We take out the lab coat, the flask, the batteries and other elements of the chemistry to talk about the electrolysis, this chemical process in which electrical current is used to break down a substance into its basic components. In a home mode it is very well understood, but if we take it to our automotive world: electrolysis is often related to the generationofhydrogen from water. This hydrogen can be used as fuel in fuel cells to generate electricity and power the car engine, or it can also be stored and used in other ways.
With a theoretical basis told as headlines, we are going to delve into this exciting and chemical topic that is on the table of several manufacturers and that may represent the next step (or reinforcement) to what we know as a zero-emission car. Note, there will be a surprise exam…
Electrolysis process and its components
Electrolysis, as you know, is a key electrochemical process that requires the interaction of three fundamental elements: the electrodeshe electrolyte and the current electrical energy that drives the non-spontaneous reaction. Separately, each element is specialized as follows:
Electrodes: The electrolysis unit comprises two electrodes and an electrolyte, the electrodes being the electric conductors that make contact with the non-metallic portion of a circuit. These elements, known as anode and cathode, facilitate the transfer of ions, thus enabling the chemical reaction. The most advanced students will be able to identify:
- He anode (+) is the electrode that give in electrons, triggering an oxidation reaction. Materials commonly used to make anodes include natural flake graphite composites, mesophase carbon microspheres, and artificial graphite derived from petroleum coke.
- He cathode (-) is the electrode that you accept the electrons coming from the anode, giving rise to a reduction reaction. Cathodes are generally made of various metals, the most common being lithium, iron, aluminum, cobalt and manganese.
For his part, the electrolyte It is any substance that contains free ions, converting the substance into an electrical conductor. This word will sound familiar to you from certain sports drinks and you are not on the wrong track. From a practical point of view, the electrolyte is presented as an aqueous or saline solution in which the electrodes (anode and cathode) are immersed. The combination of these components constitutes the electrolysis cell, allowing the ion transfer between the anode and the cathode when an electric current is applied.
Types of electrolysis
Once the process is understood, let’s now go with the different types that we can find:
Electrolysis of water by electrodes: This method involves the decomposition of water (H₂O) into oxygen (O₂) and hydrogen (H₂) through the use of electric current. The electrodes (anode and cathode) are immersed in water and an electric current is applied. At the anode, oxidation of water occurs, releasing oxygen, while at the cathode, reduction occurs, releasing hydrogen. The overall chemical reaction is: 2H₂O → 2H₂ + O₂.
Alkaline electrolysis: Here, electrolysis is performed in an alkaline solution, usually with sodium hydroxide (NaOH). Here, nickel or steel electrodes coated with catalytic materials are used, and the overall reaction is similar to the electrolysis of water. This approach is often used for industrial hydrogen production.
Proton Exchange Membrane (PEM) Electrolysis: In this type of electrolysis, a proton exchange membrane is used as a separator between the anode and the cathode. The membrane allows protons to move toward the cathode while blocking the passage of electrons, forcing them to follow an external path, thus generating electrical current. This method is commonly associated with fuel cells.
Solid Oxide Electrolysis (SOEC): Electrolysis is carried out at high temperatures using solid oxides as electrolytes. Ionic conductive ceramic materials allow the transfer of oxygen through the cell, where the decomposition of water into oxygen and hydrogen can occur.
Electrolysis of molten salts: Lastly in this method, a molten salt is used as the electrolyte instead of an aqueous solution. The high temperature facilitates the conduction of ions and allows the electrolysis of various substances, including metals.
Electrolysis applied to the automotive sector
Electrolysis, in the context of vehicles, finds applications mainly in the generation of hydrogen as fuel for fuel cells. But we are going to expand this statement and focus the shot on the fuel cells for vehicles (FCV):
Electrolysis is used to produce hydrogen, and this hydrogen can be used in fuel cells installed in vehicles. In a fuel cell vehicle, hydrogen combines with oxygen from the air in the fuel cell to generate electricity and water as byproducts.
The electricity generated powers the vehicle’s electric motor, providing a clean and efficient propulsion alternative.
As we already know, vehicles powered by fuel cells have a series of advantages VS thermal cars. The first thing is that they are cars with zero local emissions since the only direct emission from a fuel cell vehicle is water, which contributes to the reduction of local pollution. On the other hand, we can have greater autonomy, these fuel cell vehicles can offer greater range compared to some battery-based electric vehicles. Finally, in terms of fast recharging, we have to mention that hydrogen recharging can be faster than battery recharging in some cases.
Keys to a future FCV
Like any new technology, we encounter the same initial problems. The first is the charging infrastructure, for the moment (2024), with a very basic network and with an availability of stations lower than those for electric charging. On the other hand, there is conversion efficiency, this means that although fuel cells are efficient, the production of hydrogen through electrolysis can involve energy losses in these initial states, especially if the electricity used does not come from renewable sources. To contextualize, this drawback that lies in the losses during electrolysis It means that the efficiency of the entire energy chain, from electricity generation to vehicle operation, is only half that of a battery electric vehicle (BEV). However, when considering the full life cycle of fuel cell vehicles (FCEVs) and BEVs, the differences are considerably reduced.
On the other hand, the continuous research and developments Several manufacturers are focusing on how to first solve the second of the problems to improve the efficiency of fuel cells and reduce the costs associated with the production and use of hydrogen.
About him environmental impact We have to answer the following question: To what extent is hydrogen propulsion sustainable and environmentally friendly? A desired scenario, from an environmental perspective, would be for a vehicle to run exclusively on renewable energy, without generating harmful emissions. The case of fuel cell vehicles is closer to this precept than other vehicles with other types of propulsion.
Speaking in legal terms, alternative propulsion systems must reduce emissions of pollutants, especially those of CO2 that affect the climate, as well as gases harmful to health, such as nitrogen oxides. Hydrogen vehicles emit only water vapor in their exhaust gases, which means that fuel cell propulsion does not contribute to local emissions, keeping the air in cities clean.
Finally we have to talk about how manufacturers and suppliers manage to protect the climate. In this sense, everything depends on the conditions of hydrogen productionsince manufacturing requires electrical energy to carry out the electrolysis process, breaking down water into hydrogen and oxygen. If the electricity comes from renewable energy sources, hydrogen production leaves no carbon footprint. However, if you use fossil fuelsthe hydrogen vehicle can have a negative impact on the climate, which will vary depending on the “energy mix” used.
Within these “ingenuities” of how to be as efficient as possible we have the factors that directly affect production and its final transportation. Hydrogen can be produced by taking advantage of excess renewable electricity, being a byproduct in industrial processes. Fuel cell propulsion offers opportunities to recycle this hydrogen, especially when it is generated as waste in industrial processes. The production of blue hydrogen, from fossil fuels with carbon capture and storage, is also an option. He transportation and storage of hydrogen affect the energy balance of fuel cell vehicles. Although more complex and energy intensive than gasoline or diesel, hydrogen can be generated locally where there is electricity and water. With more developed infrastructure, transportation routes could be significantly shortened in the future and, therefore, future users of this fuel will see lower costs. reasonable prices in the total count of having an FCV vehicle.