BBC TopGear
BBC TopGear
Advertisement feature
View the latest news
Future Tech

Hydrogen fuels might have just got a huge leg-up

New tech promises green hydrogen that’s cheaper and more energy efficient to produce

Published: 21 Mar 2022

Australian boffins have apparently figured out the best way to create hydrogen fuel, producing it at 95 per cent efficiency – more than a 25 per cent improvement than any competing method. Best of all, it only requires electricity, water and some serious science.

By now, you may have figured out that we’re talking about electrolysis – splitting water into hydrogen and oxygen with electricity. With current tech, electrolysis generally produces hydrogen at about 75 per cent efficiency. So to create a kilo of pure hydrogen fuel, which holds about 39.4kWh of energy, it takes 52.5kWh. By improving electrolysis efficiency to 95 per cent, that means it’ll only take 41.5kWh to generate a kilo of fuel. That’s a huge improvement over the old method of electrolysis, but also over the fossil-fuel-based hydrogen production methods, which are about 75 per cent efficient at best. And use fossil fuels, which we’re kind of trying to get away from these days.

Advertisement - Page continues below

If this tech works like its creators say it does, that means green hydrogen will be the cheapest and most efficient to produce. And because wind and solar power are now cheaper than fossil fuels (and only extending their lead), that means green hydrogen could soon be better economically as well as environmentally. Not to over-egg things, but this is huge news for billions of people. And yes, we’ll back that statement up before the article’s over.

Hysata, the company behind the new process, says green hydrogen could cost just £1.15 per kilo in a few years. According to the International Energy Agency, the price of hydrogen production based on natural gas, petroleum products or coal was about 50p to £2 per kilo back in 2019. So it’s already in the ballpark on price. But the cost of hydrogen is heavily dependent on the price of gas, petrol and coal. And has anyone else noticed something of a trend there?

So, petrol is ruinously expensive and not long for this world. Fossil-fuel hydrogen is as awful for the environment as you’d imagine from something that starts off as gas, oil or coal – and it’s getting costlier by the minute. Green hydrogen is environmentally friendly, will only get cheaper as green power costs continue to decrease and doesn’t require any extra expense for carbon capture or similar band-aids for bullet wounds. Hydrogen could finally be having its moment. So, does this mean fuel cell vehicles are too?

Well, no. But it’s still great news. Allow us to explain.

Advertisement - Page continues below

Hydrogen as a fuel to power your car, heat your home or cook your dinner... kind of sucks, actually. Electricity is easier and more efficient to transport and uses existing infrastructure to do so. And when you have the energy where you need it, it’s vastly more efficient to retrieve it from a battery than convert it in a fuel cell. But hydrogen is an absolutely essential fuel all the same. More on that in a bit.

Electricity, once generated, travels through existing power lines at about 95 per cent efficiency, thanks to alternating current and the genius of one Nikola Tesla. Charging a lithium ion battery is about 90 per cent efficient, and using the power from that battery in an electric motor is about the same. Assuming a 95 per cent efficient electric motor (permanent magnet-type motors can reach 98 per cent), that means about 73 per cent of the energy from the power station/wind farm/solar array is converted into forward motion, backward motion or indeed tyre smoke. So, that’s the benchmark.

To produce hydrogen fuel requires energy, be that from the electrical grid or directly from fossil fuels. More than 90 per cent of all current hydrogen production – already a £100 billion a year industry – comes from fossil fuels, and the hydrogen generated holds about 75 per cent of the energy needed to produce it. But let’s take the absolute ideal scenario for hydrogen – 95 per cent efficiency to generate, using renewables-based electricity transported at 95 per cent efficiency. That's 90 per cent efficient fuel, right? Er, not quite.

Hydrogen has three times more energy per kilo than petrol, which sounds impressive. But per litre, at atmospheric pressure, it has all the energy of a parent with newborn twins. To use it as fuel, it needs to be compressed to incredible pressure (generally 5,000 to 10,000 PSI) or kept as a liquid – which means cooling it to less than -253ºC, or just 20 degrees above absolute zero. As you might imagine, it takes some pretty specialist equipment to compress or cool it that much, and then contain it thereafter. And, of course, more energy. In fact, a study by the European Federation for Transport and Environment found that storing hydrogen requires the equivalent of 40 per cent of the energy stored in the fuel itself. So, 90 per cent efficient to make, 54 per cent efficient by the time it’s in your tank – without even taking into account the energy needed to transport it.

Top Gear

Get all the latest news, reviews and exclusives, direct to your inbox.

And then, as you might expect in a fuel-cell vehicle, it’s fed into the fuel cell. The most efficient fuel cells convert hydrogen into electricity (i.e. what we started with) at 60 per cent efficiency. So by the time it reaches the electric motor, you’ve got less than 33 per cent of the energy you started with. Put it through the same 95 per cent efficient motor and just 30.7 per cent of the power you started with is actually making it to the road. And that might not even be enough for tyre smoke.

So, hydrogen's pretty rubbish as a fuel for our machines. But you might remember we said it was a vital fuel all the same. Because, if you’ve eaten at some point today, chances are that it’s thanks to hydrogen production.

Synthetic fertiliser is responsible for feeding “48 per cent of the global population", according to research published in Our World in Data, and “since the share supported by the process continues to rise, this may in fact be a conservative estimate". In case the ramifications aren’t crystal clear, the article goes on to mention that “in 2015, nitrogen fertilisers supported 3.5 billion people that otherwise would have died".

Hydrogen is an essential building block of synthetic fertiliser, which takes nitrogen out of the air and combines it with pure hydrogen to make ammonia, the key ingredient. This increases farming yields and, for about one out of every two people reading this sentence, is the reason you’re not currently starving. And to create this literally life-saving commodity without destroying the planet in the process does feel like it’s something of a worthwhile project, no?

So while hydrogen still loses out to electricity as a fuel for transportation, heating, cooking, powering your laptop and roughly everything else, it’s still an essential fuel for one very good reason. Or indeed 3.5 billion and counting. 

More from Top Gear

See more on Future Tech

Subscribe to the Top Gear Newsletter

Get all the latest news, reviews and exclusives, direct to your inbox.

By clicking subscribe, you agree to receive news, promotions and offers by email from Top Gear and BBC Studios. Your information will be used in accordance with our privacy policy.

BBC TopGear

Try BBC Top Gear Magazine