I often hear people talking about hydrogen as if it’s an either/or choice.
For example, which low-carbon vehicle technology will eventually win out – hydrogen fuel cells or electric batteries.
Elon Musk certainly thinks it will be the latter.
The Tesla founder has gone on record calling hydrogen fuel cells “incredibly dumb” and “mindboggling stupid”. He points to hydrogen being a far less efficient way of producing energy than simply using electricity to charge batteries (and he does have a point, of which more below).
Japan’s hydrogen future
Yet Japan disagrees and is investing heavily in hydrogen as a key national fuel source. By March 2021, it’s aiming to have 160 hydrogen stations and 40,000 fuel cell vehicles (FCVs) on its roads, increasing to 900 stations and 800,000 FCVs by 2030.
But unlike a VHS versus Betamax scenario, many argue hydrogen has an important role to play alongside other low-carbon solutions.
As the most abundant element in the universe, hydrogen produces zero emissions when used for energy – and can be used in multiple ways.
It can be used as a gas, in the same way as natural gas. So hydrogen can heat our homes or provide a fuel source for cooking.
Renewable storage vehicle
And it can act as an energy ‘carrier’ by utilising renewable power for generation (e.g. during times of abundant wind or sunshine), which can then be stored and converted into electricity as required.
Compressed hydrogen has specific energy of 40,000 watt hours per kilogram. Lithium-ion batteries, on the other hand, only have specific energy of 278 watt hours per kilogram at best – with most achieving around 167 wh/kg.
That’s why when it comes to transport, hydrogen in an ideal choice for long-distance and public routes, as it provides far greater range than a battery.
It’s far lighter too, so doesn’t add the same weight that ever-bigger batteries do – which impedes their suitability for heavy goods vehicles or aircraft travel.
Ideal petrol replacement
Hydrogen also better lends itself as a replacement fuel for the UK’s current petrol station network, which is designed for fast turnover ‘fuel and go’ rather than ‘sit and charge’ use.
That doesn’t mean that electric vehicles don’t make sense for low-mileage and urban travel (as long as there’s an accessible charging infrastructure).
So rather than one or the other, one could argue that it makes better sense for both technologies to have a place as we transition to low-carbon transport.
Poor production efficiency
The sticking point with hydrogen is making it is an energy-intensive process.
Steam reforming is the most common industrial method of hydrogen production. This combines high temperature steam with natural gas to extract hydrogen. But the end product generates less energy than the natural gas used to manufacture it.
As well as being used for hydrogen manufacture, natural gas – along with coal – is currently the main source of power used in generating hydrogen.
According to the International Energy Agency, global hydrogen production is responsible for 830 million tonnes of CO2 emissions per year. That’s the equivalent of the annual carbon emissions of the UK and Indonesia combined.
Tapping into renewable sources
Electrolysis is another method of hydrogen production, using power to split water molecules to isolate the hydrogen (and oxygen) atoms.
The electricity for this process can be provided by renewable sources. But it’s estimated that the power lost in production is around 30%, so the hydrogen produced is only 70% energy efficient.
Another method of hydrogen production is polymer exchange membrane electrolysis, which is 80% efficient – and expected to have the potential to increase to around 86% in time. The other benefit of this system is that it can be produced on site, which saves on transport costs/emissions.
But once produced, as hydrogen is a low-density gas, it then needs to be compressed or converted to liquid for storage – which is another energy-intensive process.
Less efficient than batteries
So overall, hydrogen’s energy efficiency is currently far lower than batteries (which are around 98% when new).
But it’s hoped with the right investment and political will, more efficient ways of producing, storing and transporting hydrogen will emerge.
“Hydrogen is today enjoying unprecedented momentum, driven by governments that both import and export energy, as well as the renewables industry, electricity and gas utilities, automakers, oil and gas companies, major technology firms and big cities,” says Dr Fatih Birol, Executive Director of the International Energy Association (IEA).
“The world should not miss this unique chance to make hydrogen an important part of our clean and secure energy future.”
You can download a report on hydrogen by the IEA called The Future of Hydrogen: Seizing Today’s Opportunities here.
You can also read more about what the UK’s net zero goals could mean for EVs in our recent blog.