HIGH TIME FOR HYDROGEN?

Despite being a clean fuel, hydrogen has struggled to take off so far. However, it could still play a major part in the drive to slash emissions

- Claire Evans

AIthough it seems like everyone is setting their sights on battery-electric vehicles BEVs( to enable us to reach the point where all cars are emissions-free, they are by no means the only solution, and not necessarily the most effective. Hydrogen is a different source of clean energy that could help countries realise their green ambitions quicker and more affordably.

Given that hydrogen is the most abundant chemical element in the universe being found in water, for example( and can hold energy in a similar way to petrol and diesel, its potential as a fuel for vehicles is almost limitless in theory.

It can be fed directly into suitable internal combustion engines, or it can be combined with oxygen in an on-board fuel cell to produce electricity, with the only byproducts being water and heat. And although it has a lower energy density than petrol and diesel when it’s burnt directly, the best hydrogen fuel cell electric vehicles FCEVs( can convert up to 80% of the energy they create into propulsion, versus around 40% for petrol and diesel.

So, why isn’t hydrogen fuel used much more widely already? Well, hydrogen has to be extracted from other things such as water or natural gas( via electrolysis, and this process is not only expensive and time consuming but also requires a lot of energy in itself. In the past, this has mostly come from gasfired power stations, but the necessary energy can now be generated sustainably at solar, wind or nuclear-powered sites. Safety is also an issue; the compressed hydrogen is stored at very high pressures, so FCEVs’ fuel tanks have to be immensely strong and able to withstand crashes.