The transport sector is responsible for harmful emissions that cause severe problems to public health. In the European Union, vehicles release around 25% of the total harmful emissions. Green hydrogen has revolutionized transportation as an emission-free alternative to conventional internal combustion engines in fuel cell engine vehicles. It is a major constituent of a fully renewable energy model and is considered the key to changing the structure of the energy sector.
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There is growing interest in analyzing green hydrogen to assess the possible role of hydrogen in the development of the transport industry. This article will examine the benefits of green hydrogen while discussing the different challenges and modern developments in this field.
The Utilization of Green Hydrogen in the Transportation Sector Yielding Significant Advantages
Green hydrogen is a renewable energy source advantageous for almost all industries, including the transport sector.
Utilizing green hydrogen in buses, airplanes, trucks, and ships can significantly reduce harmful substances' emissions and is an alternative to conventional carbon-based fuel.
From a global perspective, green hydrogen will benefit all countries, even a developed country like the United States, which still suffers from environmental pollution and transportation emissions.
Using hydrogen-based fuel cell vehicles will significantly reduce harmful tailpipe emissions, limiting the negative impacts of global warming.
Hydrogen fuel cells have the potential to significantly reduce emissions from heavy-duty vehicles, which are major contributors to transportation-related pollution and nitrogen oxide emissions in the United States.
In the UK, the transport industry accounts for nearly 34% of total energy consumption, and over 92% of this energy is derived from fossil fuels, which contribute massively to the emission of harmful greenhouse gases. No greenhouse gases are emitted when using green hydrogen as a fuel source. The burning of hydrogen only produces completely harmless water vapors.
The utilization of green hydrogen as fuel cells is finding extensive applications. In this approach, the hydrogen gas stored in the vehicle reacts with oxygen extracted from the atmosphere to generate water and electricity. This electricity is then used to charge an intermediate battery, which powers an electric motor to propel the vehicle. The only emission produced by this process is water, making it a clean and environmentally friendly transportation solution.
Advancements in green hydrogen, particularly for applications in the transport industry, have the potential to promote decarbonization and contribute to the economy. Much investment is being made in developing infrastructure for storing and distributing green hydrogen, leading to new jobs and strengthening the economy.
Aircraft propulsion based on green hydrogen is also viable for decarbonizing the aviation sector. According to a study in the International Journal of Hydrogen Energy, whether green hydrogen powers an aircraft by thermal conversion in hydrogen combustion engines or by using electrochemical conversion via fuel cells, no harmful emissions are generated. However, novel aircraft design concepts must be finalized as hydrogen propulsion requires hydrogen gas storage.
Aviation experts have found that the varying power and energy densities of hydrogen-based aircraft propulsion systems make them scalable for medium-range and long-range aircraft, while designs powered by hydrogen fuel cells might be more suitable for short-range aircraft segments.
The benefits of green hydrogen are not limited to buses, trucks, and the aviation sector; this new energy source also promotes sustainability in the shipping industry. The maritime shipping industry contributes to approximately 7–8% of global greenhouse gas (GHG) emissions, as per the journal Current Opinion in Chemical Engineering. Among the potential alternative energy sources, hydrogen is a promising fuel for reducing emissions in this sector. Many passenger ships are developing frameworks to adopt green hydrogen-based propulsion to reduce carbon emissions.
A new concept for ships involves breaking down methane into hydrogen gas along with solid carbon through a thermal catalytic decomposition process. The harmful waste is converted into solid carbon, which can be used for other purposes. In this way, green hydrogen is powering up different domains of the transport sector and paving the way for a sustainable, emission-free future.
Limitations and Major Challenges of Green Hydrogen Technology
An initial overview of green hydrogen energy suggests it is the best solution to environmental problems. However, this technology faces serious challenges, including relatively low production and storage efficiencies, high transportation and utilization costs, and safety concerns associated with H2 handling.
