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What I’ve Learned About Hydrogen Transport

July 4, 2021

Hydrogen vehicles are one of the gasoline alternatives being touted as future of the transportation. Big carmakers like Toyota, Volkswagen and GM have invested heavily into the technology, sinking down tonnes of R&D and releasing their own brand-new hydrogen vehicles in recent years. Governments like those in California have also been building out a network of Hydrogen fuel stations.

Alongside Hydrogen, there’s another big contender for the title of Future of Transport: lithium-ion battery electric vehicles. For the last few years, I actually thought lithium batteries were the only way to go. This belief was driven by Tesla Motors’ meteoric rise in share price and popularity, as well as some basic facts. But recently, I’ve come to realise that Hydrogen does have its own share merits too. And maybe, just maybe, there’s a future where both can exist together.

 

What the H?

It’s the most abundant element in the universe, but doesn’t usually occur on its own on Earth. Right now, most of the hydrogen in the world is produced via natural gas extraction. But it can also be produced by running electricity through water, a process known as hydrolysis. This means that in the future, we have the option to create it carbon-free, once our grids make the renewable transition.

Hydrogen vehicles are also referred to as Fuel Cell Electric Vehicles (FCEV). They work by combining the hydrogen in the car’s tank with oxygen from the air to produce electricity, with water vapour emitted as a by-product. From here, a FCEV is pretty similar to a lithium-battery powered car: it uses electricity to drive a motor, pushing the car forward.

What’s interesting is that this means that both lithium battery and hydrogen vehicles both get their energy from the same place: electricity input. The difference is in how they store that energy: either by charging a battery, or by filling a tank with hydrogen. There are advantages to each, which we’ll get into below.

 

The Case Against Hydrogen

Elon Musk once laid out the case against hydrogen in very simple terms: efficiency and infrastructure. Although clearly he is pretty biased – he does own an electric car company after all. He’s had plenty of negative things to say about Hydrogen, from “mind-bogglingly stupid”, to calling them “fool cells”.

Looking at the hydrogen economy from an efficiency point of view, it is vastly worse than that of a lithium-battery powered one: only 23% of the energy you put into making hydrogen reaches the vehicle.

Assuming you’re making the Hydrogen using electricity, there are more steps along the way before getting it to your car (compared to batteries), each of them wasting a lot of energy.

It looks something like this:

  1. Generate electricity
  2. Create the hydrogen using hydrolysis
  3. Compressed or liquefy the hydrogen, otherwise it just takes up too much space.
  4. Transport it, either through special pipes, fuel trucks, or both, to petrol stations
  5. Drive your car to the station to fill it up

Every step along this chain uses up a lot of energy, and that’s before it even reaches your car. Oh, and don’t forget that this infrastructure of hydrolysis plants, tanks, pipes, trucks and hydrogen stations will cost trillions of dollars to build.

Let’s compare that with battery electric cars:

  1. Generate electricity. No difference here
  2. Send the electricity down power lines. A lot easier and faster than using pipes and trucks
  3. Plug in your car at home or at a charging station to charge your battery. Much more convenient than having to drive to a hydrogen fuel station

We’ve already got the power lines necessary to deliver it, and the efficiency of delivering the energy is around 76% once you account for transmission, charging and discharging the battery. So for every bit of energy you spend powering a hydrogen vehicle, you can take an equivalent lithium battery powered vehicle more than 3 times the distance. We’ll also need a build a network of charging stations for a battery electric future for those long-distance trips, but these are way way cheaper than building and operating hydrogen-refuelling stations.

So why, if hydrogen FCEV’s suffer more than 3 times the efficiency loss and will require a trillion-dollar network to support, are we even considering them compared to lithium battery vehicles?

 

The Case For Hydrogen

Despite all these drawbacks, Hydrogen has a couple of things going for it: energy density and “refuelling” speed.

Battery electric vehicles have really started taking off in recent years. There’s the popularity of Tesla of course, but as of this writing at least 10 consumer car companies have pledged to only produce battery electric vehicles by 2030. But there’s a reason that it’s only happened for electric sedans, SUVs and sports cars for now.

Bigger vehicles, like trucks, ships and planes, need to carry a lot more weight, for much longer distances than the average family car ride. Sure, you can add more batteries to carry more energy, but that makes the whole vehicle heavier. So you end up having to carry more batteries just to carry those batteries, and so on. Compressed hydrogen has over 150 times the energy density of a lithium-ion battery for every kg. So right now, with our current battery technology, it’s commercially viable for smaller cars and luxury SUVs to be battery electric.

Looking at this graph below, you can see how little a vehicle’s weight changes to add range for battery vs FCEV:

 

There’s also refuelling speed: for a Tesla Model S or X, it can take about 10 hours to give it a full charge. This isn’t really a problem if you’re plugging it in overnight like you would a smartphone. But for aircraft and heavy freight trucks and trains, time is money. Any minute they don’t spend out on the air, road or track means a minute they’re not making money. Sitting around and waiting for a few hours at a time just isn’t acceptable. Even the Superchargers that Tesla offers can charge a vehicle in 1-1.5hours, but that just won’t cut it. Hydrogen vehicles can refuel almost like traditional ones: you pull it into a fuel station and take just a few minutes filling up your tank.

Heavier vehicles like trucks, planes and trains also have more natural and predictable stopping points in which to build fuel stations. Think airports, warehouses and rail yards. This creates more of a natural cap in the amount of infrastructure that we’ll need to build, compared with the task of building a fuel station on every street corner.

 

Everyone’s a Winner

Both technologies achieve something crucial: they allow us to electrify our transport. According to Bill Gates’ book How to Avoid a Climate Disaster, this is absolutely key if we are going to eliminate carbon emissions altogether. The goal is to electrify as many industries as possible, and then turn the electricity grid fully renewable. It won’t be easy or cheap to get there, but the alternative is a devastating climate disaster. So it’s going to be worth whatever it takes.

In the future I hope that our advances in battery technology will lead to batteries that are cheap, charge quickly and are energy-dense enough that they can be used in every form of transport big and small. That way, we can avoid all of the drawbacks of hydrogen and have a much more energy-efficient transport sector. But that’s a future that doesn’t yet exist. And it’s one we don’t have time to wait for.

 

 

References

https://c2e2.unepdtu.org/wp-content/uploads/sites/3/2019/09/analysis-of-hydrogen-fuel-cell-and-battery.pdf

https://arstechnica.com/cars/2021/06/planes-trains-but-not-automobiles-why-gm-is-developing-fuel-cells/

https://www.racv.com.au/royalauto/moving/news-information/car-brands-going-electric.html

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