German industry could save twenty-five percent of its energy consumption by consistently applying existing efficiency technologies. While industry managers adopt a new way of thinking, scientists are working on the vision of a resource-efficient factory. 12/2009
Inconspicuous little boxes hang from giant metal containers above the shopfloors of Volkswagen Sachsen in Saxony. Litte boxes with a considerable energy-saving effect. Because inside are frequency converters which ensure that the motors of the ventilation system housed in the containers are running at an optimal speed. "They save us 13 million kilowatt hours a year in the whole factory," reports Horst Döhler, head of the Technology Department at the VW plant in Zwickau. "That works out to 7,000 tons of CO2." The investment in the frequency converters was recouped in less than a year thanks to savings in electricity costs. The results are so compelling that another European VW plant plans to adopt the same solution. This is made easier by the fact that all the company's European plants are equipped according to uniform standards. The regular exchange of information also helps, energy efficiency having become one of the main topics in the company's Energy Working Group headed by Döhler.
In purchasing plant and production technology in the past, VW had been guided mainly by functionality, productivity and investment costs. Plant technicians could later try to optimize the installed equipment and achieve the most energy-efficient operation. In the future, VW plans to go one step further. "We're influencing the energy efficiency of the machines and equipment being built for us," explains Zwickau Planning Chief Reiner Tunger. "Energy efficiency is becoming a competitive factor in choosing our suppliers." Tunger is particularly interested in machines with grid-connected measuring technology, allowing current energy use to be centrally monitored and evaluated.
But this kind of conversion can only take place in stages, he says, for reasons of cost. For the time being, he sees no need to order new machines and equipment for the VW plant in Zwickau, where Golfs and Passats are manufactured. The retooling of existing manufacturing equipment planned for the coming year can be handled by the factory's own tool shop. Still, Döhler plans on having to replace several electric motors with new, more efficient units. A Europe-wide company standard, established in 2008, requires all electric motors installed in new equipment or replaced during maintenance to meet the requirements of efficiency class I. The higher price compared to conventional motors already pays off after 1.3 years thanks to more efficient energy use. New and converted machines and equipment in the Zwickau plant will also have a master switch with measuring technology. This enables the company to monitor and evaluate energy consumption over time and throughout the production process. Unnecessary electricity consumption in standby mode, for example, can thus be detected and eliminated.
German industry uses a total of 5,640 petajoules of energy annually. That's 40 percent of national primary energy consumption, according to the study "Energy Efficiency in Manufacturing" conducted by several Fraunhofer institutes on behalf of the Federal Ministry of Education and Research. To be sure, in the years 1995 to 2005 the energy intensity of production industry sank five percent to 11 megajoules per euro of value added. Yet according to surveys of 450 industry managers, the potential for energy savings is still much greater. "It was estimated that in the medium term – in other words, over a period of five years – energy savings of 25 to 30 percent are possible, mainly through the use of efficiency technologies," reports Andreas Sterzing, executive chief engineer at the Fraunhofer Institute for Machine Tools and Forming Technology (IWU) in Chemnitz, which coordinated the study.
Exploiting this potential for savings will require a paradigm shift among decision-makers, scientists claim. "Maximum profits from minimum capital has to give way to maximum profits from minimum resources," the study says. But it's still a long way there. Because the study also showed that only 12 percent of those surveyed considered energy costs a significant factor in investment decision-making. More than half attached little or no importance to them at all. Yet it seems that many managers are beginning to rethink things. In recent months, the IWU has received an increasing number of inquiries from industrial enterprises wishing to improve resource and energy efficiency and make use of renewable energy sources in production processes. "Some of them even want a degree of energy self-sufficiency, to be independent from local energy suppliers over a certain period of time," Sterzing says. "The main focus is on reducing costs, but the growing awareness of limited resources has meanwhile become an important consideration."
