Energy efficiency as a corporate goal
“Energy efficiency is a process.”
Dr. Dietmar Tilch, Factory Automation Technology Strategy, Bosch Rexroth AG
Mr. Tilch, what does Rexroth understand by “energy efficiency”?
Energy efficiency is not something static, but rather a process with the goal of continually improving our customers’ energy balance. This means reducing energy requirements across the board without impacting productivity, and ideally achieving higher productivity at lower consumption.
A lot of businesses are looking to cut costs right now. Is it even possible to finance energy efficiency in the current situation?
Energy efficiency pays of in relation to the operating life of the machine or plant. The operative principle here is: cheap products are a one-time saving, while efficient solutions save every day! But energy-efficient solutions can compete with conventional project planning even in short-term investment calculations, as they often embody special additional system properties that save money and effort elsewhere. For example, our IndraDrive Mi system proved superior to a solution with standard frequency converters in a package sorting system. Our system eliminates the switchgear cabinet that would otherwise be necessary, as well as a large part of the wiring and the installation work. This offsets virtually all the additional investment costs. The benefit of energy saving extends over the entire operating lifespan.
How do you start improving your customers’ energy balance?
Rexroth has developed its own system for this. We bundle a number of actions that achieve results across all drive and control technologies of all brands. In mobile applications, intelligent systems such as the hydrostatic regenerative brake system (HRB) can cut fuel consumption by up to 25 per cent. Rexroth also offers efficient solutions for systems used in wind turbines, in harvesting the oceans’ energy and in solar systems. Our drives and mechatronic modules improve the energy efficiency of plant equipment and factory automation.
Bosch and Bosch Rexroth participate in research projects
Can you describe this systematic approach? What levers do you use?
We have identified four main levers for increasing energy efficiency: efficient components, energy recovery, demand-driven energy supply and energy system design. We combine these levers in the Rexroth 4EE System: “Rexroth for Energy Efficiency”.
Rexroth 4EE – what exactly does this name promise?
Rexroth for Energy Efficiency is not just a marketing slogan but a technological system. Rexroth 4EE bundles, structures and focuses a broad range of technologies and solutions that all contribute to the intelligent use of energy. By looking at the overall system – from design to operation and maintenance – 4EE opens up enormous efficiency potentials that can be realized today. We ourselves were somewhat surprised when we noticed in the course of preparing the 4EE system how much potential can be realized by applying the four levers, and how easy it is to realize much of this potential. Also, our long history of innovation puts us in the fortunate position of being able to offer our customers numerous solutions and comprehensive consultation competence from a single source, so that we can support them effectively in increasing their energy efficiency.
Can you point to a solution that exemplifies and illustrates this?
First, I’d like to emphasize again that we do not believe that there is single “miracle technology”, a single massive lever. Energy efficiency is always the product of the interaction of a wide variety of factors, and also depends on the particular application. There are, of course, some solutions that are especially powerful. On the production planning and consulting level, for example, we have our controller-level tools for energy and cycle-time analysis, EGA and CTA . These tools enable the data of all subsystems of a machine to be accessed and tracked. This means that all the sub-processes can be time-optimized and made to run in parallel. The energy analysis enables recording of the energy consumption of the individual components and analysis of how the individual components are controlled. Graphic representations then help the engineers determine the ideal tradeoff between energy consumption and production performance.
How much energy can be saved by pulling on all the 4EE levers?
The energy-saving potential is particularly high wherever energy is converted into another form. This is the case, for example, in hydraulic drives. The lever of demand-driven provision of hydraulic energy – measured in pressure and volume flow – is particularly significant here. Variable-speed pumps represent an ideal solution here, as their volume flow is controlled via the drive speed and is no longer throttled using valves.
In the project engineering for a hydraulic plastic press, it proved possible to achieve energy savings of 78 per cent compared to conventional project engineering – and this lever was paramount. Another example is moving masses. Important features here include a smooth and gentle motion process as well as the reclamation of braking energy for subsequent acceleration steps. By using common intermediate circuits and the ability to feed power back into the mains, our drives are capable of exchanging energy flows between individual axes.
In the package sorting system described above, electrical energy is generated when braking the diverters. This energy is returned to the system. This alone reduces the energy requirement by up to 15 per cent. By applying all 4EE levers – not just recovery but components, need-based control and an overall system perspective – we achieved energy savings of around 35 per cent in this project. And at a cost that is fully comparable with conventional solutions!
More information:
www.boschrexroth.com/energyefficiency
Contact:
drive-control@boschrexroth.de
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