It’s the lightest element in the periodic table and also one of the most abundant –every molecule of water on the earth’s surface comprises two hydrogen atoms and one oxygen atom. It’s highly flammable (even explosive - remember the Hindenberg disaster?) and it's what powers the sun that shines on us all (if we're lucky). So maybe it’s not such a crazy idea for a fuel source.
That’s certainly what proponents of the so-called Hydrogen economy reckon anyway. The idea being that replacing the wide range of petroleum based hydrocarbons we rely on today (oil, petrol, natural gas, coal and so on) with hydrogen would not only be greener but also make managing our remaining carbon emissions a lot more straightforward. A boon for business, right?
Hydrogen’s great secret is that it is so clean burning – recall if you will your GCSE chemistry: combining hydrogen with oxygen (from the air) yields energy and water only. No carbon dioxide, no NOx, no acidic sulphur compounds.
The lightest element in the periodic table
So with the promise of zero emissions (at least from the tailpipe) no wonder that car makers have been fiddling about with hydrogen as a fuel for decades – although it’s only very recently that the first hydrogen powered vehicles (like the Toyota Mirai reviewed here) have come to the market, and even then they are really esoteric ‘proof of concept’ products.
The fuel cell technology used by the Mirai and its fellow FCVs is genuinely amazing, but even deep green buyers may be slightly put off by the fact that there are currently only five (yes five) hydrogen filling stations in the whole of the UK. Gulp.
Hydrogen is not without other drawbacks either - it may be abundant in water and many other compounds, but molecular hydrogen (the kind required for fuel) is not found anywhere in nature. It must be manufactured and that costs, both in money and carbon emissions.
Its green credentials are dented rather by the fact that pretty much all of the hydrogen produced commercially at present is made by treating natural gas with high-temperature steam. Plenty of CO2 there. So a purist would say that far from eliminating carbon emissions, you are simply moving them to a different place (the same argument applies to battery electric cars like the Tesla or Nissan Leaf).
But the theoretical advantages of hydrogen as a fuel are not limited only to cars. One of the biggest criticisms of renewable electricity from wind power (of which the UK now has an installed capacity of 13.5GW), is the difficulty of matching supply and demand. It can be blowing a gale in the middle of the night when demand for electricity is low because we’re all asleep, and conversely dead-calm during the daylight hours of peak need. (This is the reason why nuclear is often cited as the ideal ‘baseload’ back up for wind, but as the shenanigans over Hinkley Point demonstrate, it comes freighted with its own substantial cargo of practical problems).
The sun - a giant ball of burning hydrogen
The fundamental problem with electricity is that it cannot be cost-effectively stored. There simply aren’t batteries big enough or chap enough at present to cope with National Grid-level requirements, so any surplus wind-generated power simply goes to waste.
But that surplus could be used to make hydrogen by another process, passing an electric current through water to split it into Hydrogen and Oxygen, called electrolysis. And as Dr Paul Dodds from UCL’s energy systems department points out ‘Compared to electricity, you can store hydrogen relatively cheaply’ - by pumping it into underground salt caverns, for example.
The stored hydrogen could then be used either directly (in public transport perhaps – there are a handful of hydrogen powered busses already plying the streets of London and Aberdeen) or burned in power stations to generate electricity at the time when it is actually needed.
Don't expect any bargain energy bills though - even boosters admit that using hydrogen for this so-called 'peak lopping' would be a pretty expensive and inefficient business.
There is even talk of using hydrogen as a greener alternative to natural gas as a fuel for homes and businesses – Northern Gas Networks, which manages gas distribution across Yorkshire and the north-east, has proposed a city-scale experiment to substitute hydrogen for natural gas across the whole of Leeds (760,000 customers) by 2030. So maybe one day you’ll be able to refuel your hydrogen-powered car by plugging it into the gas main at home or at work.
Well, it might happen. Call us luddites if you will, but here at MT we're not convinced that the hydrogen economy is ever really going to catch on. The costs would certainly be great and it's not clear that the benefits would be big enough to justify them.