Hydrogen Fuel Cells are key to reach zero emission in heavy duty transportation

My background is quite unique: I had the chance to work on automotive fuel cells research and development, and battery electric buses integration projects. Being exposed to both worlds, I found it interesting how there seems to be a constant battle between hydrogen believers — and hydrogen skeptics (Elon Musk famously spoke to the later).

Through my work experience, I see the immense potentials of both technologies in reducing transportation emissions in North America— though I believe hydrogen fuel cells will become the dominant solution to electrify heavy duty transportation in the next decades.

A common comment we hear in the industry is that hydrogen fuel cells were already believed to be “the next big thing” in transportation 30 years ago but that never panned out to be true. Though I can see where this point is going, it is not hard to notice that the automotive sector has drastically accelerated its transition towards electrification in recent years. Battery propulsion is a winner these days, but we can’t help but notice that hydrogen fuel cell technology is also emerging, especially in trucks and buses. Without this type of societal shift and our growing concerns for the environment, a wide adoption of fuel cells vehicles couldn’t have been achieved a few years ago, let alone 30 years ago !

Hydrogen fuel cells vehicles must be considered for heavy duty transportation by fleet owners, government and cities supporting the transition. Here are some facts supporting this claim.

About compressed hydrogen as a fuel.

Here are some important benefits of using hydrogen as a fuel that will serve as a basis in reading this article:

  • Hydrogen is a high energy carrier
  • Hydrogen can be transported: it doesn’t need to be produced on-site
  • Heavy duty vehicles use compressed hydrogen at 350 bars: this is a standard used between buses and truck manufacturers, which means that the same fuel can serve multiple types of vehicles (a lot like diesel today)
  • It takes about 10 min to refuel a hydrogen fuel cell bus
  • Hydrogen can be produced through electrolysis, which is essentially breaking water atoms into H2 and O. Provided that the electricity supplying the electrolysis comes from a clean source, your emissions are limited.

Heavy duty fuel cell vehicles store enough fuel to meet today’s range requirements.

A fuel cell bus with a typical tank capacity of 50 kg at 350 bar (equivalent to about 1,600 kWh of battery storage), consuming 11.3 kg H2/100 km, (reported for older generations of fuel cells buses) the vehicle range is 565 km. A transit bus travels 43,647 miles per year in the US on average. Assuming it operates 300 days a year, its daily mileage approximates 145 miles or 233 km. A fuel cell bus largely has the capacity to meet this range demand, and beyond.

Comparison of different types of densities for various fuels. Hydrogens in heavy duty powertrains is stored at 350 bar

The figure above shows that compressed hydrogen has a higher gravimetric density than diesel and gasoline fuels, meaning that there is more energy carried per unit of mass.

In cold climates, hydrogen fuel cells powertrains could be used to achieve 100% zero-emissions.

For countries dealing with extremely cold climates, such as Canada in the winter, it is nearly impossible to rely on electric heating alone. Most battery electric buses deployed today use auxiliary diesel heating systems, which can represent up to 30% of daily diesel bus fuel usage and emits CO2, NOx, and other nasty particles. In milder climates, engineers and designers are using heat pump systems to more efficiently heat the bus and keep the temperature at a comfortable level. This is however not achievable in colder climates when -20 C is a norm in the winter.

New generations of fuel cells operate at higher temperatures (80°C or 176°F). Using a typical heat exchanger system, it is possible to recuperate wasted heat and circulated heated fluids throughout the cabin, thus minimizing and potentially suppressing the need for additional diesel heaters on board.

It is simpler to scale up

My day to day work focuses on supporting fleet owners looking to change their existing infrastructure to going fully electric, believe me when I say that electrifying your fleet with battery and charging equipment is a lot of work! You have to rethink your entire garage layout, make sure you have enough space for every charging unit and accompanying charging cabinets, change your labor workflow to accommodate the plug in time, deploy smart charging algorithm to control your fleet and minimize your peak demand and the list goes on. With these layers of complexity comes a high cost and higher risks for screwing up somewhere along the way.

With fuel cell buses, you are cutting all these steps entirely when you want to electrify your fleet as opposed to a few vehicles. All you really need to think about is scaling up your supply, and perhaps add an extra fuel dispenser to your garage. Scaling up your supply implies that you need to think about allocating a high footprint to install new electrolyzers, compressors and dispensers, along with the additional electrical supply equipment (e.g. substations) to deliver the energy you need to the site.

Since the hydrogen fuel can serve a multitude of fleets owners, the cost of scaling up the operations can be shared amongst different parties and doesn’t need to happen at the garage since the fuel can be transported, thus simplifying the operations.

I once went to a conference organized by the CTE (Center for Transportation and the Environment) in which a curve similar to one below was presented to the audience:

Infrastructure redesign compared to the fleet sizes

This is to show that the level of complexity to adopt fuel cell buses drops as more buses are being replaced. If the intention is to replace a few vehicles then you are probably better off sticking to battery electric vehicles. If you want to electrify your entire fleet, however, it is important to consider hydrogen fuel cell as a viable option. You will notice that there is a point where the battery electric and fuel cell bus lines intersect: at this point in time no one can predict the fleet size at which it happens, as it will take a lot more deployments to find out.

To sum up

I have left a few other benefits of adopting fuel cell buses out of this article, but included those I think are the most important. All in all, hydrogen fuel cells should be considered as a viable and even preferred option for long-term heavy duty fleet electrification, as they come with fewer operational challenges, less complexity and as such more redundancy.

Mechanical engineer who wants to help the planet. Vegan & international, living in Montreal. Here are things that matter to me. Je suis française !

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