Green hydrogen production is primarily done using hydrolysis, whose conditions vary drastically. The different reactants used for electrolysis require varying operating conditions, including operating temperatures, pressure requirements, and catalyst requirements as highlighted in the Journal of Computational Design and Engineering. This means that there is no single choice for infrastructure, and for different chemicals, we need to have a distinct framework, and a unique maintenance plan is to be developed in each case. This makes the process costly and complex, which is a significant challenge in boosting the confidence of individuals in this technology.
Much investment is being made in green H2 production projects, yet this technology is labeled as the energy for the future rather than the present. Although concrete concepts have been demonstrated for green hydrogen storage and transportation, its cost-effectiveness is a major limitation, as highlighted in the journal Coordination Chemistry Reviews. It is not as scalable as the conventional fossil fuels in the present energy market. While hydrogen has a superior energy density by weight compared to conventional fossil fuels, it has a much lower volumetric energy density, making it less cost-effective. Many green H2-related technologies also still encounter efficiency and safety challenges, preventing them from reaching commercial competitiveness.
The materials-related challenges are also a significant cause of concern for experts working on green hydrogen systems. These challenges include limited performance in various sectors, such as low production rates and efficiency of green hydrogen, the need for additional purification processes, limited storage and transportation capacities, and low utilization efficiencies in major application scenarios. Green hydrogen production has always been carried out using very expensive materials, which demand high energy for the chemical reactions. In this way, the overall cost of producing green hydrogen has increased significantly, and companies do not consider it a profitable resource.
The setup of novel green hydrogen projects requires substantial energy and water for electrolysis, creating significant challenges regarding land allocation for green hydrogen production and water availability for other purposes. In regions with insufficient energy infrastructure, poorly planned green hydrogen projects could lead to social inequalities in electricity and water distribution for such projects. Therefore, careful planning and consideration of local socio-economic factors are essential to ensure the sustainable implementation of green hydrogen projects.
Novel Developments and Innovations in Hydrogen Production
Electrolysis techniques produce green hydrogen. However, current electrolysis techniques are inefficient and limited in scalability.
Decoupled water electrolysis (DWE) represents an innovative approach in electrolysis technology where the hydrogen and oxygen evolution reactions (HER and OER) are separated temporally or spatially. This approach has inspired innovative solutions to address the challenges associated with traditional water electrolysis methods.
Researchers from Israel proposed an electrochemical and chemical cycle that involves dividing the OER process into two sub-reactions: electrochemical and chemical steps. This concept, similar to the electrochemical and thermally activated chemical (ETAC) cycle, aims to improve the efficiency and rate of oxygen evolution while maintaining higher efficiency and performance.
In this approach published in Nature Materials, instead of using a nickel (oxy)hydroxide anode, the researchers employed a soluble redox couple (SRC). The SRC facilitates the OER process by supporting continuous operation and enabling a highly efficient isothermal process. By leveraging this innovative approach, researchers aim to overcome the limitations associated with traditional OER processes and advance the development of efficient and sustainable hydrogen production technologies.
The research team showcased remarkable efficiency and productivity within a nearly neutral electrolyte composed of NaBr dissolved in water. In this setup, electro-oxidation of bromide occurred to form bromate alongside hydrogen evolution in one cell, while bromate was chemically reduced to bromide through a catalytic reaction that resulted in oxygen evolution in another cell. Notably, a high faradaic efficiency of 98 ± 2% was attained using a 1.5 M NaBr electrolyte.
Another major development is applying a novel cutting-edge approach to building green hydrogen by the University of Michigan. The new process involves breaking down water using the process of solar water splitting. The main objective of the researchers was to improve the stability of perovskite-based solar cells to make green hydrogen production technology inexpensive and easily accessible.
The solar thermal energy in the water-splitting technique mimics photosynthesis and breaks down hydrogen from water molecules through sunlight. This hydrogen can substitute traditional fossil fuels. By utilizing gallium nitride (GaN), which is often applied in LED lighting and electronics, the team has worked on the surface stabilization of perovskite.
This project is backed by the Department of Energy's Funding from its Energy Earthshots Initiative. The primary purpose of this proposal is to cut the cost of clean hydrogen by 80% and decrease it to a dollar per kilogram in around 10 years.
