Dr. Mirko Schäfer

2022

• Qussous R, Harder N, Schäfer M, Weidlich A
  Increasing the realism of electricity market modeling through market interrelations
  2022 Proceedings of the 1st International Workshop on Open Source Modelling and Simulation of Energy Systems, Seiten: 1 - 6
  
   
  Datei herunterladen
• Weidlich A, Schäfer M
  Mind the Gap – Abstände von Strom- zu Brennstoffpreisen und ihr Einfluss auf die Elektrifizierung von Wärme und Mobilität
  2022 ifo Schnelldienst, Band: 12, Seiten: 18 - 21
• Unnewehr JF, Weidlich A, Gfüllner L, Schäfer M
  Open-data based carbon emission intensity signals for electricity generation in European countries - top down vs. bottom up approach
  2022 Cleaner Energy Systems, Band: 3, Nummer: 100018, Seiten: 1 - 13
• Weidlich A, Neumann D, Gust G, Staudt P, Schäfer M
  Proceedings of the 11th DACH+ Conference on Energy Informatics
  2022 SpringerOpen
• Unnewehr J, Schäfer M, Weidlich A
  The value of network resolution – A validation study of the European energy system model PyPSA-Eur
  2022 Proceedings of the 1st International Workshop on Open Source Modelling and Simulation of Energy Systems, Seiten: 1 - 7
  
   
  Datei herunterladen

2021

• Weidlich A, Neumann D, Gust G, Staudt P, Schäfer M
  Proceedings of the 10th DACH+ Conference on Energy Informatics
  2021 SpringerOpen

2020

• Schäfer M, Tranberg B, Greiner M
  Power flows in complex renewable energy networks
  In: Discoveries at the Frontiers of Science
  2020, Springer, Seiten: 239 - 251,
• Schäfer M, Tranberg B, Jones D, Weidlich A
  Tracing carbon dioxide emissions in the European electricity markets
  2020 Proceedings of the 17th European Energy Market Conference, Seiten: 1 - 6
  » Kurzfassung anzeigen« Kurzfassung verbergen
  Kurzfassung

  Consumption-based carbon emission measures aim to account for emissions associated with power transmission from distant regions, as opposed to measures which only consider local power generation. Outlining key differences between two different methodological variants of this approach, we report results on consumption-based emission intensities of power generation for European countries from 2016 to 2019. We find that in particular for well connected smaller countries, the consideration of imports has a significant impact on the attributed emissions. For these countries, implicit methodological choices in the input-output model are reflected in both hourly and average yearly emission measures.
  
  
   
  Datei herunterladen

2019

• Abdel-Khalek H, Schäfer M, Vásquez Torres RA, Unnewehr J, Weidlich A
  Forecasting Cross-Border Power Transmission Capacities in Central Western Europe Using Artificial Neural Networks
  2019 Energy Informatics, Band: 2, Ergänzungsband: 1, Seiten: 1 - 13
  
   
  Datei herunterladen
• Schäfer M, Hofmann F, Abdel-Khalek H, Weidlich A
  Principal Cross-Border Flow Patterns in the European Electricity Markets
  2019 16th International Conference on the European Energy Market
  
   
  Datei herunterladen
• Brown T, Schäfer M, Greiner M
  Sectoral Interactions as Carbon Dioxide Emissions Approach Zero in a Highly-Renewable European Energy System
  2019 Energies, Band: 12, Seite: 1032
  » Kurzfassung anzeigen« Kurzfassung verbergen
  Kurzfassung

