Exploring Hydrogen as a Fuel Option

This is a complex subject, but I’m going to try and summarise and then leave links for those that wish to delve into the physics and engineering issues.

Full disclosure, I love the experience of a combustion engine car. I’m a petrol head. But it does not blind me to the environmental challenges we face. I believe in climate change and the net zero goal. So the potential of hydrogen was of great interest to me.

In this article, I want to focus on the role of hydrogen in powering passenger cars only. Heavy vehicles are a different consideration.

For us car owners, I’ve broken this down into 3 main areas of consideration:

1. The challenges of producing and storing hydrogen efficiently.
2. The concept of hydrogen-powered combustion engines.
3. The viability of hydrogen fuel cell vehicles.

For those that just want a quick TLDR:

• Hydrogen production results in a 33%-56% energy loss.
• Hydrogen powered combustion engines cars don't have enough space to store the fuel effectively.
• Hydrogen fuel cell vehicles are less efficient electric cars than their battery powered counter parts.

For those that want the details please read on.

The Challenges of Hydrogen Production

Hydrogen, the most abundant element in the universe, presents a paradox in the quest for clean energy. Despite the amount of it in existence, hydrogen seldom exists in pure form, typically bound to other elements, necessitating energy-intensive processes to isolate it. The only environmentally friendly process to do this is Electrolysis.

However, it's not particularly efficient. Regardless of the source of electricity used to drive the electrolysis (i.e. green or not), production energy loses are about 33% (and can be up to 56% in less ideal conditions).

Energy Losses in Detail:

• Electrolysis: Results in a 20-30% energy loss.
• Storage: Compressing hydrogen for storage accounts for an additional 13% energy loss, while liquefying hydrogen—a method used to reduce storage space—can lead to a 40% loss of generated energy.
• Transportation: Delivering hydrogen to fueling stations introduces further costs, ranging from 10-40%. Although onsite production at fuel stations can mitigate these losses, the majority of hydrogen is produced in large, offsite facilities.

The Bottom Line:

If hydrogen production uses electricity from fossil fuels, it cancels out the environmental gains, making such initiatives self-defeating. Additionally, these energy 'costs' involved in hydrogen production put any dependent technology at an inherent disadvantage.

For those interested in a deeper exploration of hydrogen production's complexities and its environmental implications, this comprehensive YouTube video offers valuable insights:

Watch the video

Hydrogen-Powered Combustion Engines: 

Adapting combustion engines to run on hydrogen instead of gasoline is technically feasible and has been successfully demonstrated, notably by Toyota's Hydrogen-powered Corolla in a 24-hour endurance race. This showcased the potential for hydrogen in traditional engine formats. However, the optimism ends there due to significant challenges.

The Core Issue: Hydrogen Storage and Range

The primary obstacle with hydrogen combustion engines isn't the technology itself but the practicality of fuel storage. To match the range we expect from petrol vehicles, the hydrogen storage requirements become extremely challenging:

• Using conventional fuel tank sizes, a hydrogen car might only achieve a 50-mile range, yes you read that right - only 50 miles with similar sized fuel tanks. A stark comparison to the 300+ miles we're accustomed to with petrol.
• To extend the range to 300 miles, you'd need to sacrifice most of the car's passenger space to accommodate the pressurized hydrogen tank, fundamentally altering the vehicle's design and utility.

Storing hydrogen as a liquid could theoretically increase storage efficiency by 75%, as demonstrated by BMW with a 7 Series prototype. However, this method introduces its own set of problems:

• Cryogenic Storage Issues: Hydrogen must be kept at -253°C and at high pressure, leading to inevitable hydrogen boil-off. Without constant consumption, this precious fuel must be vented after 17 hours to avoid it becoming essentially a bomb. Because of this it would be completely depleted in 10 to 12 days, making it impractical for regular use.

Safety Concerns and Disappointment

Ask yourself this: Are you happy with the idea of commuting in a vehicle carrying highly pressurized or cryogenically stored hydrogen? Look at the fuss that was created by the thought of EV fires from batteries, and those a) were unfounded and b) are literally slow burners. No big instantaneous explosions. Just one instance of a crash where the tank gets damaged and it's all over.

My personal disappointment is profound, as I once saw hydrogen combustion engines as a beacon for the future of sustainable motoring.

