Interview with

Dr. Arndt Schweigert

Head of Power Generation sector management, Schaeffler Group IndustrialHerzogenaurach,

"The technologies to produce energy in the sea are now on the stand as the wind generation 25 years."

Still a relatively small, but very fine and interesting, especially the Schaeffler Group's Power Generation sector management. While you're in the wind already come of age, you feel especially in some areas of hydropower to set back decades. Besides the established technique, there are many promising technologies, projects and prototypes, of which some will emerge as sustainable. development scout spoke with Dr. Arndt Schweigert about the challenges facing the renewable energy in the Schaeffler Group.

The first question:

development scout: There are many technologies for energy production from hydropower. What are the most important?

Dr. Schweigert: Basically, the water power the advantage of a flexible energy supply and takes a share of about fifteen percent of global electricity production a high priority. For centralized power supply dams pose as so-called large hydropower represents an important area during the dam potentials in Europe for nearly two-thirds are already developed, they are in the Asian countries still be intensified. This is necessary because there is still a huge demand for energy cover.

The so-called small-scale hydro is defined as in Europe in the range of up to 10 MW, in Asia it is called 20 to 30 MW. The principles are partly similar to the large hydroelectric dimensioned only in a smaller package. Moreover, in countries with a low central energy supply, such as India or China the ability to provide local energy supply cities, towns and industrial areas. This happens, for example, with conventional water wheels, known from historical hydropower, which are in the kilowatt range. Or live as old technologies such as the principle of Archimedes screws up again, which were originally designed for use with water. Returns to about its principle, the water with a gradient driving the screw, which is coupled to a generator. These so-called hydro snails can already be built with capacities up to several kW 100 and also for decentralized energy supply in Europe and more interesting.

Couplings, brakes and monitoring for the wind turbine

Energy from the sea provide current and wave power plants. It first uses the natural ocean current power generation, especially in regions where there are tides. There also have the highest potential is found in terms of energy density. The second principle is found in similar areas where the wind also ensures sufficient undulation. The waves are utilized that the mechanisms their kinetic energy is converted into electrical energy.

development scout: Schaeffler has its storage solutions greatly contributed to the project "Pelamis", which has now achieved a decisive breakthrough. What were the biggest challenges in implementing this wave energy converter?

Dr. Schweigert: The problem here is very complex. Advantageous so far is that Pelamis is not installed permanently under water, but the water surface. Of course, diving and splashing waves parts of the machine into the water, but which will be protected by appropriate seals. The waves on the other hand provide for permanent movement. Corresponding to the shaft, the bearings are constantly cycles subjected to pivotal movement, about seven, eight times per minute. Per year result in this case pivoting movements of the order of three to four million. This is a high non-comparable with other applications stress the bearings, and thus a great challenge for us. We have also combined partly larger angle of movement with a high number of oscillations per unit time. A major goal of plant engineers, it was also to design all the bearings maintenance free, ie to use lubricant-free bearings that require no maintenance and do not cause pollution. The lifetime is limited at each maintenance-free bearings. Possible replacement intervals must therefore be defined predictable. At Pelamis example, the main camp for at least five years are designed lifetime.

development scout: What role play the different locations defined by wave action, salinity, etc. for your stock?

Dr. Schweigert: In the last fifteen years, many studies have been carried out, thanks to which could emerge focus locations. In Europe, for example, there are the coasts of Britain, Ireland, Portugal, but partly also Scandinavia. For the specific design there are two basic concepts: There are to use a sealed or sealed systems that protect components against the ingress of salt water. The aim of the manufacturer is, however, bearing insert, which can operate in water. These bearings were largely maintenance-free, the risk of failure would prevent water ingress into the bearing and the risk of pollution from leaking fluids. It is therefore important to develop water-lubricated bearings for current and wave power. To these developments, we are working very hard. There is still a long way to get there, both corrosion and wear under control, particularly in terms of required number of years of life values. The different salinities not play the key role, because it only takes relatively little salt to corrosion and cause it to wear. Based on the locations of the systems, the systems are designed with regard to the flow velocities at power stations and to the height, the number per unit of time and distance of the waves in the wave-power plants.

development scout: What technologies are in your opinion the water continue to be governed?