  Measures to reduce carbon dioxide emissions are often considered separately, in terms of electricity, heating, transport, and industry. This can lead to the measures being prioritised in the wrong sectors, and neglects interactions between the sectors. In addition, studies often focus on specific greenhouse gas reduction targets, despite the uncertainty regarding what targets are desirable and when. In this paper, these issues are examined for the period after 2030 in an existing openly-available, hourly-resolved, per-country, and highly-renewable model of the European energy system, PyPSA-Eur-Sec-30, that includes electricity, land transport, and space and water heating. A parameter sweep of different reduction targets for direct carbon dioxide emissions is performed, ranging from no target down to zero direct emissions. The composition of system investments, the interactions between the energy sectors, shadow prices, and the market values of the system components are analysed as the carbon dioxide limit changes. Electricity and land transport are defossilised first, while the reduction of emissions in space and water heating is delayed by the expense of new components and the difficulty of supplying heat during cold spells with low wind and solar power generation. For deep carbon dioxide reduction, power-to-gas changes the system dynamics by reducing curtailment and increasing the market values of wind and solar power. Using this model setup, cost projections for 2030, and optimal cross-border transmission, the costs of a zero-direct-emission system in these sectors are marginally cheaper than today’s system, even before the health and environmental benefits are taken into account.
  
  
   
  Datei herunterladen

2018

• Schlachtberger D, Brown T, Schäfer M, Schramm S, Greiner M
  Cost optimal scenarios of a future highly renewable European electricity system: Exploring the influence of weather data, cost parameters and policy constraints
  2018 Energy, Band: 163, Seiten: 100 - 114
  » Kurzfassung anzeigen« Kurzfassung verbergen
  Kurzfassung

  Cost optimal scenarios derived from models of a highly renewable electricity system depend on the specific input data, cost assumptions and system constraints. Here this influence is studied using a techno-economic optimisation model for a networked system of 30 European countries, taking into account the capacity investment and operation of wind, solar, hydroelectricity, natural gas power gen- eration, transmission, and different storage options. A considerable robustness of total system costs to the input weather data and to moderate changes in the cost assumptions is observed. Flat directions in the optimisation landscape around cost-optimal configurations often allow system planners to choose between different technology options without a significant increase in total costs, for instance by replacing onshore with offshore wind power capacity in case of public acceptance issues. Exploring a range of carbon dioxide emission limits shows that for scenarios with moderate transmission expansion, a reduction of around 57% compared to 1990 levels is already cost optimal. For stricter carbon dioxide limits, power generated from gas turbines is at first replaced by generation from increasing renewable capacities. Non-hydro storage capacities are only built for low-emission scenarios, in order to provide the necessary flexibility to meet peaks in the residual load.
  
  
   
  PDF-Datei herunterladen
• Hörsch J, Schäfer M, Becker S, Schramm S, Greiner M
  Flow tracing as a tool set for the analysis of networked large-scale renewable electricity systems
  2018 Int J Elec Power, Band: 96, Seiten: 390 - 397
  » Kurzfassung anzeigen« Kurzfassung verbergen
  Kurzfassung

  The method of flow tracing follows the power flow from net-generating sources through the network to the net-consuming sinks, which allows to assign the usage of the underlying transmission infrastructure to the system participants. This article presents a reformulation that is applicable to arbitrary compositions of inflow appearing naturally in models of large-scale electricity systems with a high share of renewable power generation. We propose an application which allows to associate power flows on the grid to specific regions or generation technologies, and emphasizes the capability of this technique to disentangle the spatio-temporal patterns of physical imports and exports occurring in such systems. The analytical potential of this method is showcased for a scenario based on the IEEE 118 bus network.
• Tranberg B, Schäfer M, Brown T, Hörsch J, Greiner M
  Flow-based analysis of storage usage in a low-carbon European electricity scenario
  2018 15th International Conference on the European Energy Market (EEM), 2018
  
   
  PDF-Datei herunterladen
• Tranberg B, Schwenk-Nebbe LJ, Schäfer M, Hörsch J, Greiner M
  Flow-based nodal cost allocation in a heterogeneous highly renewable European electricity network
  2018 Energy, Band: 150, Seiten: 122 - 133
  » Kurzfassung anzeigen« Kurzfassung verbergen
  Kurzfassung

