From “sun to wheel”, the new energy ecosystem

“Why are you investing in hydrogen-powered drives? It’s a waste, hydrogen is too energy inefficient, especially compared to batteries!”

Although most people share our view by now that hydrogen-based and battery-electric drives are complementary and that both are needed to decarbonise transportation, I still hear statements like this very often.

And yes, it’s true: Compared to a battery-electric truck, a smaller amount of the electric energy coming from a solar panel can be actually used for propelling a hydrogen truck. The ratio is about 70 percent vs. 30 percent. Why? Because a portion of the usable energy is lost when hydrogen is generated in the electrolyzer and later converted into electricity in a fuel cell or burned in a hydrogen combustion engine (H2 ICE). Thus, the so-called “well-to-wheel” efficiency of batteries is better.

But that is just one puzzle piece of a much bigger picture – let’s zoom out:

Firstly, a prerequisite of my thoughts is that we are targeting a decarbonised world. And we know that we have a surplus of green energy on this planet, fortunately more than enough for all, yet like fossils not evenly distributed at competitive cost. Hence, a green world will see massive trade with green energy. Electricity in grids, and molecules to store (if it’s too far away or the energy source is too cyclic).

The decisive question is: Where does the solar energy come from? The solar energy used to charge a battery truck in Europe must also be mainly harvested in Europe, since it needs to be transmitted via the electricity grid.

In contrast: The solar energy used to generate hydrogen for a hydrogen-powered truck can be harvested in much sunnier regions of the world, since hydrogen can be stored and transported globally. There, each solar panel can deliver up to 2 to 2.5 times as much electricity as in Europe.

This means:

• The higher efficiency of solar panels in sunny regions can compensate for the lower efficiency due to electrolysis and drive train conversion [I’ve already acknowledged].
• With a solar installation in the sunny south, a hydrogen truck can drive a similar range per hour of sunshine as a battery truck with energy coming from a solar installation of the same size in Europe.
• We see a balanced “sun-to-wheel” efficiency for hydrogen trucks and battery trucks.

And even if this would not be the case - today, these rays of sunshine mostly hit sand and rocks. Not using this energy from sun on sand, due to a lack of local need or the lack of potential to transport it to other places on this planet, means the efficiency is zero (assuming nobody needs hot sand!).

Talking about waste: not making use of all this potential energy is a real waste in my view.

Therefore: Let’s please stop debating just this one puzzle piece called energy efficiency! Let’s focus on the complete puzzle instead, which is decarbonizing transportation with solutions that work best for our customers – and that’s a combination of hydrogen-powered and battery-electric drives, as both can be the best solution depending on the transportation task.

Special thanks to the team at Mercedes-Benz Trucks UK for permission to run this commentary, a topic we’ll no doubt be returning to on a regular basis…