Like all other technologies, digital tools like artificial intelligence (AI) are optimizing and increasing the efficiency of green hydrogen production. A research team from the National Institute for Materials Science has pioneered an AI technique designed to accelerate the identification of materials possessing desired traits for economical green hydrogen production.
Through this innovative approach, the team successfully uncovered electrolyzer electrode materials that exhibit exceptional performance without relying on platinum-group elements, which were considered necessary in water electrolysis. These breakthrough materials hold significant promise for significantly reducing the costs associated with large-scale production of green hydrogen.
The electrode materials were fabricated using inexpensive and commonly available metals such as iron and zinc. As this project highlights, the implementation of AI will continue to boost the production of green hydrogen in the coming years.
The interest in green hydrogen is also significant from a commercial point of view. Honda recently finalized crucial strategic policies to increase the adoption of hydrogen fuel cell technology as part of its efforts to expand its hydrogen business and achieve its global goal of net zero emissions, including carbon neutrality for all products and corporate activities by 2050.
The company has partnered with General Motors (GM) to manufacture the new generation of Honda fuel cell (FC) systems in Michigan, marking a significant milestone as hydrogen fuel cells are produced at scale for the first time.
For over 30 years, Honda has been researching and developing hydrogen technologies and fuel cell electric vehicles (FCEV), leading the industry by conducting comprehensive real-world testing. The latest Honda fuel cell system represents a significant advancement, enhancing performance and providing a major boost to durability while reducing costs by two-thirds compared to the previous generation system.
The Future of Green Hydrogen in Transportation
Green hydrogen energy is inevitably the future of energy generation. To significantly reduce harmful emissions, major industries, such as manufacturing, transportation, aerospace, and the chemical sector, need to invest in researching and developing a comprehensive framework to integrate green hydrogen as an energy source.
Financial challenges, scalability issues, and storage problems present a significant hurdle. However, governments worldwide must devise and implement concrete policies for renewable energy sources like green hydrogen. It could be our only hope to save the planet and future generations.
Read More: Introducing the Largest Zero-Carbon Green Hydrogen Storage Hub
References and Further Reading
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European Maritime Safety Agency, (2023). Potential of hydrogen as fuel for shipping. [Online] Available at: https://www.emsa.europa.eu/publications/reports/item/5062-potential-of-hydrogen-as-fuel-for-shipping.html [Accessed 24 March 2024].
European Parliament, (2023). Renewable hydrogen: what are the benefits for the EU?. [Online] Available at: https://www.europarl.europa.eu/topics/en/article/20210512STO04004/renewable-hydrogen-what-are-the-benefits-for-the-eu [Accessed 25 March 2024].
Hanway, H., (2023). New method to produce green hydrogen offers promising path to carbon neutrality. [Online] Available at: https://ece.engin.umich.edu/stories/new-method-to-produce-green-hydrogen-offers-promising-path-to-carbon-neutrality [Accessed 26 March 2024].
Honda, (2024). Next-Gen Honda Fuel Cell System Plays Key Role in Hydrogen Business Strategy. [Online] Available at: https://hondanews.com/en-US/releases/next-gen-honda-fuel-cell-system-plays-key-role-in-hydrogen-business-strategy [Accessed 27 March 2024].
National Institute for Materials Science, (2024). AI technique promotes green hydrogen production using more abundant chemical elements. [Online] Available at: https://phys.org/news/2024-03-ai-technique-green-hydrogen-production.html [Accessed 26 March 2024].
Office of Energy Efficiency & Renewable Energy, (2022). Hydrogen’s Role in Transportation. [Online] Available at: https://www.energy.gov/eere/vehicles/articles/hydrogens-role-transportation [Accessed 23 March 2024].
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Atilhan, S. et al. (2021). Green hydrogen as an alternative fuel for the shipping industry. Current Opinion in Chemical Engineering, 31, 100668. Available at: https://doi.org/10.1016/j.coche.2020.100668
RBS International, (2023). Green Hydrogen: The Impact on Transport and Energy. [Online] Available at: https://www.rbsinternational.com/insights/2023/01/green-hydrogen-the-impact-on-transport-and-energy.html [Accessed 25 March 2024].
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