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Why batteries and hydrogen are not competitors on the road to decarbonized transport

autonomous car
(Image credit: Image source: Shutterstock/LifetimeStock)

For decades, electric vehicles (EVs) have been the subject of intense discussion and development. After many attempts to launch them into the consumer market and much debate about whether they will ever displace conventionally-powered vehicles as the main mode of powering transportation, most of us are familiar with the idea of a battery-powered car. Very recently, however, we have seen a sudden surge in interest around EVs. Technological development has mitigated issues around range and charging speed for batteries, government policy and the economies of scale have brought the price to a level where EVs are accessible to many more people, and – perhaps most importantly – public attitudes are shifting towards seeing the benefits of EVs in light of the intensifying need to decarbonize all parts of the economy.

This year, of course, has been an economic shock for all industries, so it’s remarkable that sales of EVs have been very resilient. In the United Kingdom, for example, the latest year-to-date sales figures from the Society of Motor Manufacturers and Traders suggest that while sales of diesel and petrol vehicles are both down by over 50 per cent compared to 2019, sales of battery electric vehicles are actually up by more than 130 per cent. This is just the latest indication that what was once a niche area of the industry has now been anointed as its future. As EVs become mainstream, we are also seeing a new wave of innovations – with vehicles more connected than ever, incorporating new reporting and networking capabilities that promise to change how we use the roads.

The different types of EV

In the current conversation around zero-emissions vehicles, however, two key considerations are too often missed. First is the fact that, for many people, the term “EV” is taken to mean exclusively vehicles which are powered by on-board batteries – sometimes with qualifying terms like battery electric vehicle (BEV), to designate vehicles powered solely by battery power, and hybrid electric vehicle (HEV), to designate vehicles which have both batteries and internal combustion engines. However, vehicles powered by hydrogen fuel cells have more in common with BEVs than many realize – and are, certainly, just as electric as their battery-based counterparts.

To see why, we need a little bit of electrochemistry. In a modern car battery, you’ll find two electrodes separated by a fluid called an electrolyte and a barrier material which electrons cannot pass through. When the battery is discharging, lithium ions move from one electrode to the other, through the barrier material. To join the positively-charged lithium ions, the electrons which were attached to those lithium atoms have to take the long route around – that is, out through a circuit which passes through the motors and other machinery, where the energy of the electrons’ movement powers the car, and back into the battery on the other side of the barrier.

In a hydrogen-powered car, the fuel cell behaves in a very similar way: hydrogen pumped into one side of the cell from a small tank crosses a proton-exchange membrane impermeable to electrons in order to react with oxygen on the other side, leaving the electrons to take a longer path, powering the car, and completing the reaction when they return to the fuel cell, producing water which is then discharged from the cell.

While the chemical reactions involved are different, the mode of operation is similar enough that we can foresee a future involving vehicles which have been designed to accommodate either type of power, with systems swapped over in much the way you might replace a car’s internal combustion engine today.

Multiple paths towards a shared goal

Recognizing that hydrogen-powered fuel cell electric vehicles (FCEVs) are part of the family, so to speak, with BEVs, we need to start asking not just whether an electric vehicle is the right choice in any given circumstance, but what kind of electric vehicle will fulfill a given function. The second common misconception in the EV conversation, then, is that hydrogen and batteries are competing, alternative visions for the future of mobility. In fact, they are complementary solutions that we need to pursue alongside one another if we are to successfully decarbonize our transport networks – just as, in the past, we have chosen between petrol and diesel vehicles on a case-by-case basis.

For many applications, BEVs are emerging as a clear best fit, as they often need a relatively light rollout of additional infrastructure, they fulfill the power and range needs for a lot of use cases, and, in the passenger car and light-duty van segments, the industry now offers a comprehensive range of vehicle options. Batteries are, however, relatively big and heavy per unit of power storage compared to fuels like hydrogen and hydrocarbons. This means that when it comes to heavy goods vehicles, trains, and other large vehicles, batteries start to add too much weight and take up too much space for the vehicle to be a like-for-like replacement for existing options.

Hydrogen, meanwhile, is the lightest element in the universe, and when compressed into tanks provides the kind of energy density that these vehicles need. Where those vehicles are also based in depots where refueling infrastructure can be provided, we are already seeing real-world use cases demonstrating hydrogen’s value to the mobility network: in Germany, Alstom’s Coradia iLint hydrogen powered train is in commercial service, while for the upcoming 2022 Winter Olympics buses powered by Cummins fuel cells will ferry athletes and visitors between venues.

While currently, BEVs start to fill people’s driveways and complete last-mile deliveries for online shopping, we might see the heaviest vehicles powered by the lightest element. There is plenty of work to do in building the hydrogen economy and demonstrating FCEVs for different use cases – but it’s now clear that hydrogen will play a significant role in our long-term push towards decarbonization. A diverse, clean, connected future for power is within our sights.

Amy Adams, VP of fuel cell and hydrogen technologies, Cummins