Particularly suited to energy-saving projects are so-called cross-sector technologies suppling heat, mechanical energy and light, and which work the same everywhere. Successful projects can therefore be easily applied from one sector to another. According to a study entitled "Potentials and Economic Effects of an Ambitious Energy-Efficiency Strategy for Germany" conducted by the Federal Ministry for the Environment, these technologies account for 65 percent of total end energy consumption in German industry. A lot of energy can be saved by using more efficient motor applications. Optimized systems for air compressors, pumps, blowers and chillers could reduce the annual end energy consumption of German industry by 101 petajoules by the year 2020. A further 111 petajoules could be saved by using more efficient technology in lighting, heat generation, drying and industrial furnaces. Together this amounts to nine percent of the overall end energy consumption of German industry in 2007 – a sizable sum.
A rather widespread cross-sector technology in industrial enterprises is compressed air, which plays a growing role in pneumatic systems and tools. The German Energy Agency dena reports that 62,000 compressed-air systems are installed nationwide in various areas of production, having an annual power consumption of 14 billion kilowatt hours. According to dena, compressed-air systems could save five to fifty percent of the energy they consume. The investments needed to do so would be recovered in less than two years. The dena "Energy Efficiency" initiative's publicly accessible project database mostly contains examples of small enterprises, such as Haus Cramer brewery in Paderborn, a convincing example indeed. The brewery made a one-time investment of 62,500 euros to modernize its compressed-air system and now saves 55,000 euros a year on energy costs as well as preventing 300 tons of CO2 emissions.
A company-wide energy management program was developed by Evonik Industries. The technology firm uses an in-house questionnaire to provide individual production sites with initial suggestions for potential energy savings. Interdisciplinary teams of experts are then formed to analyze the whole of energy processes and develop further suggestions for optimization. To date, 26 of Evonik's 109 chemical production sites have been evaluated in this manner, revealing potential savings of between 4 and 25 percent of annual energy costs. The optimization of a postcombustion unit at the Münchsmünster production site seems to have been a particular success. The unit burns the exhaust air of a production plant with the help of a natural gas burner. The energy gained in the process is used to generate compressed air, cold and heating steam. Evonik invested 500,000 euros to overhaul and modernize the system. As a result, its annual natural gas consumption sank 72 percent and yearly CO2 emissions were reduced by 9,300 tons. And thanks to energy cost savings, the investment was paid for in less than a year.
High-performance materials such as ceramics can also help save energy in production plants. The use of durable, wear-resistant key components reduces and prevents downtimes caused by servicing and maintenance. Hence, they substantially promote more energy-efficient production processes.
FCT Ingenieurkeramik in Rauenstein, Thuringia, for example, developed ceramic guide and groove rollers for a stainless-steel manufacturing plant. The new rollers are considerably more durable than the steel ones used before. The old ones were often worn and in need of replacement after 40 tons of rolled stainless-steel wire. "We now only need to inspect them every 600 tons," reports Karl Berroth, managing director of FCT. A longer service life not only means higher productivity but energy savings as well. Because even though the wire rolling mill stood idle for 15 minutes three times a shift whenever the rollers had to be changed, the machines still had to be heated and cooled. Now the rollers last two to three shifts. The higher cost of ceramic groove and guide rollers is recouped in only a couple of shifts, says Berroth. Its success at the stainless-steel plant helped FCT receive a follow-up order at the Hamburg plant of building steel wire manufacturer Arcelor-Mittal. "The economic gain at this wire mass-producer is even greater," explains the director of FCT.
Energy-conserving projects of this sort could be implemented much more often if it weren't for a number of obstacles. A study conducted by the Federal Ministry of Economics and Technology (BMWi) points to an information deficit and financing as the main problems. Larger enterprises often employ an energy commissioner and systematize the efficient use of energy. Smaller enterprises, on the other hand, frequently lack the necessary expertise. Many aren't aware of the potential for savings or simply underestimate it. Very few buyers, for example, are aware that the life-cycle cost of a large electric motor is predominantly the cost of the electricity used to run it. The initial outlay is small by comparison. According to the BMWi study, even greater obstacles exist on the financial end. Because energy-saving investments always have to compete with other investments that are more lucrative or more in the company's core business area.
