Used chip fat with smelly floating bits…any takers? You could
pour it down the drain, throw it out, or use it in your car. Yes,
use it in your car! Diesel cars can be converted to run on old
vegetable oil for about £700. Old vegetable oil, or chip fat, is
free to use whereas diesel is well over a pound per litre. Not a
bad deal!
Green and free, so what's not to like?
Would you like to drive a car that smelled like a chip shop? Or
spend hours filtering out the gunky bits from litres of vegetable
oil? Some people do manage to get past these problems - or maybe
they just put up with them. In fact, vegetable oil is a biofuel (a
fuel that comes from plant materials rather than petrol) and people
have been using old chip fat as a greener, and cheaper, substitute
for fossil fuels for years.
This car runs on
biofuel
Why don't we use it all the time?
Chip fat is made of hydrogen and carbon atoms. If we could get
the hydrogen atoms out of these molecules we could use it as a
really good clean fuel. This is because hydrogen contains lots of
energy. React it with oxygen and that energy is released with a big
bang and a little bit of water as a waste product. It is just about
the perfect fuel.
The problem is that it would take a lot of energy to split the
hydrogen away from the carbon, because it would have to be heated
to very high temperatures: over 800 degrees Celsius. This would use
more energy to heat it than you can get out of the hydrogen in the
first place. Also, you would get a lot of carbon dioxide, a gas
thought to be partly responsible for global warming. That wouldn't
be very green at all.
Bring on the scientists!
Leeds University researchers have come up with a way of
splitting the hydrogen and carbon without using too much
energy.
How do they do it?
The trick is to take a nickel catalyst (a substance that speeds
up a reaction without itself being affected) and blast it with air.
This causes it to react and forms nickel oxide. The process is
exothermic, which means it gives out heat - lots of it! This means
a huge saving in energy as the exothermic process boosts the
temperature, so you don't have to. The less you have to pay to
raise the temperature, the more cost effective the process will be.
The chip fat can then be split into hydrogen and carbon
dioxide.
That's not even the most exciting part. The best trick is saved
till last. A special 'sorbent' material is used to absorb the
carbon dioxide. Sorbents have huge surface areas and a structure
like a microscopic sieve to trap and hold unwanted molecules. This
also helps sustain the reaction so that it will run indefinitely.
Hey presto, cost effective hydrogen from a waste material.
This means that chip fat really could be the fuel of the future.
You'll never look at a bag of chips in the same way again!
Did you know…
Choo choo! The Queen's Royal Train runs completely on 100 per
cent recycled chip fat. I didn't know Her Majesty liked chips that
much!