HYDROGEN FUEL CELL VEHICLES : THE SAFEST CHOICE?
At Bramble Energy, we pride ourselves on our involvement in educational outreach activities; whether that’s demonstrating how fuel cells work at events and exhibition such as the Shell eco-marathon (click here for more) or dispelling the rumours surrounding the safety of hydrogen as a fuel.
This got us thinking about the audiences we don’t get to interact with regularly who may not have had the platform to discuss their hydrogen and fuel cell concerns.
So what better place than our blog for us to demystify some of the myths surrounding hydrogen as a fuel for transportation.
When you think about hydrogen as a fuel, you probably start picturing the Hindenburg airship fully ablaze hurtling towards the unsuspecting ground. A dangerous fuel source perhaps? Or perhaps not.
The Hindenburg was not a craft powered by hydrogen, but instead, filled with it; hydrogen is the lightest and most abundant in the universe and therefore it was chosen to provide the lift required to float the craft. There was a suspected ignition source that day (the source of which is still not completely clear) that caused the flammable hydrogen gas to burn and thus bringing down the craft.
However, when any fuel source is handled in a manner unfit for its purpose its dangerous properties become all the more exacerbated. And that is exactly what happened in the Hindenburg disaster – a huge balloon full of hydrogen was exposed to an ignition source which as you may know from a kids science experiment causes a very big bang
Hydrogen is of course a flammable gas. But what tends to be forgotten is that all fuel is in fact by its very nature flammable and therefore potentially dangerous. It is this very property that we require from the fuels such as petrol and diesel that we feed our internal combustion engines (ICEs) as small amounts of fuel combust to move the pistons of our engine up and down.
Let us consider a safety case with 4 identical cars with the following drivetrains; the first a petrol (or diesel), the second purely battery, the third powered by CNG and finally the fourth with a hydrogen fuel cell.
If each of these cars undergo an identical accident in which the fuel tank (or battery pack) is fractured or punctured allowing the fuel to escape in the presence of an ignition source, which vehicle do you think provides the safest reprieve?
The petrol / diesel vehicle
A puncture to the liquid fuel tank can result in a spillage and pooling of the fuel on the tarmac. The introduction of a ignition source to the pool of fuel is likely to cause the car to become engulfed in flames and burn up over a few hours.
There’s a video of a similar incident HERE
The battery vehicle
You’ve probably read about or seen several videos of accidents involving battery cars in the news over the past few years. When a battery pack is punctured or damaged and any of the cells discharge rapidly, catching fire, all of the cells in the pack also catch fire. This will set the vehicle alight and as you’ve probably seen in the news, these fires are not only difficult to handle, but also they can last for many days before the wreckage can be contained.
Read more about these type of events HERE
The CNG vehicle
With a compressed natural gas vehicle, a puncture in the fuel tank will cause the compressed gas to escape quickly through the fracture point. Introducing an ignition source will cause the venting gas to flare until the tank empties which is likely to take a few minutes. The damage caused by this is likely to be quite severe causing large burn marks and singes around the flare point on the vehicle.
The hydrogen vehicle
Finally, an ignition source introduced to a puncture in the hydrogen tank of a fuel cell vehicle will react similarly to that of the CNG vehicle; except as hydrogen is the lightest element known to man, it vents incredibly quickly and directly vertically; the flare is likely to be exhausted within a matter of seconds. The hydrogen flare can be noisy but has no colour and radiates no heat, resulting in very little evidence of an incident flame anywhere on the vehicle.
Click HERE to see a video that perfectly depicts the safety case discussed above comparing the petrol and hydrogen fuelled vehicles as shown below
In reality, with any fuel source it is the mindset and handling (petrol station development and etiquette or the inbuilt safety mechanisms within the vehicle for example) that governs how safe a fuel can be.
Dr Vidal Bharath
Head of Operations
What do you think about the safety of hydrogen fuel cell vehicles? Sign up to our newsletter for quarterly updates HERE, keep an eye on our website www.brambleenergy.com and of course follow us on social media @brambleenergy. Have any comments or questions? Get in touch at email@example.com