Research Cluster – Sustainable Power Systems


The focus of this interdisciplinary research cluster “Sustainable Power Systems” is the scientific steering of a transition, which transforms the currently centralized electrical grid in Germany to an age of renewable energies with predominantly decentralized grid structures. Within the following years new technical solutions must be found which ensure a reliable electrical energy supply. This solutions should be economically worthwhile and sustainable.


Sustainable energy supply may be expected to save resources with limited ranges like coal or natural gas for use by future generations. It should not be possible to block the access to energy resources by political dependencies. Another aspect of sustainability is climate protection. Further environmental pollution shall be avoided. In this sense the efficiency of the energy system represents a key role.

In Germany the Renewable Energy Law claims therefore that the share of renewable energies in electricity generation shall rise from 17 % today to 35 % in 2020 and continuously afterwards. With the energy transition process (“Energiewende”), which the German Federal Government enacted in 2011, the goal is a power supply predominantly by renewable sources. It is not possible to perform such a complex development by simply substituting all conventional power plants by renewable ones. You have to solve several problems then. Things become more complicate, because these are the big power stations which are switched off during the energy transition process.

To clarify these outstanding questions the three departments of Electrical Engineering, Mechanical Engineering and Economics and Social Sciences of the Helmut-Schmidt-University founded a cross-disciplinary research cluster “Sustainable Power Systems, which focuses a wide range of expertise on this subject area. By means of coordinated individual projects it is analyzed, how the technical transition process from a central power grid structure to an optimized integration of renewable energies can be accomplished. Necessary modifications and innovations have to be performed, e.g. concepts for using energy storage and smart grids. Solutions for problems that appear in this process are worked out multidisciplinary.

Starting Position of Electrical Power Supply in Germany

The Act on the Sale of Electricity to the Grid of year 1990 formed the legal basis for the power input with renewable energies in Germany. The use of renewable energies increased by more than 30 % per year since then. In 2000 this law was substituted by the more developed Renewable Energy Law, which was amended in 2004, 2008, 2011 and 2012.

Intended purpose of this law is to reduce the economic cost of energy supply including long term external effects, to spare fossil energy resources and promote  enhancements of technologies for power generation with renewable energies. This should be done to make possible a sustainable power supply on behalf of climatic and environmental protection. The law regulates the preferential grid connection of plants for power generation with renewable energy sources as well as the preferable take-up, transfer, distribution and fees for this electricity by grid operators.

Further, an energy transition process was enacted by the German Federal Government in 2011. The goal of this action is to switch off all nuclear power plants until 2022. Suitable alternatives must be found for these generally big plants, primarily on the basis of renewable energies.  Also the grids must be extended and adapted to the altered circumstances. To ensure that this required grid extension is accomplished contemporarily, the Energy Line Extension Act was modified in 2011. Thus the time from planning to completion of new lines is shortened from ten to four years.

With this energy transition process the German Federal Government intends to enter an age of renewable energies. According to the Renewable Energy Law of year 2012 the minimal amount of renewable energies in electricity generation shall be 35 % until 2020, 40 % until 2030, 65 % until 2040 and 80 % until 2050. Simultaneously the gross final energy consumption in Germany shall be satisfied with at least 18 % renewable energies. There is the requirement that this extension of the use of renewable energies is arranged consequently, ambitiously, sustainable and efficiently. Due to the partially high volatility of renewable energies such a transition to a predominantly renewable electricity generation is not possible without adequate energy storage which can store a sufficient energy quantity for periods of 1-2 weeks.

Climate protection is not the primary benefit when using renewable energies, because the emission of greenhouse gases can be reduced essentially cheaper by different means. However, renewable energies have also a share in the reduction of other pollutant emissions such as SO2 or NOx. In particular, with these energy sources we can look ahead for future times when global rivalry on finite reserves of fossil fuels grows and international conflicts hamper or prohibit the access to these sources. Solely the fear of shortenings could cause price rises.  Not least it’s a case of industrial politics. Those companies and states, who develop products and structures today, will be the market leaders tomorrow.

The topic “Renewable Energies” should not be discussed isolatedly. It should always be regarded in the context of a more efficient use of energy. Scientific studies and praxis show again and again that an economic use of energy is often cheaper than its commercial allocation. Though concerning to this matter a lot has been done in the recent past, especially in industries, there is considerable room for improvements. Also shoulod renewable energies always be used in union with energetic optimisations.