  For a cost efficient design of a future renewable European electricity system, the placement of renewable generation capacity will seek to exploit locations with good resource quality, that is for instance onshore wind in countries bordering the North Sea and solar PV in South European countries. Regions with less favorable renewable generation conditions benefit from this remote capacity by importing the respective electricity as power flows through the transmission grid. The resulting intricate pattern of imports and exports represents a challenge for the analysis of system costs on the level of individual countries. Using a tracing technique, we introduce flow-based nodal levelized costs of electricity (LCOE) which allow to incorporate capital and operational costs associated with the usage of generation capacity located outside the respective country under consideration. This concept and a complementary allocation of transmission infrastructure costs is applied to a simplified model of an interconnected highly renewable European electricity system. We observe that cooperation between the European countries in a heterogeneous system layout does not only reduce the system-wide LCOE, but also the flow-based nodal LCOEs for every country individually.
• Hofmann F, Schäfer M, Brown T, Hörsch J, Schramm S, Greiner M
  Principal Flow Patterns across renewable electricity networks
  Epl-europhys Lett, Band: 124, Seite: 18005, 2018

2017

• Schäfer M, Schwenk-Nebbe LJ, Hörsch J, Tranberg B, Greiner M
  Allocation of nodal costs in heterogeneous highly renewable European electricity networks
  2017 14th International Conference on the European Energy Market (EEM), 2017, Seiten: 1 - 6
  » Kurzfassung anzeigen« Kurzfassung verbergen
  Kurzfassung

  We consider a simplified model of a future European electricity network with a high share of renewable generation. In a cost optimal design of such a system, most of the renewable generation capacity is placed at locations with favorable weather conditions, that is for instance onshore wind in countries bordering the North Sea and solar PV in South European countries. Countries with less favorable renewable generation conditions benefit from this capacity by importing the respective electricity as power flows through the transmission grid. Using flow tracing techniques, we disentangle the emerging pattern of imports and exports and assign shares of the distributed generation capacity in the European system to the countries which actually make use of them. This procedure yields nodal levelized costs, which incorporate both internal and external generation costs associated with the electricity consumption in a country.
• Schäfer M, Tranberg B, Hempel S, Schramm S, Greiner M
  Decompositions of injection patterns for nodal flow allocation in renewable electricity networks
  2017 Eur Phys J B, Band: 90, Seite: 144
  » Kurzfassung anzeigen« Kurzfassung verbergen
  Kurzfassung

  The large-scale integration of fluctuating renewable power generation represents a challenge to the technical and economical design of a sustainable future electricity system. In this context, the increasing significance of long-range power transmission calls for innovative methods to understand the emerging complex flow patterns and to integrate price signals about the respective infrastructure needs into the energy market design. We introduce a decomposition method of injection patterns. Contrary to standard flow tracing approaches, it provides nodal allocations of link flows and costs in electricity networks by decomposing the network injection pattern into market-inspired elementary import/export building blocks. We apply the new approach to a simplified data-driven model of a European electricity grid with a high share of renewable wind and solar power generation.
• Schramm S, Schäfer M
  New Horizons in Fundamental Physics
  2017 Springer International Publishing
• Schäfer M, Hempel S, Tranberg B, Hörsch J, Schramm S, Greiner M
  Power Flow Tracing in Complex Networks
  In: New Horizons in Fundamental Physics
  2017, Springer International Publishing, Seiten: 357 - 373,
  » Kurzfassung anzeigen« Kurzfassung verbergen
  Kurzfassung

