Hydrogen cars: the greatest challenge?

Blog post posted on 04/07/17 |

Today, all sorts of engine technologies are fighting for prominence. There has been major development in battery powered cars, hybrids and plug in hybrids.  Diesels have become ever more efficient and cleaner (yes, really) and petrol engines now rival diesel for fuel efficiency, at least on some types of journeys. 

But the very first vehicle powered by an internal combustion engine actually dates from a couple of centuries ago, and it ran on hydrogen.  Built by Frenchman, François Isaac de Rivaz in 1808, it wasn’t very practical; the driver had to operate the valves by hand, press a button to fire the spark and the range was around 100 metres, but it was a first, and since the only exhaust product was water, it was pollution free. 

For the past 15 years or so, I have represented IAM RoadSmart on various advisory bodies looking at how we can reduce the pollution from vehicles. Throughout this time, the mention of hydrogen usually provoked the sceptical response, “Hydrogen is the fuel of the future – and always will be”; a legacy of the many failed attempts to harness the clean power of this plentiful gas. 

Nevertheless, engineers have continued to pursue the goal of a reliable hydrogen power unit because of that clean exhaust. The only thing you get when you burn hydrogen is water, which is completely harmless. No poisonous oxides of nitrogen to give us heart disease, no soot to trigger cancers, no carbon dioxide to fry the planet.

Getting the power plants to work reliably has been tricky, but this has now been overcome using fuel cells to generate electricity to power an electric motor to drive the wheels.  Most of us will remember the electrolysis experiment we did at school with a couple of electrodes in a flask of water which split the water into hydrogen and oxygen. 

Fuel cells reverse that process, combining hydrogen and oxygen to produce electricity. Making fuel cells that work reliably, efficiently and safely is complex technology but engineers are finally mastering it.

The much bigger challenge is how to manufacture hydrogen on a large scale.  There are two ways of producing hydrogen commercially; reforming methane, which is dirty and energy intensive, and electrolysis of water which can be very dirty if a coal fired power station generates the electricity to do it - and we are already short on electricity generation capacity. 

The current techniques produce so much pollution and greenhouse gas from the manufacturing plant that conventional engines are a much greener option overall.  Nevertheless, Toyota, Honda, Kia and Nissan have hydrogen fuel cell powered cars on the market today, albeit in small numbers, and the UK government is committed to investing in a hydrogen fuel infrastructure to re-fuel these cars. So how can enough hydrogen be produced without creating even more environmental damage?

The best argument for hydrogen is to think of it as a way of storing energy. Thanks to various politically motivated subsidies and initiatives, we now have substantial wind and solar generating capacity which produces loads of electricity when we don't want it - during the day for solar power, when lights are off and people aren't cooking dinner and watching TV, intermittently and unpredictably for wind. 

We can't store that power at the moment so turbines stand idle and the solar power is not used.  Tidal energy will at least be predictable but a lot of tides still peak when the power's not needed. 

One idea is to use surplus solar/wind/tide power to electrolyse water and produce hydrogen which can then be stored and used to power vehicles.  The potential is substantial; only a small percentage of the overall annual transport energy consumption, but nevertheless significant.   

This of course means the generating companies, motor industry, fuel industry and government departments all agreeing to work in a co-ordinated and co-operative manner, putting the public good above individual interest. 

Maybe that’s the biggest challenge of all.

Tim Shallcross, IAM RoadSmart’s, head of technical policy and advice