With the extension of renewable primary energy carriers a decentralized electricity supply  at minimal cost shall be realized in Germany. Though fossil power plants must support  the regenerative power plants within a transition period.

In the past different types of regenerative power supplies in a wide power range could be combined within a short period of time. Additionally fossil technologies were enhanced such that a reduction of their specific power per unit resulted in better efficiency factors.

At present there exist two technologies for electrical power supply, which complement one another more or less, dependent on the local circumstances. In certain areas, where generation and consumption of electrical energy and heat correspond with one another approximately, increasingly self-sustaining structures arise. In other areas a grid connected supply is essential, which must be controlled by an intelligently actuated load flow with minimal losses. Both these technologies must be networked and ensure an energy allocation tailored to suit the market need. Especially in the first case methods and strategies for energy storage as well as for load monitoring are necessary.

In the research cluster “Sustainable Power Systems” we analyze with a holistic approach the particular scientific shortcomings with respect to a flexible and sustainable energy supply. Approaches for solutions that can be realized with present as well as future technology are pointed out. Key technologies are evaluated in more detail and the basics are provided to achieve an in-depth understanding of an efficient energy allocation and an efficient energy consumption in public. An optimal master strategy must be worked out under consideration of chances and limits of the particular technologies. Significant aspects are the security of energy supply, an efficient use of resources, the reduction of carbon dioxide emissions, sustainability and a wider consumer acceptance. Further the cost-effectiveness has to be considered.

In addition to the technical view historical experiences with solutions in power engineering are evaluated. In this way the used technologies of energy storage, energy conversion and energy consumption are valued to draw conclusions for the specific application of an international networked society and to present sociopolitical aspects taking into account the international networking.

As a result the technological and sociopolitical cornerstones to ensure a high security of energy supply are worked out while simultaneously reaching high ecological aims under consideration of ecological circumstances.  The successful implementation of this strategy together with a public understanding of energy technology contributes to a contemporary entrance into the renewable age and gives the German economy an essential advantage.

Shortcoming Analysis

The transition from a centralized electricity supply with fossil-fueled large-scale power plants and nuclear power plants to a decentralized and sustainable energy supply is forced by rising fuel prices, shrinking resources, minimization of greenhouse gas emissions and political demands. Consequential technical and social requirements should be realized initially until 2020. However, up to now there are no conclusive concepts for a predominantly decentralized, regenerative energy supply tailored to suit the market need.

To make matters worse, the energy mix of the German electricity supply must get along without nuclear power starting with 2022. Moreover, up to 2020 the German power grids shall be fed with 35 % renewable energies and the total final energy consumption shall have a share of 18 % of renewables. Until 2050 the portion of regenerative power feeding shall rise to 80 %. However, renewable energies like wind are volatile. As a consequence the need for short-, medium- and long-time storage as well as strategies for an intelligent use of electric energy  increases. At present the storage technologies and the required amount of storage are not sufficiently cleared. Corresponding with these needs are the strategies for storage management that have to be developed.

A primary shortcoming is the fact that holistic and environmentally friendly concepts for the transition period to a predominantly regenerative power generation as well as for the period of an approximately full supply with renewables do hardly exist. The same is true for technologies in question, smart distribution and smart controlling of effective energy.

The technical evolution, especially the transition from using fossil and nuclear fuels to a sustainable energy sector is in the first place a social process with social actors. This construction is embedded in social structures, therefore impacts of the technical evolution must be recognized early. Driven by different actors with different interests and power potentials the evolution goes on in different structured parts of the society. In each of these parts technology is developed with other orientations. Without consideration of the technological genesis process a consequent restructuring of an established but expiring technology cannot be performed consistently. The necessary understanding of the ongoing processes becomes more difficult because of the increasing speed of technical innovations, the technical design by organized interests and cultural visions and the diversity of technification processes which make impacts inside a system and between coupled system more complex.

Additionally must be considered that theoretical energy savings by improvements in efficiency can be realized only partly or not at all. This problem is known as rebound effect. Under some circumstances an efficiency improvement can even increase consumption. Because rebound effects are multifaceted and act only very indirectly, it is difficult to capture them.

A technical-political and ecological development of competencies must stimulate reflections on alternatives in construction, implementation and application of technology. It can only be applied, if also a wide sensitization for resources saving technical design and a quickest possible substitution of fossil and nuclear fuels, energy saving and consequent use of renewable energies can be achieved.