Dr. Schweigert: That's still no telling really. The technologies for energy production in the sea are now on the stand as the wind generation 25 years. Currently there are some 80 different techniques in wave power and 40 in the field of fluid power, based partly on similar but also different principles. There are a lot of projects but also prototypes both on a smaller scale and have one to one function models. Perspective will prevail not only a principle, but it will be more dependent on the site. Various studies show that the wave energy has a higher potential than the current energy. Currently, but everything is still in the development phase.

development scout: What applications Schaeffler realized in the solar energy?

Dr. Schweigert: In solar energy, all the systems are of interest in which a movement, ie solar tracking is required. This happens especially in the concentrated photovoltaic, but especially in the larger power plants, the so-called solar thermal. Which in turn can be found mostly in the sun-rich areas such as Spain - example is the solar power plant Andasol - or Italy, Greece, California. There are uniaxial or biaxial trackers. During the rotation around the azimuth axis, the whole system follows the sun from east to west, ie rotation around the vertical axis, from sunrise to sunset. Then there are combinations which take into account in addition the height of the sun. And there are uniaxial systems that require only the elevation axis. In this case, the system pivots around the horizontal axis from east to west.

development scout: What trends do you see in the solar industry?

Dr. Schweigert: While winning for private use the classic photovoltaic systems is becoming increasingly important, it will be great for the energy due to the improved efficiency, the solar thermal power plants. Currently being built in the U.S. in the Mojave Desert, a solar thermal power plant of the parabolic trough technology, which is intended to produce in the final stage 1000 MW. Or take the Desertec project, which also for desert power especially Europe and deliver the entire Mediterranean region. The Desertec Industrial Initiative, DII want covering fifteen percent of Europe's energy needs and a substantial part of the power generation in North Africa and the Middle East by the year 2050 from this project. For us it is an important goal, to be here with this.

development scout: There are plenty of sun, but what will the regenerated energy from the desert in the future to reach the Central Europeans?

Dr. Schweigert: The low-loss power transmission is a key issue, are working hard on the. As a future task that is similar to the technology change from conventional to alternative energy. The Schaeffler Group is indirectly involved in this "Transport" involved, since the expansion of the energy networks high-voltage or medium-voltage switchgear and their drive systems are required in which our bearings can be used.

development scout: What types of bearings are used in all these applications use?

Dr. Schweigert: The plain bearings play a big role, sometimes a bigger one than that Rolling. When used in water, there are two basic fields of application and corresponding challenges. In the area of ​​flow forces, we mainly have rotational movement, for which roller bearings are actually suitable. But hydrodynamic plain bearings are also conceivable here – with the desire to use water as a medium. The wave force, on the other hand, usually generates pivoting movement and places particularly high demands on the bearings in this regard: Due to the slow speeds and the constant reversal of movement, these bearings generally run under mixed friction conditions. For this we have already had very good maintenance-free bearing materials like Elgoglide, but only on condition that the stock is tightly sealed, the system developer would naturally like water lubricated solutions. However, there is no application under these conditions for a long time tested principles for the "water lubrication". This applies primarily to for bearings but also for plain bearings. Here are, as already mentioned, the new challenges for the "Energy from the sea". In solar energy, we have a lot of bearing applications, because slow movements, sometimes high loads and tilting movements are generated. Maintenance is an essential requirement - in addition to Elgoglide are also products like ELGOTEX or metal-polymer composite material available.

development scout: Wind, water, sun, storm: How can you generally calculate components whose environmental influences are actually unpredictable, which should be maintenance-free and ideally have to last a lifetime?

Dr. Schweigert: Can calculate exactly one does not actually. One life can, under certain conditions, such as sufficient to calculate existing seals or korossionsgeschütze surfaces. For this we need a specification that defines the nature of the environment and the resulting load and movement collectives. Wherein the wave energy, for example, height, number per unit of time and distance of the waves, which cause corresponding loads and movements. In Sonnennachführsystemen play besides the required number of pivotal movements including the forces of dead weight and wind loads of the system involved. Relevant to the period of use can also environmental conditions such as dust, sand, moisture, water, and so forth. Ultimately, therefore, the theoretical calculation but still subject to the influences of the environment.

Interview by Editor in Chief Angela Scheufler.

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