For those interested in seeing these challenges depicted visually, I recommend this insightful YouTube video: Watch the video

In summary, while hydrogen combustion engines offer an intriguing glimpse into alternative fuel sources, the reality of their application presents too many hurdles for them to be considered a viable widespread solution.

Exploring Hydrogen Fuel Cell Vehicles

Hydrogen fuel cell vehicles (FCVs) represent a fascinating branch of the electric vehicle family, deriving power from hydrogen fuel cells rather than conventional lithium batteries.

I think it’s important to make this point clear. Fuel cell vehicles are still electric vehicles. The only difference is where the electricity for the motors comes from. A battery or fuel cells.

Storage Space

FCVs require significantly less hydrogen than their combustion engine counterparts, approximately 28% of the amount, making them a viable option without sacrificing vehicle space or range. However, the process isn't without its drawbacks.

The Efficiency Dilemma

Fuel cells generate electricity through a reverse electrolysis process, achieving around 60% efficiency. Adding the energy losses from converting fuel cell energy into motion, overall system efficiency can vary dramatically:

• In the best-case scenario, fuel cell efficiency might reach 32.85%.
• At worst, efficiency drops to 19.16%

In stark contrast, battery electric vehicles (BEVs) boast an efficiency rate of 67%.

Cost Implications in Real Terms

Consider the Toyota Mirai: its fuel tank capacity supports a 300-mile range:

• With hydrogen costing £10-£15 per kilogram, a full tank equates to £56-£84 per 300 miles.
• Comparatively, a Tesla Model 3 can travel the same distance for approximately £22.5, based on average home charging rates – and even less during off-peak hours (circa £6) or with solar power, potentially reducing the cost to near zero.

The Fundamental Issue with Hydrogen FCVs
Hydrogen FCVs face inherent challenges tied to the physics of hydrogen production, storage, and conversion back to electricity. This cycle - from using electricity to produce and store hydrogen, then converting it back to power the vehicle - introduces multiple stages of energy loss, so the process is always going to be fighting efficiency loses.

The Future of Battery Technology
BEVs don't have these additional steps. Electricity goes directly into the battery and then out again. Sure, it's got efficiency loses converting from AC-DC, but these loses are far lower than the Hydrogen step. As battery technology continues to evolve rapidly, the potential for BEVs looks increasingly promising. With advancements expected to accelerate over the next two decades, the efficiency, cost, and performance of BEVs are only set to improve, making them a compelling choice for the future.

In summary, while hydrogen fuel cell vehicles offer an alternative route to electrification, the practical and economic realities present significant challenges. As we look towards a net-zero future, the evolution of battery technology may well offer the most promising path forward.

For an in-depth look into the engineering and physics I recommend this video: Watch the video 

Addressing Misinformation and Understanding Hydrogen's Role

In today's digital age, misinformation spreads rapidly, particularly on social media. A notable myth is the claim that various vehicle manufacturers, including BMW, are abandoning electric vehicles (EVs) in favour of hydrogen. This is unequivocally false. BMW is on the cusp of launching its "Neue Klasse" of EVs, which they clearly state is the future of all BMWs. A testament to its significant investment in battery electric vehicle technology. Discover the Neue Klasse

This begs the question: Why is such misinformation being propagated? It appears designed to sow doubt among consumers, delaying their transition to cleaner technologies. The result? Prolonged reliance on fossil-fuel-powered vehicles, to the detriment of our global climate goals. Who benefits from that?

Hydrogen's Potential Beyond Passenger Cars

However, this discussion shouldn't overshadow hydrogen's viable applications outside the realm of light passenger vehicles. In sectors such as heavy industry, maritime, and aviation, where the spatial demands and refuelling logistics differ significantly from those of passenger cars, hydrogen offers a promising solution. Its potential for quick refuelling and energy density makes it an attractive option for these applications.

For example, it's truly inspiring to see the strides JCB is making in the field of hydrogen power (https://www.jcb.com/en-gb/campaigns/hydrogen). Their innovative efforts, especially as a British company, are a brilliant showcase of pushing the boundaries towards sustainable solutions.

As such, while hydrogen may face challenges in the passenger vehicle market, its role in other areas remains vital. The continued investment in hydrogen technology is not only necessary but welcome, as we pursue a diverse array of solutions in our journey towards a sustainable future.

This article was written by Dan Owen, a proud nerd and enthusiastic petrol head, tragically optimistic home mechanic and co-founder of KnowYourCar.

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