What Are Fuel Cell Stacks?
Fuel cell stacks are the power-generating units of a fuel cell vehicle.
Also known as a fuel cell stack, a fuel cell vehicle is called an FCV (fuel cell vehicle). Energy is mainly radiated using electricity generated when hydrogen and oxygen react to replace water.
As a result, no toxic waste gases are generated, making it one of the decarbonization technologies that has been attracting attention in recent years.
Uses of Fuel Cell Stacks
Fuel cell stacks are used to power fuel cell vehicles. By electrochemically reacting to hydrogen and oxygen in the air, an electrical output is obtained to power the vehicle.
Fuel cell stack-based fuel cell vehicles are in increasing demand due to their strong output and compact size. They are also attracting attention as a decarbonization technology toward achieving carbon neutrality.
It is a key technology for fuel cell vehicles, characterized by high energy conversion efficiency, reduced harmful emissions to the environment, low noise, and fast load response.
Principle of Fuel Cell Stacks
Fuel cell vehicles typically generate electricity with a polymer electrolyte fuel cell (PEFC). Fuel cell stacks play the role of a power generator.
Currently, hydrogen and oxygen are used as fuel cells in many fuel cell vehicles. Hydrogen is supplied to the fuel electrode and oxygen to the air electrode. In the electrolyte sandwiched between the two layers of fuel and air poles, hydrogen ions produced at the fuel electrode move toward the air electrode.
The principle is that the electrons separated at the fuel electrode then move through the electronic circuit, generating an electric current. This principle is commonly used for fuel cell stacks for vehicles, and its advantages include operation at low temperatures and high power generation efficiency, even in a small size.
By incorporating hydrogen and oxygen from the atmosphere into the fuel cell stacks installed in the vehicle, electricity is generated, and the electrical energy is used to drive the battery and motor, thereby powering the vehicle.
Structure of Fuel Cell Stacks
Fuel cell stacks are made by stacking flat cells in a stack structure, and connecting multiple cells in series to obtain the output required for the vehicle. The inside of the cell consists of three layers (fuel electrode, electrolyte, and air electrode), and although a single cell can generate electricity on its own, a number of cells are stacked in a stack structure to produce the voltage required for a fuel cell vehicle.
Since heat is generated during power generation, the stack is cooled to suppress the temperature rise during use.
Characteristics of Fuel Cell Stacks
Fuel cell stacks have several differences from conventional vehicles. They are able to provide a comfortable ride and run on less electricity because they have features that are unique to fuel cell stacks.
Other than that, one of the features is that they can run safely for a long time with a single fill, and many innovations have been made to realize these features.
1. Battery
Electricity generated by fuel cell stacks is either sent directly to the motor or stored in batteries, which are nickel-metal hydride or lithium-ion batteries, similar to electric vehicles and hybrid vehicles, which are vehicles powered by something other than gasoline.
The unique feature of the two types of batteries is that they can supply power directly to the motor, making it possible to use even less battery capacity than in an electric vehicle.
2. Cooling Water
Fuel cell stacks require dedicated cooling water. The main component is an ethylene glycol solution with excellent cooling performance and anti-freeze, and has low conductivity to prevent electric shock.
This feature reduces the risk of ignition or electric shock in the event of an accident and is therefore widely used by various manufacturers. In addition, the coolant used is divided according to the make and model of the car to ensure optimal running.
3. Environmental Friendliness
Since only water is discharged during driving, it helps reduce CO2 emissions. Since no combustion is used to generate electricity, there is no generation of nitrogen oxides.
Fuel cell stacks do not require any gasoline, which is used in many automobiles, and help solve the problem of exhaust emissions. In addition, the high efficiency of power generation allows for longer operation with shorter recharging times.