F1 will eventually have to give up its hydrocarbon combustion engines.
And as much as we love them, that’s just a fact, even if we cling on for as long as
possible with biofuels and suss deals with massive oil oligarchs.
At the moment a lot of people are put off by battery powered electric power units. But
while they are nowhere near ready for the energy consumption needs of an F1 race, their
torque and power delivery potention is exciting to consider, even if you’re put off by the
very different noise. Nonetheless, an alternative to battery power
sits in the form of Hydrogen - the most abundant element in the universe.
And while fuel cells are the current focus of Hydrogen power, some people are really
gunning for Hydrogen combustion engines to power F1 into the future so we can have the
big old noise and the old school power delivery mechanism we’re used to.
So let’s look at both. First a quick look at the existing petrol
internal combustion engine. I’ve covered this in detail before so this will be super
simplified and the diagrams in this video are illustrative of the points but not accurate.
Just… bear that in mind. So petrol is a hydrocarbon (a compound of
hydrogen and carbon) which we mix with oxygen, pump into a cylinder and ignite.
The heat from the combustion causes a rapid expansion of gases which drives a piston,
which (along with other well-timed pistons) drives a rotation which ultimately drives
the rear wheels, powering the car. Through combustion, the hydrocarbon fuel and
oxygen from the air react and recombine into carbon oxides that are expelled into the atmosphere
and are generally regarded as bad and a driver of climate change.
Hydrogen fuel combustion basically relies on much the same process but instead of petrol
or gasolene we chuck in Hydrogen gas. As before this mixes with oxygen in a combustion
chamber in a cylinder, burns, drives pistons that eventually power the car.
And from THIS burning in an ideal world we’d get just water as Hydrogen plus Oxygen can
be smashed together into H2O with the energy from the combustion.
But ALAS in the real world the combustion is so hot that it activates the Nitrogen in
the air which is drawn into the chemical reaction process and you end up pumping nitrogen oxides
out of the exhaust, which are bad for people’s respiratory health and also for the environment.
We don’t want to be huffing nitrogen oxides out of our engines if we can help it.
Now I should note that the petrol engines also release some nitrogen but I’m just
demonstrating we’re not solving our emission problems here, especially as combustion engines
also requires oils, some of which burn off into carbon oxides anyway.
Now, the good thing about hydrogen engines is you can run then super lean which reduces
your Nox outputs but this comes at a cost of power, though is very efficient. This is
how you’d expect nitrogen road cars to be tuned.
A lean fuel mix means you increase the amount of air mixed with the fuel before combustion,
so while hydrogen burns well mixed with 34 times its own mass in air it CAN still burn
with an air to fuel ratio of 180:1. This is suuuuper lean, there’s a small amount of
fuel in this mix. Compared to petrol, this is massive. Petrol
can just about do a 30:1 air fuel mixture under well engineered circumstances but normally
runs at about half that. So again, a hydrogen engine can be made very
efficient which reduces nitrogen oxide emissions at a cost of out and out power, which is great
for road cars, especially once you bang a catalytic converter on there to muzzle all
the nox in its tracks. We’ll come back to this engine in a second,
but let’s flip over and have a look at Fuel Cells as an alternate way of using our hydrogen.
This is a completely different beast, which again I’m going to simplify.
Again we have our big tank of Hydrogen gas as fuel. But we’re not going to burn it,
so how do we get the energy out of it? Well first we’re going to put it through
a platinum catalyst which splits up the Hydrogen atoms into its nuclei and its electrons, leaving
a bunch of positively charged Hydrogen nuclei over here, which we’re just going to leave
here for now, and a bunch of negatively charged electrons which are going to do ALL the work.
Electricity, when you pare it all down, is just electrons moving through wires. That’s
all it is. If you can make electrons move, you’ve got electrical power you can put
to work. So now we can send all these electrons to
a Power Control Unit which does a job we’re used to seeing in our Hybrid F1 cars. It either
sends the electrons as electrical current to a motor, which will drive the wheels just
like any electric motor. Or it sends the charge to a battery to store energy for later deployment.
So what you have here is a normal motor/generator ERS type system. You can drive energy to the
wheels and power the car OR you can take energy out of the car to charge the battery. Normal
energy recovery regen stuff. The electrons do circuit back to the fuel
cell and recombine with both the Hydrogen nuclei AND oxygen supplied from the air to
form H2O - just water as a byproduct. NO catch here, just water this time. Clean and done.
This system is very similar to battery powered electric vehicles, you’re just generating
the electrical current by stripping down hydrogen atoms instead of pulling it from a battery.
So you’ll still end up with the whooshy, screaming, electrofuturistic noises Formula
E cars make because you’ve got the same motor-generator at the driving end of the
car. Some people don’t like that so you might
say ‘OK let’s use the hydrogen combustion engine then’. It’s loud and scary the
way F1 should be, like the TRex from Jurassic Park.
