Hydrogen engines: how they work and why they are key to the future

Hydrogen engines remain one of the most promising options for the future of sustainable automotive. Despite some technical and logistical challenges, this technology has sparked growing interest among major brands such as Toyota, BMW, Mazda, Hyundai and Ford, which have already invested significant resources in the development of these systems. Currently, there are two main types of hydrogen engines in the industry: hydrogen internal combustion engines and fuel cell engines.

In this article, we will explain the operation of hydrogen engines, their main characteristics, the advantages and disadvantages of each of the systems, and how they can impact the future of transportation.

How does a hydrogen combustion engine work?

The hydrogen internal combustion engine works very similarly to a traditional gasoline or diesel combustion engine, but with one significant difference: it uses hydrogen as fuel instead of petroleum derivatives. In this case, the hydrogen mixes with oxygen inside the combustion chamber and is ignited by a spark, exactly as in a conventional engine. This process releases energy that drives the pistons and generates mechanical movement.

One of the main advantages of this type of engine is that, instead of producing carbon dioxide (CO2), it emits steam as a by-product. However, due to the high temperatures reached during combustion, nitrogen oxides (NOx) are generated, which are still pollutants. To mitigate this problem, some solutions include the injection of water into the intake system, a technique that has been shown to significantly reduce the formation of NOx.

However, hydrogen combustion engines also face challenges related to the energy density hydrogen, which is lower than that of other liquid fuels. This means that a greater quantity of hydrogen is needed to do the same job as a petrol engine. Although they can run on alternative fuels such as CNG or LPG, storage remains a hurdle as hydrogen must be stored at very high pressures, typically 700 bar, which requires the use of very expensive specialised tanks.

Examples of hydrogen engines

A notable example of a hydrogen engine is the bmw 750hl, which was one of the first vehicles to use liquid hydrogen as fuel. This model required extremely low temperatures (-253ºC) to efficiently store hydrogen in special tanks. Although surpassed by new designs, it represented a milestone in the development of this technology.

Another case is the engine Hydrogen Aquarius, developed by an Israeli company. This engine stands out for not requiring lubricating oil, which simplifies its maintenance. In addition, its innovative system minimizes NOx emissions, and due to its lightness and low cost, it is presented as a viable option for both vehicles and power generators.

How a hydrogen fuel cell engine works

In contrast to combustion engines, combustion engines fuel cell They convert hydrogen into electricity through an electrochemical process called reverse electrolysis. When hydrogen stored in tanks is combined with oxygen in a fuel cell, electricity is generated to power an electric motor, while the only byproduct is pure water.

This process is much more efficient than hydrogen combustion, and, most importantly, it does not emit pollutants. However, the high cost of producing fuel cells is a key obstacle. Currently, platinum is used as a catalyst in the process, but some researchers are looking at more affordable alternatives, such as ferroalloys, to reduce the cost.

A great example of fuel cell technology is the Toyota Mirai, which has attracted attention for its performance and ability to travel up to 650 km on a single charge of hydrogen. This type of technology is ideal for vehicles that travel long distances, such as trucks or buses, due to the greater autonomy they offer compared to conventional electric cars.

Advantages and disadvantages of hydrogen engine

Hydrogen engines, both combustion and fuel cell, offer a range of advantages. and advantages y challenges, which should be considered before widespread adoption:

• Advantages:
• Hydrogen refueling times are significantly shorter (less than 5 minutes) compared to charging electric batteries.
• Emissions are much lower or non-existent, depending on the system used.
• Hydrogen is the most abundant element in the universe, making it a sustainable option in the long term.
• Hydrogen vehicles can purify the air they drive through, like the Hyundai Nexo, which contributes to improving the urban environment.

• Disadvantages:
• The cost of fuel cell production and hydrogen storage infrastructure remains high.
• Hydrogen refueling infrastructure is limited, with few stations in most countries.
• The hydrogen production process is not always clean, especially if it is derived from non-renewable sources.

Autonomy and safety in hydrogen vehicles

Hydrogen vehicles stand out for their autonomy, reaching figures comparable to those of gasoline cars. Models such as the Hyundai Nexo They offer up to 666 km of autonomy, while the Toyota Mirai exceeds 650 km. This makes hydrogen vehicles highly competitive in terms of long-distance mobility.

With regards to security,, hydrogen tanks have been designed to withstand extremely high pressures and even gunshots, as claimed by Toyota in its Mirai model. The infrastructure and safety standards for hydrogen vehicles have advanced greatly in recent years, resulting in vehicles that are as safe as their gasoline or diesel equivalents.

The future of hydrogen in the automotive industry continues to evolve. With the advancement of internal combustion and fuel cell technologies, along with the development of more efficient infrastructure, we are likely to see an increase in the adoption of hydrogen-powered vehicles.