Hydrogen will play a big role in the decarbonization of the transport industry, but will it come in the form of fuel cells, or internal combustion engines or both?

While fuel cells get most of the attention, the fuel can also be used to power trucks with internal combustion engines. Recently, Westport Fuel Systems and Volvo Group formed a joint venture to expand the availability of hydrogen high-pressure direct injection – or HPDI – fuel systems.

Testing has shown that directly injecting hydrogen in an internal combustion engine can bring certain advantages over fuel cells. For more, we sat down with Scott Baker, VP, product development and technology officer with the new Westport/Volvo joint venture.

Scott Baker: First ofall, I want to start by saying and acknowledging that we absolutely expect that fuel cells will be a key part of the decarbonization strategy.

Volvo, as a as an equity investor in the new joint venture, is also an equity investor in cellcentric. So, Volvo has been very public about having a three-pronged approach to their decarbonization strategy: battery-electric vehicles, fuel-cell-electric vehicles and internal combustion zero-carbon fuels.

This new HPDI technology joint venture very much fits in the zero-carbon internal combustion strategy. So, we see them as complementary technologies. So, but getting to the inherent comparison between the two from a thermal efficiency perspective or a fuel economy perspective, although there’s a lot of discussion around fuel cells being extremely high efficiency, when you really look at heavy-duty applications, and the full fuel system or fuel cell system, not just the fuel cell stack, the data that we’re seeing publicly suggests that on a thermal efficiency, basis and energy-to-work conversion basis, fuel cell trucks achieve about a 50 to 55% thermal efficiency in a heavy-duty application.

HPDI hydrogen, I mentioned that using hydrogen with the HPDI technology allows us to actually achieve better thermal efficiency than the base diesel engine. We’re on par, we’re in the low 50% peak thermal efficiency.

The really interesting comparison is that fuel cells are most efficient at low load and engines are more efficient under load. So, at the high load factor applications indicative of heavy-duty truck applications, we see the hydrogen HPDI-powered engines and fuel cell powered trucks having similar energy efficiency.

Lars Stenqvist is chief technology officer with Volvo Group. The company plans to use both fuel cells, and internal combustion engines fueled by hydrogen. I asked Lars how Volvo will determine which solution is the best fit for a given region or application.

Lars Stenqvist: A few years ago, when I got those kinds of questions, I was firm in my own opinion that application A would have Technology X, etc.

Today, I’m more humbled, because this will not only be decided by my engineers, it will very much be decided by the availability of energy, pricing of energy in different regions of the world. So, I think that we can look forward to a situation where you have the same kind of transport application in one region. There you will prefer battery-electric vehicles. In another region you receive fuel-cell-electric vehicles, and in the third region, you will see combustion and consumption of fossil-free fuels like hydrogen.