Institutskolloquium des IPP 2016

Ort: Garching

Impact of renewable energy sources on electricity production

Institutskolloquium
Europe is pursuing an aggressive programme to increase its share of renewable energy source (RES). However, the integration of intermittent RES (wind and photovoltaic) in the electrical system requires either maintaining in operation thermoelectric backup systems or providing a substantial amount of electricity storage. We analyze the Italian data for the year 2013 provided by the transmission system operator TERNA. Intermittent RES power is scaled-up to a level at which it generates an amount of electricity equal to the annual demand. While a substantial reduction of the energy annually produced by backup systems (and the associated CO2 emission) with respect to the no-RES case is possible in many scenarios considered here, the backup power is generally only marginally reduced below the value in the absence of RES. The strategy proposed is based on the combination of a modest amount of storage (0.5-5TWh) and base-load power (6-15GW, to be used during the seasons of low RES production). In this way the non-RES installed power can be reduced from ~50GW to less than 15GW and could be covered by a combination of biomasses and nuclear energy without any CO2 emission. [mehr]
The axisymmetric helical field of a tokamak leads to closed unperturbed particle orbits, thus arising as one of the most viable concepts for a fusion reactor. Orbit perturbations due to either Coulomb collisions or electromagnetic potential fluctuations ultimately determine the energy and particle confinement times. Macroscopic temperature and density profiles result from the balance of external sources and of the internally produced fusion power with the transport processes due to the aforementioned mechanisms. Thereby, the numerical design of a commercially viable tokamak fusion reactor requires integration of physics tools that describe both the fast/small scale processes and the slow/macroscopic evolution of the plasma profiles and the plasma shape. To this end, nowadays, progress in the theoretical description of the transport processes allows the application of increasingly realistic theory-based models. This also implies that any modeling activity should be performed keeping into account the assumptions and potential limitations of the models that are employed. In this talk, first a description of the logical coupling of the tools is given, clarifying the underlying physics of each piece of the system, from the small to the large spatial/temporal scales. Practical applications are then shown. These are based on the ASTRA-SPIDER transport/equilibrium package developed at IPP and in collaboration with TUAP (St. Petersburg), with inclusion of additional modules for turbulence-driven transport fluxes (e.g. TGLF, from General Atomics), and impurity particle transport (STRAHL, developed at IPP). Finally, an outlook is given on the open challenges in this research activity. [mehr]
"Planung, Aufbau und Betrieb der ersten ECRH - Anlage an ASDEX Upgrade " Fritz Leuterer "Electron heat transport studies with ECRH1: stiffness and critical gradient" Francois Ryter "Control of MHD instabilities by ECRH on ASDEX Upgrade" Hartmut Zohm "Co-existence of ECRH1 and ECRH2: W accumulation and high power experiments" Jörg Stober [mehr]

Connectomics: The dense reconstruction of neuronal networks

Institutskolloquium
Brains are highly interconnected networks of millions to billions of neurons. For a century, we have not been able to map these connectivity networks. Only recently, using novel electron microscopy techniques and machine-learning based data analysis, the mapping of neuronal networks has become possible at a larger scale. This new field of connectomics is still limited by technology and requires next-generation human-machine interaction for data analysis, but it is already starting to provide exciting insights into how neuronal circuits operate in the brain. Our goal is to make connectomics a high-throughput screening technique for neuroscience, to use connectomes for discovering brain-implemented algorithms, which may inspire novel machine learning, to map the imprints of sensory experience onto neuronal networks in the brain, and to investigate connectome alterations in models of psychiatric disease. [mehr]

Direct observation of gravitational waves from the merger and inspiral of two black holes

Institutskolloquium
This talk follows the annoucement made on February 11th by the LIGO Scientific Collaboration. On September 14, 2015, we detected the gravitational waves emitted by the final few orbits and merger of two black holes. In this talk, I present the main results, as well as some of the "behind the scenes" details of the discovery and subsequent analysis. Reference: P. Abbott et al., Phys. Rev. Lett. 116, 061102, 2016. [mehr]

Wird die deutsche „Energiewende“ scheitern?

