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The birds and the bees of fuel cells and batteries

Canadian engineer Matthew Klippenstein has worked across the clean technology sector for the better part of two decades, racking up experience with the key technologies that will help drive us to a zero-carbon future: hydrogen and fuel cells, solar panels and wind turbines, and battery electric vehicle infrastructure. In a recent article, he posits that it is a mistake for the energy transition to focus solely on battery-electric technology. In our wide-ranging interview, he outlines the critical role hydrogen will play among the diversity of clean technologies that will replace fossil fuels and take us towards a zero-carbon future.

We have read your article “The Bug in The Battery-Take-All Perspective”. Can you explain the title?

There is a lot of enthusiasm for batteries nowadays, as we have many battery-electric vehicles on the road. This is fantastic because it can help us reduce the amount of pollution and carbon dioxide we are emitting into the atmosphere. But there is a bug in the thinking that batteries will be able to solve all our mobility or our pollution reduction needs. That is where we have an opportunity for hydrogen and fuel cells.

Why does it make sense to compare these technologies to natural creatures?

"There is a kind of handshake or baton passing in nature where we see that interior skeletons or endoskeletons are favorable above a certain size. There is a similar phenomenon in transportation technologies." 

In nature, we find that smaller creatures, such as insects, shrimps, crabs or lobsters, have exoskeletons, or an outer shell, which is perhaps the best option from an evolutionary perspective. The challenge is that exoskeletons do not grow, so it is not a favorable solution for larger creatures. This is where we find endoskeletons, or the vertebrae found in all large creatures that have ever existed, from dinosaurs and whales to horses, dogs, humans and all the way down to hummingbirds. There is a kind of handshake or baton passing in nature where we see that interior skeletons or endoskeletons are favorable above a certain size. There is a similar phenomenon in transportation technologies. Up to a certain point, perhaps for many passenger vehicles and certain urban delivery trucks or bus routes, batteries are a fantastic solution. When you reach larger sizes, as in shipping, air, rail, long-haul freight or buses and even some passenger vehicles, then hydrogen fuel cells have a stronger advantage than battery-electric technology. But it is very complementary. There is a balance between the smaller end where battery solutions work well and the larger end where hydrogen fuel cells work better, with a mix in the middle where we have solutions combining both technologies.

What are the limitations of batteries in this analogy?

Evolution is a problem-solving process, by which life seeks to find the most efficient means of surviving. Just as in nature, certain types of skeletons are better suited to certain size creatures, different mobility solutions are better suited to vehicles of different sizes. Weight and size are the main limitations of batteries. In a passenger vehicle, the amount of energy typically used in daily driving does not require that much battery energy. But as we get into areas like long-haul trucking or rail, the amount of batteries needed to move a much larger vehicle becomes impractical. In this case, hydrogen fuel cell solutions become much more favorable.

Why do you think fuel cells are better suited to larger forms of mobility such as trucking, rail, marine and aviation?

"With long-haul trucking, rail, aviation and shipping, the aim is to move very large objects across large distances. In this case, hydrogen fuel cells tend to make more sense."

With respect to fuel cells, the advantage is that compressed or liquid hydrogen is energy dense, broadly comparable to gasoline in energy density. The analogy in nature is the hippopotamus, whose skeleton is quite heavy. If you were to try to create an exoskeleton strong enough to hold up all that weight, it would be absolutely crippling. It is a matter of weight versus motion. When you get to higher vehicle weights, hydrogen is preferable because it allows you to have more electric mobility per mass. With long-haul trucking, rail, aviation and shipping, the aim is to move very large objects across large distances. In this case, hydrogen fuel cells tend to make more sense because we can store energy much more densely to achieve more forward motion per kilogram than we can with a battery system. This would be a similar thing in nature too - if you have a creature that weighs tons, then the most effective way of moving them is with an endoskeleton.

What about micromobility and passenger vehicles?

One major advantage of hydrogen for passenger vehicles is the speed of refueling, which takes about 5 minutes. In addition, you do not need to build as much fueling infrastructure as you would for battery. Another consideration is that for high usage vehicles where uptime is crucial, such as taxis, emergency vehicles and forklifts, the shorter refueling time offered by hydrogen becomes a decisive factor. Wherever time is involved, ease and speed of refueling become a compelling advantage. If you are running 24/7, then you need the fastest refueling possible. In this case, hydrogen fuel cells offer advantages for vehicles of all sizes.

What is your response to those who think like Elon Musk that “success is simply not possible” for hydrogen fuel cell vehicles because the tech is “mind-bogglingly stupid”?

"Batteries and fuel cells are both on the same team, and the team we are fighting is fossil fuel combustion. Knowing that there is little to be gained by criticizing our teammates."

It’s unwise to think that what works for me is the best choice for other people. I see these technologies as complementary. To say that they are rivals is like saying that exoskeletons and endoskeletons are rivals. They each have their strengths where they are excellent and places where they are less effective, but they each have a role in the diversity of nature. Similarly, we are likely to see a diversity of technologies for electric transportation as well. Remember that batteries and fuel cells are both on the same team, and the team we are fighting is fossil fuel combustion. Anything that gets us further to a path of zero emissions and further away from combustion of fossil fuels is a win. Knowing that we are on the same team, there is little to be gained by criticizing our teammates.

You helped administer EV infrastructure incentives in British Columbia: where does the development of fuel cells and batteries stand in this province of Canada?