But hang on. The nox emissions from this engine are still an issue and not one we can really
dial down but running lean as we want the POWER, right? Flat out racing is the aim (if
not always what we see right now). But emissions are just one problem to solve.
Burning hydrogen in these engines brings in a lot of its own engineering problems.
When you combust petrol, in terms of the space taken up - the volume - you only need a tiny
bit of it in the chamber compared to the air because petrol is a liquid and therefore much
denser than air. So while the ratio of air to petrol is going
to be about 15 to 1 - 15 grams of air to every gram of petrol, the petrol takes up about
100 times less space than the air. Meanwhile in the hydrogen engine, in order
to mix with air at the right ratio, the hydrogen has to take up about a third of the space
because it’s still a gas - and the least dense gas at that.
In the same space you are much more limited in how much hydrogen you can burn compared
to the petrol fuel so a hydrogen engine is now underpowered compared to the petrol equivalent
- potentially by a lot. And the more you compensate to try and bring
this power up, the more you up your nitrogen oxide emissions and the more you make your
engine more complicated and less robust as you further expose yourselves to the other
problems with hydrogen burning - mainly around thermal management.
Hydrogen ignites spontaneously at much lower energy levels than petrol so can much more
easily combust either at the wrong time in the cylinder (reducing power and potentially
causing damage) OR it could even ignite in the wrong part of the engine, causing wear,
damage or even some dangerous, more explosive situations.
Controlling where your hydrogen can get to is vitally important as it can escape into
the wrong places much more easily than liquid fuel.
But the real kicker in all of this is efficiency. The hydrogen in your tank has a certain amount
of stored energy. It’s impossible to convert all of this into useful work, into driving
the car so we measure how much we do manage to use as ‘efficiency’
A hydrogen engine on its own is about 25% efficient - of all the energy available in
the hydrogen fuel, only 25% goes into turning the rear wheels, once it’s gone through
the whole powertrain process. In Hydrogen fuel cells, that jumps to 50%.
We can squeeze twice as much energy out of this hydrogen than we could by burning it.
This means we can have fuel tanks half the size, which is a huge benefit as Hydrogen
takes up a lot of space. It also means we spend half as much on buying
the hydrogen in the first place. And hydrogen is expensive. It’s expensive to make, it’s
tricky to store and it’s hard to transport. With all that in mind why on earth would you
waste your precious hydrogen on a power unit that essentially wastes half of it compared
to fuel cells? Fuel cell power units are cleaner, more efficient,
cheaper to run and have energy regeneration built right in for added efficiency and flexibility.
But now let’s think about hydrogen overall. There are still serious issues with hydrogen
for this kind of thing and we’ve just touched on some of them.
Storage and transport are big problems and we are still working hard on this. We can
either liquify it, which requires absurdly robust Dewars dropped to incredibly low temperatures.
We can compress it as a gas to about 300 times smaller than the space it would take up in
the air. This is how it’s stored inside cars as fuel. Again this requires robust,
well tested containers to prevent accidents. Alternatively we can chemically store it which
means locking it inside a chemical compound and breaking it out later on, which… has
yet to be perfected in a way that makes large scale practical sense. And it’s less efficient.
But they’re working on it. So at this point as the back end of a fuel
cell power train is essentially the same as an battery powered power power train anyway,
what advantages does it have over the ‘Formula E’ way?
Well, while hydrogen currently struggles in terms of ‘size’ - that stored hydrogen
gas takes up a lot of space - it might beat it into terms of weight. Batteries are still
very very heavy for their energy storage and hydrogen has them beat by a factor of about
ten to one. You could argue that a hydrogen tank is technically
refuelable, though pit stops would probably take in the range of minutes if you did want
to shrink the tank and go that route. That could lead to races taking wonderfully bizarre
new shapes with cars battling for the lead 2 or 3 laps apart through some periods of
the race. At the moment, creating batteries for electric
cars is quite an energy intensive process and also required mining for the materials
like Lithium needed in its composition. This is not a super environmentally robust part
of its life cycle. The huge majority of hydrogen manufactured
today is also incredibly unfriendly - it’s stripped out of methane via cracking which
results in CO2 emissions and involves huge energy losses in the process. So that’s
bad. But you can make hydrogen very cleanly through
electrolysis. We just don’t have any large scale infrastructure up and running for that
yet. But we could. But let’s come back to efficiency. Lithium
Ion batteries at their current level only lose about 17% of the energy you put into
them through inefficiencies in charging and discharging. A hydrogen fuel cell only gains
you back about 50% of the energy you put into harvesting the hydrogen in the first place.
At present, with the way technology looks to develop and seeing what it’s suited to,
battery powered electric power trains still look set to be the future driver of motorsport,
though I continue to watch the intense development of future tech with eager eyes