadmap for public comment. 

International Support 

Other countries are also taking steps to support the development of hydrogen as an energy source. According to the International Energy Agency, over two dozen countries have adopted national hydrogen strategies with a third of the strategies being adopted in the last two years. Additionally, countries are proceeding with implementation, as demonstrated by Germany’s H2Global Initiative and the EU’s Important Projects of Common European Interest. The EU has established goals for constructing electrolyzers, with Spain and Denmark among the countries with plans for such construction. Saudi Arabia is building a green hydrogen production facility as well. Recently, the EU outlined its plans to establish a European Hydrogen Bank, which will invest in European green hydrogen assets.The development of the hydrogen industry also seems likely to benefit from international cooperation. In September of last year, at the Hydrogen Energy Ministerial Meeting in Tokyo, over 20 countries agreed to boost their production of low-emission hydrogen. 

Private Support 

The past few years have also witnessed a rise in private support for hydrogen. In 2017, the Hydrogen Council was formed at the World Economic Forum in Davos with Air Liquide, Toyota, and Shell among the Council’s founding 13 members. Its membership has since grown to nearly 140 companies. The Council’s stated purpose is to help limit global warming and to facilitate hydrogen’s role in the energy transition. Specifically within the aviation industry, ZeroAvia, Otto, Airbus, and Universal Hydrogen are all working on hydrogen fuel cells for aircraft. As further evidence of growing private support for hydrogen, last year Amazon entered into a seven-year $2.1 billion agreement with Plug Power, which supplies hydrogen fuel cells and green hydrogen for electric forklifts. 

Prospects for Hydrogen

Growing support for hydrogen increases the likelihood of overcoming its challenges as an energy source. The current average cost for one kilogram of green hydrogen is approximately $5. Averaging estimates for the possible reduced cost of green hydrogen achievable by 2030 yields a cost of $2. If technological advancements address hydrogen's challenges, such as cost, the use of hydrogen (particularly green hydrogen) for hard to decarbonize industries and energy storage could contribute measurably toward countries’ attainment of their emission reduction goals. 

SOURCES 

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Carbon Tracker. (2022, October 20). Clean Hydrogen’s Place in the Energy Transition. Retrieved from https://carbontracker.org/reports/clean-hydrogens-place-in-the-energy-transition/ 

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