Modern life is unthinkable without reliable supply of energy. Fossil fuels – oil, natural gas and coal – have been our main source of supply for a long time. Their reserves are not only limited, but through their burning, they are also primarily responsible for global climate change. Regenerative or renewable resources such as biomass, wind, sun and water are therefore increasingly used to ensure sustainable energy supply. However, the production of renewable energy depends on the weather and other factors, while the demand for energy depends on economic and social developments. The second research focus of the Sustainability Center Freiburg – "Energy Systems" – therefore is looking for ways to align the supply of and demand for energy from renewable sources. To this purpose, technologies for efficient energy conversion, storage and use are developed, and possible solutions are sought how the energy supply infrastructure can meet the complex challenges of the future.
Analysis of physical, chemical, and biological properties of energy systems
With the so-called "Energiewende" (energy transition), our energy systems change- particularly regarding the power supply. The system, which has been centralized and scarce in information for a long time, is changing into a decentralized, complex and highly dynamic power system with comprehensive information exchange. More specifically formulated: While previously few large power stations were solely responsible for the energy supply of entire regions, today, many small photovoltaic facilities and other facilities powered by wind and water feed into a grid that is varying depending on weather conditions. The management of such a complex network requires a new systemic approach.
Multifunctional system architectures are becoming a priority in research. Analytical methods of complex systems allow the increasingly microscopic investigation of dynamic, chemical and biological processes. This methodology is utilized for the regulation of energy systems.
Fundamentals for the utilization of natural resources
The biofuels used today are often not produced sustainably. They are based on the cultivation of corn, oil palm or sugarcane, mostly on large areas of monoculture, and lead to surface damage, groundwater lowering and to large-scale destruction of natural forests. Therefore, concepts are studied that aspire to a sustainable use of carbon sources. These include bio-electrochemical systems for generating electricity from wastewater using microbial fuel cells, the targeted control of novel fermentation and biosynthetic processes or biofuels, which are produced with the help of algae from carbon dioxide in seawater.
Scalability and stability of power systems
In order to make energy systems sustainable, they must first be specifically designed for scales that are optimized in their function and requirements. This way, it is possible to measure and assess their long-term costs as well as their integration into the technological and socioeconomic environment. This in turn is only possible if their network stability and network structure are known. To this end, mathematical and physical theories of highly dynamic feedback systems are developed further.
System solutions for the supply and utilization of energy
Regarding this research issue, sustainable and intelligent system solutions are developed and optimized for different applications. The spectrum ranges from microsystems over Smart Cities - i.e. the control of urban (energy) systems using digital technologies - up to national and global energy networks. We will take into consideration not only the flow of electric currents but also heat and mass fluxes. The resulting data will finally be linked to those of stationary energy producers and consumers as well as with information from the transport sector.
Technologies and components for energy conversion
By no means, all options for the sustainable supply of energy have already been explored. For example, photovoltaic technology is continually evolving, solar cells and entire modules are becoming more efficient and durable. Other technologies and specific applications are still being explored. For example, "Micro Energy Harvesting", with which small amounts of electrical energy - for example from ambient temperature or air currents - will be utilized for low power mobile devices. Also, inductive methods for the electromagnetic transmission of energy or waste heat power generation are developed further in this field of research. Finally, we are talking about components for system integration of sustainable energy systems, particularly in order to provide efficient power electronics.
Technologies for energy storage
The more diverse and time-varying the generation of energy is, the more necessary the storage technologies for electricity, heat and gas are becoming. In addition to the development of classical battery technologies in terms of energy density, durability, safety and recyclability, novel storage technologies are also researched and developed. One example is the conversion of electrical energy into chemical energy and energy storage in substances such as hydrogen, for example by photocatalytic water decomposition.