Hydrogen combustion engines: what are the advantages?

Scientists have tried to find different alternatives to traditional fuels used in engines. Hydrogen is one of those options.

Let’s start with the basics: a car needs energy to move. Now the traditional source has been gasoline. But the need for more sustainable energy sources has led to the discovery of new alternatives. One of these potential replacements is the hydrogen combustion engine, where the main energy source is hydrogen. The question on the minds of experts is: will hydrogen combustion engines ever become viable enough for mainstream use?


What are hydrogen combustion engines?

Hydrogen combustion engines are primarily traditional combustion engines that have been designed to run on hydrogen instead of gasoline.

Advantages of hydrogen combustion engines

There are various advantages that seem to argue in favor of hydrogen combustion engines:

  • The exhaust gases mainly comprise water vapour. This is the main reason why hydrogen combustion engines are preferred. Occasionally there may be carbon dioxide coming out as a residue.
  • The thermal efficiency of these engines (about 45%) is much higher than that of petrol (25-30%) and diesel (30-38%) engines.
  • Those engines that meet strict emissions laws may have negligible NOx emissions.

photo credit: pixabay.com

Why aren’t these viable to use yet?

There are several challenges that the industry still needs to overcome when it comes to hydrogen combustion engines:

  • A large storage space is required for hydrogen tanks, which significantly increases the weight of the vehicle and increases the risk of wear.
  • Since the energy density is so much less, the overall power and torque generated by these engines is much lower than that of traditional combustion engines.
  • The compression ratio of 40:1 is required, which is extremely harsh (petrol only needs 8:1).
  • Since fuel burns so easily, pre-ignition and knocking are major hazards for several engine parts. The engine also often tends to backfire!
  • Even though hydrogen was chosen for its lower emissions, it leaves a higher carbon footprint than traditional fuels which defeats the main purpose of this combustion engine.
  • Mass production of hydrogen combustion engines is expensive!

photo credit: pixabay.com


It’s pretty clear that the disadvantages or challenges of hydrogen combustion engines outweigh the advantages. This raises the question of whether these motors are worth it. It seems highly unlikely that these engines will ever be used en masse. But alternatives to hydrogen combustion engines, namely hydrogen fuel cells, can be a stepping stone to full vehicle electrification. Hydrogen fuel cells are much more compact and easier to produce while causing the lowest emissions. The researchers’ ultimate goal is to produce zero-emission vehicles capable of delivering optimum performance on zero-emission fuels. Torque vectoring is being actively developed alongside hydrogen engines to increase EV efficiency!

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