Page 12 - trends in automation 1.2013

Energy efficiency – a technological comparison
The right choice
Which are more energy-efficient – electrical or pneumatic
components? What advantages does one technology have
over the other? Many experts believe that the ideal solution
is a combination of both. However, this is a situation where
prejudices often prevail over facts. A comparison is the ideal
way to ensure clarity.
Energy efficiency depends on the
application. “This must be clearly
defined before a user chooses the
drive technology – electric or pneu­
matic or a mixture of both,” explains
Roland Volk, energy efficiency consultant
at Festo. But what does this mean in
concrete terms? Only a direct comparison
of two identically sized drives – one elec-
tric and one pneumatic – is able to clearly
show the benefits of each technology.
In our comparison, motions are performed
from point A to point B. This results in
very different energy consumption values.
Task 1: Moving and holding
In the case of motion without additional
process force, an electric drive consumes
only one-third (25 Ws) of the energy that
a pneumatic actuator needs (78 Ws). For
the function ‘pressing with process force’,
both drives roughly consume the same
amount of energy, i.e. between 20 and
30 Ws. If, however, the drives are required
to hold a certain position, the energy
consumption of the electric drive shoots
up to 247 Ws. This is more than 22 times
as much as the energy consumption of
the pneumatic drive (11 Ws).
The pneumatic drive benefits from the
fact that it requires energy only for the
brief moment in which pressure is built up.
The holding process itself can be carried
out completely without any fresh com-
pressed air supply and there are thus no
energy costs. The electric drive, on the
other hand, requires electricity constantly
in order to remain in the desired position.
The longer the holding process, the higher
the energy consumption of the electric
drive compared to the pneumatic one.
Task 2: Gripping
A comparison of electric and pneumatic
grippers produces similar results. The
comparison shows how finding the right
solution depends on a clear definition of
the application. If we consider the energy
consumption during the gripping pro-
cess, a pneumatic gripper is superior to
an electric gripper in applications with
“Energy efficiency
in automation is
always dependent
on the industrial
application.”
Roland Volk,
Innovation and
Technology
Management at Festo