Institutskolloquium
Die Bundesregierung versucht, mit Hilfe von Solar-und Windenergie eine alternative Stromversorgung zu Kernenergie und Kohleverstromung zu schaffen. Dazu dient das „Erneuerbare-Energien-Gesetz EEG“ aus dem Jahre 2000. Hinzu kam der 2011 im Eiltempo beschlossene Ausstieg aus der Nutzung der Kernenergie. Jetzt zeigt sich, dass die „Wende“ große Risiken bei der Versorgungssicherheit, der Finanzierbarkeit, den Auswirkungen auf die wirtschaftliche Entwicklung und die soziale Gerechtigkeit birgt. Diese Wende droht an ihren Widersprüchen zu scheitern. Selbst der zuständige Bundesminister für Wirtschaft und Energie, Sigmar Gabriel, äußerte im April 2014: “Die Wahrheit ist, dass die Energiewende kurz vor dem Scheitern steht.” Im Vortrag wird versucht, die Probleme zu benennen und Lösungen zu finden. Die Energieversorgung muss dem Wohl des Ganzen dienen und dem Industriestandort Deutschland nutzen. Ein Blackout wäre eine Katastrophe für das ganze Land, er muss unter allen Umständen vermieden werden. Der Vortragende ist Autor des Buches „Risiko Energiewende - Wege aus der Sackgasse“, Springer Verlag 2015. [mehr]

Efficient CO2 reduction in microwave plasma via vibrational excitation

IPP Kolloquium: Institutskolloquium
Sustainable energy generation by means of wind or from solar radiation through photovoltaics or concentrated solar power will be a significant part of the energy mix in 2025. Intermittency (due to e.g. day/night cycle) as well as regional variation of these energy sources requires means to store and transport energy on a large scale. A promising option is creating artificial solar fuels (or CO2 neutral fuels) with sustainable energy, which can easily be deployed within the present infrastructure for conventional fossil fuels. A candidate raw material would be CO2 itself (fitting in carbon capture and utilization, CCU, strategies). Presently, no efficient schemes are yet available for the conversion of CO2 into fuels. A plasma chemical approach potentially offers high energy efficiency (up to 90%) due to selectivity in the reaction processes that can be tailored via its inherently strong out-of-equilibrium processing conditions. At the same time, it is characterized by efficient and fast power switching, low investment costs, no scarce materials required, and high power density, which are all advantageous for addressing intermittency. In this presentation, the plasma chemical approach will be introduced and examples will be discussed of research carried out at the DIFFER to ultimately enable a scale up to industrial applications. In particular, a common microwave reactor approach is evaluated experimentally with Rayleigh scattering and Fourier transform infrared spectroscopy to assess gas temperatures (up to ~3000 K) and conversion degrees (up to 30%), respectively. The results are interpreted on basis of estimates of the plasma dynamics obtained with electron energy distribution functions calculated with a Boltzmann solver. It indicates that the intrinsic electron energies are higher than is favorable for preferential vibrational excitation due to dissociative excitation, which causes thermodynamic equilibrium chemistry still to dominate the initial experiments. Pulsing the power is shown to decrease gas temperatures and improve efficiency. Novel reactor approaches are proposed to tailor the plasma dynamics to achieve the non-equilibrium in which vibrational excitation is dominant. [mehr]
Eine der Kernfragen der Sozialwissenschaften besteht in der Erklärung der ungeheuren wirtschaftlichen Dynamik, die sich seit dem Beginn der Industrialisierung im späten 18. Jahrhundert entfaltet. In meinem Vortrag zeige ich, dass die Orientierung an einer als offen aber auch mit Risiken behafteten Zukunft ein wichtiger Aspekt der Dynamik des Kapitalismus ist. Anhand von Innovationsprojekten und Beispielen aus anderen Bereichen wirtschaftlichen Handelns verdeutlicht der Vortrag, welche Rolle imaginierte Zukünfte für wirtschaftliches Wachstum aber auch für wirtschaftliche Krisen spielen. [mehr]
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