None of these obstacles to existing energy conservation methods, however, is keeping researchers at IWU in Chemnitz from looking into even more radical efficiency technologies. They have recognized, for example, that traditional manufacturing processes for gear parts which use cutting techniques such as turning and milling are quite material- and energy-intensive. In the long run, an "outstanding potential for greater energy efficiency in metalworking" could be tapped if these metal-cutting manufacturing processes were replaced by more effective cold-forming procedures, the Fraunhofer study says.
One of these cold-forming procedures is the cold rolling of so-called running gears for gear units. Udo Hellfritzsch, team leader for running-gear technology at IWU, is working on such a procedure. It almost looks like a magic trick when he demonstrates the technology they've developed so far. In a profile rolling machine he places a smooth, shiny steel blank between two toothed rollers. At the press of a button the rollers begin to rotate, sink their teeth into the blank from two sides and turn it with them. Twenty seconds later they release the blank, which now has teeth itself, and after fine machining can be used as a gear wheel in an automobile transmission.
A gear wheel made this way is not only more stabile than a conventionally manufactured one shaped by cutting the metal. According to Hellfritzsch, up to a third of the material and half the manufacturing time can be saved as well. Less steel and machine time, of course, mean a lower energy input. "We reckon with energy savings of 15 to 20 percent if the gear wheels are mass-produced," the researcher estimates. And if the overall manufacturing process is taken into account, including the production of blanks, the savings effect should be even greater. Hellfritzsch and his colleagues are still trying to improve the technology. It will be another four to five years before we see the first mass-produced cold-rolled running gears, he says.
In the short term, even conventional machine tools can be operated more efficiently than they are at present, the IWU study indicates. Machine tools currently need four times as much electricity for their base-load operation than the amount required to actually work the materials. Not more than half of their operating time is spent processing materials. The scientists recommend reducing energy consumption by lowering the machines' base load and avoiding peak loads. This could be done by means of automatic-controlled motors and by switching off the systems temporarily. German machine-tool manufacturers have already taken steps in this direction. At the EMO trade fair in Milan this October they exhibited energy-efficient motors with an integrated energy recovery system, as well as customized solutions for turning on and turning off individual machine components and for the systematic monitoring of energy consumption.
The Fraunhofer IWU plans to pursue and develop approaches like these. The institute is intent on becoming a "research factory for resource-efficient production." Production equipment and technologies for power trains and body construction of motor vehicles with very low material and energy inputs will be tested there in the coming years. The Chemnitz researchers, for instance, want to replace standard welding procedures in assembly operations with mechanical joining processes such as clinching and riveting. "Alternative methods such as these enable comparable joint strengths to be achieved with lower energy inputs," explains Sterzing.
The research factory's production facilities will be monitoried by a total energy management system so that lost energy can be tracked down and reused where appropriate. Remaining energy losses could be offset by renewable energy sources in order to cut back CO2 emissions. An important part of the research factory is the "Excellence Center for Automobile Production," founded jointly by IWU and Volkswagen. The innovation alliance "Green Carbody Technologies," coordinated by IWU, is also out to achieve more energy efficiency. VW has teamed up with 50 manufacturing suppliers with the aim of reducing by up to 50 percent the energy input required to produce and paint a car body.
Germany is already a world leader in developing energy efficiency technologies, alongside the United States and Japan. That's the conclusion of a study conducted by the Federal Environment Agency. With a market share of 18 percent in the international trade of energy-efficient goods, a market with a bright future, Germany even has a significant lead ahead of the United States, Italy and Japan. In their efforts to tap this global market, German enterprises are supported by the "Energy Efficiency Export Initiative," organized by the BMWi. The initiative sponsors information events about various foreign markets as well as business trips. It even includes buyer trips to Germany, giving managers of foreign enterprises the opportunity to tour German manufacturers of energy efficiency technology.
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