Can Compressed Hydrogen Gas Power an Internal Combustion Engine?

Hydrogen has been touted as a potential fuel for the future due to its environmental benefits, but its practicality for powering internal combustion engines (ICEs) is often debated. This article explores the feasibility of using compressed hydrogen as a fuel in ICEs, drawing on insights from industrial experience and the latest automotive technologies.

From Electrolysis to Direct Usage

The concept of using hydrogen produced through electrolysis to power cars isn't new. One car enthusiast reportedly set up an electrolysis system with a 12V battery to generate hydrogen gases. Theoretically, this hydrogen could then be used to power an engine. However, this approach faces significant technical challenges.

Industrial Perspective

From my experience in working with compressed hydrogen in a synthetic ammonia plant, hydrogen presents unique challenges. It requires extreme cold storage to remain stable, and it can make metals brittle and cause leaks. Furthermore, compared to gasoline, hydrogen stores far less energy by weight, making it less practical for everyday use.

Engineering Challenges

Hydrogen poses specific challenges for the design and operation of internal combustion engines. Hydrogen molecules are incredibly small and difficult to seal properly, which can lead to leaks. Additionally, hydrogen can embrittle high-strength steel, reducing the lifespan and durability of components. Perhaps the most daunting challenge is the high energy density required for practical storage. Compressing hydrogen to a useful level requires very heavy tanks and fuel systems, which adds significant weight to the vehicle.

Current Research

Despite these challenges, some companies have attempted to develop hydrogen-powered piston engines. One company started to explore the concept with promising results. They used metallic fillers and bonded hydrogen molecules to a matrix to enhance storage efficiency. Some of these issues have been addressed on spacecraft, where the development of appropriate systems was supported by substantial funding.

The Hydrogen Fuel Cell Alternative

One viable alternative to the direct use of compressed hydrogen in internal combustion engines is the hydrogen fuel cell. Fuel cells convert hydrogen and oxygen into water and electricity, producing power without combustion. Toyota, for example, has developed the Mirai, a fuel cell electric vehicle, which is commercially available.

Comparative Analysis

While using a fuel cell presents more efficient power generation, it comes with its own set of challenges. Fuel cell vehicles are currently expensive to run, with high-pressure systems and specialized safety requirements. The infrastructure for hydrogen refueling is still in its infancy, requiring significant investment to become widespread. Additionally, hydrogen is not available naturally, and the energy required to produce it (electrolysis) far exceeds the energy it can deliver, making it an inefficient method of energy storage. The round trip efficiency is typically around 15%, with the average being even lower.

Electric Vehicle Alternatives

For consumers, purchasing a hydrogen fuel cell vehicle or converting a conventional vehicle to hydrogen is not practical. Instead, fully electric vehicles (EVs) with battery storage offer a cleaner, more efficient, and more cost-effective solution. Electric vehicles boast a round trip efficiency of around 90%, and the technology is rapidly advancing. Recent developments in battery storage, such as those by Toyota, have made electric vehicles a more viable and practical option.

Conclusion

While the use of compressed hydrogen gas in internal combustion engines is theoretically possible, the current technological and economic challenges make it impractical for widespread adoption. The advancements in hydrogen fuel cells and electric vehicles point towards more viable solutions for the future of clean energy transportation. As infrastructure and technology continue to evolve, the automotive industry will likely see significant changes in the coming decades.