  The increasing share of decentralized renewable power generation represents a challenge to the current and future energy system. Providing a geographical smoothing effect, long-range power transmission plays a key role for the system integration of these fluctuating resources. However, the build-up and operation of the necessary network infrastructure incur costs which have to be allocated to the users of the system. Flow tracing techniques, which attribute the power flow on a transmission line to the geographical location of its generation and consumption, represent a valuable tool set to design fair usage and thus cost allocation schemes for transmission investments. In this article, we introduce a general formulation of the flow tracing method and apply it to a simplified model of a highly renewable European electricity system. We review a statistical usage measure which allows to integrate network usage information for longer time series, and illustrate this measure using an analytical test case.
• Schäfer M, Bugge Siggaard S, Zhu K, Risager Poulsen C, Greiner M
  Scaling of transmission capacities in coarse-grained renewable electricity networks
  2017 Epl-europhys Lett, Band: 119, Seite: 38004
  » Kurzfassung anzeigen« Kurzfassung verbergen
  Kurzfassung

  Network models of large-scale electricity systems feature only a limited spatial resolution, either due to lack of data or in order to reduce the complexity of the problem with respect to numerical calculations. In such cases, both the network topology, the load and the generation patterns below a given spatial scale are aggregated into representative nodes. This coarse-graining affects power flows and thus the resulting transmission needs of the system. We derive analytical scaling laws for measures of network transmission capacity and cost in coarse-grained renewable electricity networks. For the cost measure only a very weak scaling with the spatial resolution of the system is found. The analytical results are shown to describe the scaling of the transmission infrastructure measures for a simplified, but data-driven and spatially detailed model of the European electricity system with a high share of fluctuating renewable generation.

2015

• Tranberg B, Thomsen AB, Rodriguez RA, Andresen GB, Schäfer M, Greiner M
  Power flow tracing in a simplified highly renewable European electricity network
  2015 New J Phys, Band: 17, Seite: 105002
  » Kurzfassung anzeigen« Kurzfassung verbergen
  Kurzfassung

  The increasing transmission capacity needs in a future energy system raise the question of how associated costs should be allocated to the users of a strengthened power grid. In contrast to straightforward oversimplified methods, a flow tracing based approach provides a fair and consistent nodal usage and thus cost assignment of transmission investments. This technique follows the power flow through the network and assigns the link capacity usage to the respective sources or sinks using a diffusion-like process, thus taking into account the underlying network structure and injection pattern. As a showcase, we apply power flow tracing to a simplified model of the European electricity grid with a high share of renewable wind and solar power generation, based on long-term weather and load data with an hourly temporal resolution.

2008

• Heide D, Schäfer M, Greiner M
  Robustness of networks against fluctuation-induced cascading failures.
  2008 Phys Rev E, Band: 77, Nummer: 5 Pt 2, Seiten: 056103 - 056103
  » Kurzfassung anzeigen« Kurzfassung verbergen
  Kurzfassung

  Fluctuating fluxes on a complex network lead to load fluctuations at the vertices, which may cause them to become overloaded and to induce a cascading failure. A characterization of the one-point load fluctuations is presented, revealing their dependence on the nature of the flux fluctuations and on the underlying network structure. Based on these findings, an alternate robustness layout of the network is proposed. Taking load correlations between the vertices into account, an analytical prediction of the probability for the network to remain fully efficient is confirmed by simulations. Compared to previously proposed mean-flux layouts, the alternate layout comes with significantly less investment costs in the high-confidence limit.

2006

• Schäfer M, Scholz J, Greiner M
  Proactive robustness control of heterogeneously loaded networks.
  2006 Phys Rev Lett, Band: 96, Nummer: 10, Seite: 108701
  » Kurzfassung anzeigen« Kurzfassung verbergen
  Kurzfassung

  A proactive measure to increase the robustness of heterogeneously loaded networks against cascades of overload failures is proposed. It is based on load-dependent weights. Compared to simple hop weights, respective shortest flow paths turn a previously heterogeneous load distribution into a more homogeneous one for the nodes and links of the network. The use of these flow paths increases the networks robustness and at the same time reduces the investment costs into the networks capacity layout. These findings are of relevance for critical infrastructures like communication and transportation networks.