Currently, humanity is increasingly interested in renewable and clean energy sources due to environmental pollution and resource depletion. Among them, hydrogen energy is attracting attention as an eco-friendly alternative energy source, but there are many technical challenges to be solved in hydrogen production, storage, fuel cell technology, etc. for practical use.
Currently, humanity’s main energy sources are hydrocarbons such as coal and oil, and nuclear energy using nuclear fission. Hydrocarbons have the problem of environmental pollution and resource depletion due to the production of carbon dioxide, and nuclear power has the disadvantage of causing massive secondary environmental pollution when facilities are destroyed. These problems with traditional energy sources are among the biggest challenges facing humanity today, making it imperative to find new alternative energy sources that are environmentally and economically sustainable.
In his book The Third Industrial Revolution, world-renowned economist Jeremy Rifkin states that
“Whereas the first and second industrial revolutions relied on fossil fuels such as coal, oil, and natural gas, the third industrial revolution, which is coming and is already underway, is characterized by the use of renewable solar, wind, and geothermal energy to produce and harness clean hydrogen, electrical energy, and more.”
The interest in renewable, clean energy sources is enormous, especially in the face of climate change. In particular, as the international debate on climate change grows, so does the need for global cooperation to reduce carbon emissions. In particular, hydrogen energy, which can produce 2.75 times the energy of gasoline (122 KJ per gram of hydrogen) and does not produce greenhouse gases, has been recognized as a clean energy source. Hydrogen energy can be utilized in many industries, especially in transportation, where it is seen as a key power source for the future. In the field of materials engineering, various research on hydrogen production, storage, etc. is underway, and the development of related technologies will bring tremendous benefits to humanity if an eco-friendly, renewable energy vehicle is created.
Many leading automobile companies are currently working hard to develop hydrogen vehicles to make them practical. There are two types of hydrogen cars: hydrogen engine cars, which use hydrogen directly as fuel for the internal combustion engine, and hydrogen fuel cell cars, which use fuel cells. Fuel cells react hydrogen with oxygen from the air and use the resulting electricity to generate electricity. Hydrogen vehicles have been developed in various directions, and some of them are in the stage of commercialization, so they will surely be the driving force of the hydrogen era. In addition, technological advances in various applications that utilize hydrogen as energy are not limited to hydrogen vehicles, but are expected to have a broad impact on the entire industry.
Let’s take a look at the technological factors that need to be considered for the commercialization of hydrogen vehicles from a materials science perspective.
First, the case of hydrogen-powered vehicles. The fundamental technical problem with hydrogen-powered vehicles is flashback under high load. The phenomenon of backfire is literally the backward flow of flame, and when fuel is burned in an internal combustion engine, backfire occurs from the cylinder to the intake pipe when the ignition timing is inconsistent or the intake valve is opened and closed at the wrong time. Therefore, hydrogen engine vehicles require technology to achieve high power while establishing technology to suppress backfire. Hydrogen is a carbon-free fuel, but when applied to an engine, nitrogen oxides (NOx) are emitted due to incomplete combustion. Unlike hydrogen fuel cells, the emission of NOx is a major factor that reduces the eco-friendliness of hydrogen engine vehicles. Reducing NOx emissions to zero is one of the biggest technical challenges to commercializing hydrogen-powered vehicles.
Also, hydrogen fuel itself is expensive. Currently, hydrogen is mostly produced by separating it from fossil fuels, which is more expensive than conventional petroleum-based fuels. The production of hydrogen by electrolysis of water uses more expensive electricity, so the technology to produce hydrogen in large quantities at low cost needs to be established. For now, it is important to increase the efficiency of the production process and develop alternative technologies to reduce the cost of hydrogen production.
Second, hydrogen fuel cell vehicles. The core part of a hydrogen fuel cell vehicle is the stack, which is a stack of fuel cells stacked on top of each other and is the same part as the engine of a regular car. There are a variety of technical challenges in this area. There are many unresolved issues, such as whether the stack can perform in cold winters, whether the engine will not vibrate too much when starting, whether the electricity supply will be smooth, whether the humidity in the stack will remain constant, and what to do with the unreacted hydrogen that remains after the reaction. In addition, different fuel cell manufacturers have different standards, so there is a need for unified guidelines for practical fuel cells.
Additionally, one of the biggest barriers to commercializing hydrogen fuel cell vehicles is the rising cost of the stack due to the use of expensive precious metals as catalysts, which account for about 77% of the cost of a fuel cell system. Although technological advances in catalysts and separators that can increase the efficiency of fuel cells have led to significant price reductions, the limited reserves of precious metals are not sufficient to replace some of the current internal combustion engine vehicles with hydrogen fuel cell vehicles. Therefore, low-cost catalysts that are stable at low temperatures and can achieve high efficiency must be developed before hydrogen fuel cell vehicles can become practical. This research has the potential to revolutionize not only the automotive industry, but also the global energy market.
A lot of research is being done to harness hydrogen energy as an environmentally friendly renewable energy source. Materials engineering students are working to solve a number of challenges, including how to use electrolysis or water splitting instead of fossil fuels to produce hydrogen, how to store it, and how to control the amount of hydrogen produced. Ultimately, the goal is to develop internal combustion engines for hydrogen-powered vehicles and fuel cells for hydrogen fuel cell vehicles. These technologies are good examples of the need for materials science in the automotive industry to respond to future environmental and energy challenges. In the near future, as long as the technical uncertainties are resolved, we will see hydrogen vehicles driving around us, made possible by the wonderful harmony between the automotive industry and materials science.
The successful commercialization of hydrogen energy will not only provide a new form of transportation, but will also be a major turning point in our contribution to environmental protection and sustainable development. Even now, researchers are actively working in laboratories to improve the efficiency, reliability, and cost of hydrogen fuel, which will play an essential role in solving humanity’s energy challenges.
