Electrical or Pneumatic Components, Which are More Energy Efficient?

Posted by  Mark Stone 22-Oct-2015 09:51:00

Mark is our Fluid Power Technical Manager, based at our Core Competence Centre in Coventry.

festo-pneumatic-componentsWhich 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 pneumatic 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 electric 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 compressed 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 process, a pneumatic gripper is superior to an electric gripper in applications with long cycles and with few gripping operations. A pneumatic gripper requires pressure only once for continuous holding. After that, no more pneumatic energy is required for the duration of the holding operation. An electric gripper, which needs electrical energy for the entire holding operation, can be more energy efficient than a pneumatic gripper only if the application consists of short cycles with a large number of gripping operations.

The application decides

The benefits of electrical components are particularly evident in motion tasks involving high speeds and long stroke lengths. Electric drive technology is generally used more energy efficiently when the requirements are for flexible positioning, variable motion profiles or high speeds. If, on the other hand,
simple, robust handling or high power density is important, pneumatic drive technology offers numerous advantages.

The Total Cost of Ownership should also be taken into account when deciding which drive system to use. Pneumatic drive systems are between 8 and 10 times cheaper to purchase than electric drive
systems. Depending on the stroke length and cycle time, the operating costs may be higher than those for electric drives. However, amortisation times of more than ten years are certainly possible.

The secret is in the mix: The most energy-efficient solution will often be a combination of electric and pneumatic drive technology, as in the case of many of the ready-to-install handling systems from Festo.


Energy efficiency pays off 

Energy consumption in production is influenced by factors other than the choice between pneumatic and electrical technology. Users can obtain concrete results using the Festo model calculator. For example, a company with a three-shift operation and a compressor output of 160 kilowatts can reduce its operating costs by 16% simply by using vacuum generators that operate according to the venturi principle and have an integrated air saving circuit. 

Click here to visit Festo's on-line energy calculator

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Topics: Best Practice, Efficiency, Fluid Power, Transfer & Control, Pneumatics

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