"Just as we cannot replace all planes or trains with cars, we will not be able to use batteries in all vehicles. That is why we anticipate a larger flood of hydrogen fuel cell vehicles."

Battery electric is already at massive scale, while hydrogen fuel cells are not there yet. Fuel cells are today where batteries were 10-12 years ago. In British Colombia as elsewhere, we have seen an encouraging wave of electric vehicle adoption, which is great and will lower our emissions. British Columbia has set an ambitious target: by 2025, more than 10% of vehicles sold must be zero-emission, 30% by 2030, and 100% by 2040. Thanks in part to the purchase incentives we have, we have already hit the 10% level in advance. Generally speaking, there is enthusiasm for a green recovery and we expect a lot of support for zero-emission vehicles, whether battery or fuel cell based. Just as we cannot replace all planes or trains with cars, we will not be able to use batteries in all vehicles. That is why we anticipate a larger flood of hydrogen fuel cell vehicles.

Is the cost of electric vehicle charging facilities an obstacle to the transition to battery-electric vehicles in Canada?

To use another analogy, if you think about a stock chart you would like to see, it starts off small when you buy and goes up high when you want to sell. The cost of electric vehicle charging infrastructure roughly follows this in the sense that the first pieces of infrastructure tend to be relatively inexpensive: the electric grid is virtually everywhere and it is not too difficult to add access points to charge vehicles. Challenges come over time as you try to add more and more capacity. You have to upgrade transformers and eventually substations. As you move towards 100%, the cost of upgrades can be huge. This applies particularly to transit and trucking fleets, where the cost of installing charging stations for a small community is quite modest. But if you want to move over 1,000 buses, then the extra cost of completing electric system upgrades and ensuring a backup in case of grid outrage becomes very substantial. 

Is the same true for fuel cell infrastructure?

With hydrogen fuel cells, the per-vehicle infrastructure costs move in the other direction: they start off high and then come down very low. The initial startup costs are high, but if you can get a modest fleet like the Hype taxi fleet in Paris today, then the cost of the station per vehicle decreases dramatically, because it doesn’t cost much more per vehicle to build a larger station if you can divide it over many vehicles. The key for hydrogen fuel cell infrastructure is to reach that initial critical mass of usage so the cost per vehicle declines. Once you reach the critical mass, it becomes much easier to add refueling points than to expand the electric grid to accommodate ever more charging stations. The ability to refuel your hydrogen fuel cell vehicle in your neighborhood is probably the one major step that will unlock more vehicle sales. Many countries have announced plans to deploy hydrogen fuel cell networks. It will take some time, but there will be an adequate network to allow people to choose fuel cell vehicles.

Battery advocates often rail on the low efficiency of hydrogen. What is your point of view on this issue?

"Battery electric fans may focus on efficiency, but the rest of the world does not have the same priorities."

The reality is that no one buys a vehicle based on efficiency. Passenger cars are consumer goods: we buy them because we like the brand or they meet our particular need. If we bought based on efficiency, everyone would buy a small two-seater. Instead, people worldwide prefer to buy larger vehicles, such as pickup trucks here in North America. Battery electric fans may focus on efficiency, but the rest of the world does not have the same priorities. Ultimately, what matters is replacing fossil fuels. To do that, we need as many options as possible. To force everyone to pick your option is counterproductive. I think it’s also a case of tunnel vision. When we want to reduce the amount of CO2 we are emitting into the atmosphere, it’s not just the vehicle’s efficiency that counts, it’s the entire life cycle. We have to factor in emissions during production, use and disposal. Efficiency is a bit of a red herring, in that it is not necessarily the main focus we need to consider. Instead, it’s the life cycle basis that counts.

What role do you think hydrogen can play in the energy transition?

"Einstein said light is both a wave and a particle. Hydrogen is similar in that you can use it as energy vector and also as feedstock."

Hydrogen is absolutely an essential part of the energy solution, just as endoskeletons are an essential part of natural diversity. One part of the solution will come from renewable electricity, while another will come from hydrogen. One of the best things hydrogen can do is replace natural gas for seasonal energy storage. Energy usage spikes during winter, but no battery will ever work if you charge it once in summer and discharge once in winter. Hydrogen’s advantage is that we already use natural gas for this function, with salt caverns for storage and pipelines for transport to keep people warm in the winter. Hydrogen allows us to seasonally shift some of this energy from the summer into the winter by using it like natural gas. There is a tremendous role for hydrogen on the energy side to serve as the other half of the handshake with renewable electricity. In many industrial uses, there is an opportunity for hydrogen to replace fossil fuels in such activities as ammonia manufacturing and steelmaking, where we can use hydrogen in place of coal to reduce the iron. Einstein said light is both a wave and a particle. Hydrogen is similar in that you can use it as energy vector and also as feedstock. It has a wonderful sector coupling potential that will become more important in the next decade.

Just as light is both wave and particle, hydrogen is both fuel and feedstock.

Can the 21st century become the century of decarbonization?

Of course, and it will happen based on the critical mass of political will. Someone once said it’s not a silver bullet, but silver buckshot, meaning that it’s not just one solution that will take us to decarbonization. Including solar panels, batteries, hydrogen, fuel cells, regenerative agriculture, many solutions will come forward to make this a reality. Whereas the late 20th century was a time of procrastination, I’m confident the 21st century will be the era of decarbonization.