Why Hydrogen is Used in Engines Instead of Oxygen

Hundreds of years of industrial and technological advancement have led to society utilizing various fuels and oxidizers in engines. One significant debate is why hydrogen is used as a fuel in some engines instead of oxygen. Let's delve deeper into this topic.

The Role of Oxygen in Combustion

Oxygen plays a crucial role as an oxidizer in the combustion process. When there is the presence of oxygen, the reaction occurs, and this combustion process is what causes the release of heat. Combustion involves the oxidation of fuel by the oxidizer, which, in most cases, is oxygen. This is the primary mechanism through which engines and rockets generate thrust and power.

Combustion and Hydrogen

Hydrogen combustion can yield a small amount of nitrogen oxides along with water vapor. However, the release of energy from this combustion is significant and makes hydrogen an attractive fuel option. In engines, hydrogen is often combined with liquid oxygen to enhance its combustion process.

Engines and Their Oxidizers

Many engines, including auto rockets and liquid hydrogen fuel engines, require both hydrogen as a fuel and liquid oxygen as an oxidizer. Without this dual combination, the engine cannot operate efficiently. Jet engines, however, take oxygen directly from the air, demonstrating that not all engines need both components.

The Hydrogen Fuel Cell

A hydrogen fuel cell is not a standalone fuel source but rather a part of a broader energy conversion process. It is one side of the equation, with oxygen as the other component, usually sourced from the air. The energy released by the reaction between hydrogen and oxygen is used to power automobiles, demonstrating how hydrogen functions as a fuel.

Hydrogen in Fuel Cells

The high calorific value of hydrogen contributes to its preference in fuel cells. It outperforms all other elements available on Earth. While the desire for hydrogen fuel cells is high, there are some challenges, including the longer startup time of solid-oxide fuel cells (SOFC). The relative simplicity of hydrogen fuel cells makes them an attractive alternative.

Conclusion

In summary, while oxygen is crucial as an oxidizer in the combustion process, hydrogen is used as a fuel in engines because of its ability to efficiently release energy, making it an ideal choice for various energy applications. The combination of hydrogen and oxygen creates a powerful and clean energy process that is setting the stage for future advancements in technology and sustainability.