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Researchers Found a Way to Turn Spent
Coffee Grounds Into Biodiesel More Efficiently
Significant savings in time and energy!
It’s no longer new that coffee wastes are being
turned to biofuels. Several coffee shops right
now advocate this green conversion. But
researchers have found a new way to do this, far
more efficient than previous methods.
To turn spent coffee grounds into biodiesel, the
usual process involves mixing of the grounds
with hexane and cooking the mixture at 60°C
for between 1-2 hours. The hexane is then
evaporated to leave behind the oils. Finally, to
make the biodiesel, methanol and a catalyst are
added. There is a by-product of glycerol which
also needs to be separated from the fuel.
This process is shortened into just one step
by chemical engineers at Lancaster University.
They were able to make the existing process
of many stages into one known as in-situ
transesterification, which combines extraction of
the oils from the spent coffee grounds and the
conversion of it into coffee biodiesel.
Dr Najdanovic-Visak, a lecturer in Lancaster
University’s Engineering Department, said, “Our
method vastly reduces the time and cost needed
to extract the oils for biofuel making spent coffee
grounds a much more commercially competitive
source of fuel.
“A huge amount of spent coffee grounds, which
are currently just being dumped in landfill, could
now be used to bring significant environmental
benefits over diesel from fossil fuel sources,” he
added.
It was discovered that in 2014, more than 9
million tonnes of spent coffee grounds were sent
to landfill.
Meanwhile, the researchers estimate that the
process could potentially produce 720,000
tonnes of biodiesel annually from spent coffee
grounds.
Producing biodiesel in the new method still
involves methanol and a catalyst, but without the
hexane.
The researchers also discovered that the optimal
time for the process was 10 minutes to gain the
same yield of oils from the spent coffee grounds,
offering significant savings in time and energy
from the previous method.
Oil & Gas Leaders • June 2017
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