Research in energy conversion as well as use and storage of energy had always special focuses of the particular user’s point of view or of the studied application. Even from a technical point of view holistic solutions were not a focus.  Historical treatments, social-political aspects and juridical analyzes were considered only if mandatory. The described approach of the research cluster “Sustainable Power Systems” will collect all aspects, which exist as individual components or will be developed, with holistic analyzes. Further, approaches for optimized solutions for an efficient energy conversion, use of energy and storage are worked out that open a door into an age of renewable energies.

Scientific Approach

The vision of the research cluster “Sustainable Power Systems” is worked out in several single steps. Some of these step allow parallel treatment, others are consecutive. At first a fundamental and holistic analysis must be performed with a complete simulation of a decentralized power supply.For this purpose a dynamic grid model with 100 % renewable energies will be established. Crucial factors are grid support and smart controlling by means of storage and determined load management.

Also current and potential future storage technologies as well as social-political boundary conditions are considered. This requires an interdisciplinary cooperation of engineering sciences, but in some aspects also of economics and social sciences. Besides the control system it shall be evaluated, which basic contributions to grid support are possible by smart controlled large-scale consumers like smelting furnaces or cold storage houses. On the other hand storage capabilities and energy efficiency of renewable energy sources must be researched fundamentally and scientifically. In this way the potentials of an efficient renewable power supply is shown. Examples are artificial dam lakes or the efficiency factor of energy converting parts of wind turbines. At the same time actual energy conversion technologies like jet-engines and fuel-cells are analyzed and optimized.


A sustainable power supply must ensure that highly toxic substances like dioxins and furans are efficiently removed from the exhaust gases. These substances can also occur in the combustion of renewable sources. Even highly efficient energy converters like fuel cells must be fed with gases of well-defined compounding. This is true especially for renewable sources, when sulfurous gas components must be removed.

Experience shows that energy efficiency often caused an increase of resources in the past instead of savings. This so called rebound effect has a significant impact on the fundamental evaluation of an efficient power supply and must be taken into account. The development of a believed environment-friendly technology can be shown with the example of a sterling motor. It presents insights to the process of technical genesis influenced by technical and economic difficulties, macroeconomic changes, increasing ecological problems, social debates as well as political and legislative boundary conditions.

A wide acceptance for a sustainable power supply can only be achieved by intensive public relation. With a closer look on classic vocational training concepts and programmatics for advanced vocational trainings (Eckert 2003) it can be shown that there have been thoughts on human, ecological oriented and mild techologies already since industrialization in context with cultural criticism an industrial social policy. On the basis of these experiences in history a second step must clarify, how the required change in outlook can be obtained that the use of renewable energies in the power supply is essential. This has to be done with the background of the transformative social-learning theory (Ed. O’Sullivan et al. 2002, 2004) and the acquisition of technological competence (Negt 1998) and the ability to judge. Thus the well-known discrepancy between environmental awareness and environmental behavior can be decreased.

With a consecutive step based on the resulting findings the developed model can be validated under laboratory conditions. For that matter different  energy converters, energy storage and several concepts for electrical power transmission are considered. To ensure the grid stability, the security of supply and the public acceptance socio-scientific analyses and predictions will accompany  the model validation.


Renewable energies need new technics and concepts in order to be used efficiently. While electricity was generated in few large-scale power plants up to now, there will be also an increasing number of smaller power producers in future feeding decentralized all over the grid. Such a decentralized power generation makes great demands on the regenerative electricity generators. The reason is that from a certain size on the same rules apply as for conventional power plants.

A generation unit, which is connected to the grid, must fulfil special requirements for

  • active power feeding
  • frequency stability
  • supply of reactive power
  • voltage stability
  • behavior at voltage drops after short-circuits
  • voltage quality


Beyond that it must be clarified for which amounts of energy transmission the grid has to be dimensioned. Problems arise, because significant amounts of renewable energies are fed in at the coastline, while the centers of the loads are situated in the south and west of Germany. A research is necessary to identify, at which points of the grid which kinds of extension measure are meaningful and which locations need energy storage.

An efficient energy management needs lots of current data, which must be captured in suitable form, compressed, transmitted and evaluated. For this monitoring suitable sensors, reliable and powerful communication networks and common interfaces are required. In case of a communication fault the system must work safely anyway. Approaches for a solution base upon distributed intelligence.

Such smart grids are required for an intelligent grid controlling, which includes control of feeding and consumption. It has to be examined, how existing grid structures can be enhanced to this level of technology in a cheap and efficient way.


Letzte Änderung: 13. May 2019