To meet the target set by the Paris Climate Agreement of limiting global temperature rise to 1.5 °C, researchers have estimated that investments into transitioning from fossil fuels to renewable energy sources will need to increase by 30% by the year 2050. This investment of approximately $131 trillion USD is expected to yield a cumulative payback of at least $61 trillion by the target’s deadline.
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The Growing Need for Hydrogen Energy
About 65% of the global energy demand is met by liquid and gaseous fossil fuels, with petroleum oil being the largest primary fuel source that powers more than 92% of the global transport energy demand.
As the number of automobiles on the roads continues to rise exponentially each year, environmental concerns about exhaust emissions and global warming have also risen. To date, automobiles account for approximately18% of primary energy use and more than 17% of the global carbon dioxide (CO2) emissions. Since CO2 emissions are directly linked with rising water temperatures, there is an urgent need to transition vehicles to cleaner energy sources.
Advantages of Hydrogen Fuel
While several alternative fuel sources have been proposed, hydrogen energy is a particularly promising option because of its ability to reduce greenhouse gas (GHG) emissions and local air pollution.
As a secondary energy carrier, hydrogen energy can be produced from any primary energy source ranging from fossil fuels to nuclear or renewable energy sources.
Several different production methods can be employed to produce hydrogen energy, the most common of which includes the thermochemical process of steam reforming natural gas.
The production of hydrogen energy emits almost no other byproduct, aside from water. This light, colorless, odorless, and non-toxic gas has the highest specific energy content as compared with any other conventional fuel currently available on the market. More specifically, hydrogen has an energy yield of 120 MJ/kg, which is approximately 2.75 times greater than that of hydrocarbon fuels. As a result of this property, hydrogen has a much greater calorific value as compared with gasoline.
Since hydrogen can be safely dispersed within the air, it offers several safety advantages. Hydrogen is a highly versatile element and can easily converted into other forms of energy through various methods such as steam, heat, or electricity.
Current Developments in Hydrogen Vehicles
Hydrogen has had a minimal presence in the global transportation sector. As of 2017, around 8,000 hydrogen fuel cell vehicles were in use worldwide, with the United States and Japan accounting for 90% of these vehicles that were being serviced by approximately 280 refueling stations. However, more recently, several major motor vehicle companies, including Honda, Hyundai, Mercedes, and Toyota have developed hydrogen fuel cell electric vehicles (FCEVs) for purchase.
Aside from passenger transport vehicles, hydrogen energy has become an increasingly popular fuel option for various demonstration projects. To this end, it is estimated that around 25,000 hydrogen fuel cell forklifts are already in use worldwide.
The number of fuel cell buses is also expected to rise globally, with more than 10 companies stating that they will be producing fuel cell buses in the near future. Over 500 buses, 400 trucks, and 100 vans that are powered by hydrogen in combination with fuel cells are already in use around the world.
Future Developments in Hydrogen Transport
Although current developments in hydrogen fuel-powered vehicles are promising, they remain low when considering the overall size of the global transportation market. However, plans to increase the global production of FCEVs are expected to begin in several countries.
Japan is looking to increase the number of FCEVs on its roads to 800,000 by the year 2030. It will accompany this growing fleet of vehicles with the installation of 320 fueling stations by the year 2030. Even more ambitious plans have been announced by China to expand their FCEV fleet to one million by 2030, whereas South Korea is hoping to have 100,000 and 630,000 FCEVs in operation by 2025 and 2030, respectively.
Challenges to Hydrogen-Fueled Transportation
To achieve these goals, one essential aspect of hydrogen-fueled transportation vehicles is the need to provide the necessary infrastructure that will allow hydrogen energy to be delivered to refueling stations efficiently.
The three different options available for hydrogen-delivery pathways currently include compressed tube trailers, cryogenic liquid trucks, and compressed gas lines.
Another major challenge that must be addressed to achieve a hydrogen economy is developing efficient onboard storage systems for hydrogen energy in automobiles. Since hydrogen is associated with a very low gravimetric density, a hydrogen-powered vehicle will require a storage device that is approximately four times greater than that of gasoline to store the same energy.
Several different storage routes have been explored to resolve this issue, including compressed gas, cryogenic tanks, metal hybrids, and carbon nanotubes, to name a few. Further research is still needed to reach an economical and efficient storage solution for hydrogen energy in vehicles.
References and Further Reading
Climate Action Fast Facts [Online]. Available from: https://www.un.org/en/climatechange/science/key-findings.
Singh, S., Jain, S., Vankateswaran, P. S., et al. (2015). Hydrogen: A sustainable fuel for future of the transport sector. Renewable and Sustainable Energy Reviews 51; 632-633. doi:10.1016/j.resr.2015.06.040.
Ahmed, A., Al-Amin, A. Q., Ambrose, A. F., & Saidur, R. (2016). Hydrogen fuel and transport system: A sustainable and environmental future. International Journal of Hydrogen Energy 41(3); 1369-1380. doi:10.1016/j.ijhydene.2015.11.084.
Moriarty, P., & Honnery, D. (2019). Prospects for hydrogen as a transport fuel. International Journal of Hydrogen Energy 44(31); 16029-16037. doi:10.1016/j.ijhydene.2019.04.278.
Ajanovic, A., & Haas, R. (2021). Prospects and impediments for hydrogen and fuel cell vehicles in the transport sector. International Journal of Hydrogen Energy 46(16); 10049-10058. doi:10.1016/j.ijhydene.2020.03.122.
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