Electrolysis of water in cars is a fuel economy mirage
Two month’s ago, in the September 2008 issue, I answered a
question from a reader concerning the supposed manufacture of Browns Gas. This
is the mixture of hydrogen and oxygen evolved from the electrolysis of water. It
is called Browns Gas in some sort of canonisation of the ratbag engineer (Yull
Brown) who promoted the process in Australia some 30 years ago. This Browns gas
is injected into the engine’s inlet manifold to be burnt in the cylinders.
Depending on the site where you find this topic, this is claimed to give large
gains in fuel economy.
Confronted with this nonsense, I gave a fairly detailed answer
on the question in the hope that it might kill off the whole silly idea. But
guess what? Since then we seem to have had a rash of questions on the topic.
Mostly these questions are related to pulse width modulation circuits which
could be used to drive the electrolysis process and also control the current
drawn, as it tends to "run away". None of the people who contact us on the topic
have any idea that it is just a silly idea. This is another consequence of a
population who have very little knowledge of science and technology.
Obviously my attempt to discredit the whole concept has so far
been a complete failure. There seems to be an increasing interest in the
process, possibly driven by the production of hydrogen-powered prototype cars in
the USA. It should be obvious that this is a technological dead-end, but that is
another story, associated with the attempt to kill off the electric car in the
USA some years ago. So without repeating all of what I wrote in the September
issue (pages 89-90), let’s attempt to dispassionately review the topic of
producing hydrogen in a car so that it can be burnt in the engine.
First of all, the electrolysis of water into hydrogen and
oxygen is a simple but energy intensive process, even when platinum electrodes
are used as a catalyst. The popular internet process using stainless steel
electrodes is much less inefficient. To generate any significant amount of
hydrogen, you need large amounts of energy. That energy has to come from the
car’s electrical system (ie, battery and alternator) driven by the engine and
fed from the petrol tank. It should also be obvious that you also need to carry
substantial quantities of water – which is even heavier than petrol or
So we attempt to run a very inefficient chemical process in
order to get some hydrogen and oxygen to be used in the car’s engine. The
claimed result of this process is an overall improvement in fuel economy – as
much as 15% according to some claims.
To me, this just beggars belief. If it was that easy to get
such a major increase in fuel economy, why hasn’t a single car manufacturer ever
done it? Why have the car manufactures resorted to ever increasing complexity in
their engines to eke out fuel economy improvements over the decades? Why have
Toyota and Honda developed even more complex hybrid cars such as the Prius,
Insight, Civic and others, to get better fuel economy? Confronted with these
questions, some people start to mutter about oil company conspiracies . . .
Just in case, people don’t get the message, this process does
not improve overall fuel economy in the slightest – it can only lead to a
On the positive side, I suppose it is good that so many people
are thinking about ways of improving fuel economy in cars. It is just a great
pity that more people cannot see the blindingly obvious approaches to saving
fuel: (1) Drive a light car with a small engine and (2) drive less.