arXiv subjects

Mirko Schäfer

Publications and source records attributed to Mirko Schäfer.

18 recordsLinked to original sources

arXiv2026

Identifying demand-side measures that matter most for Europe's decarbonisation

European countries pursue a miscellany of historic, emerging, and planned initiatives to transform energy demand through behavioural shifts and end-use efficiency improvements. Yet, these efforts often evolve within fragmented national frameworks that overlook the rapidly evolving supply landscape, risking misaligned investments and diminishing public engagement. We address this need for prioritization by employing a high-resolution model of the European energy system under a net-zero constraint to co-optimise demand and supply strategies across seven sectors, mapping system response to demand mechanisms that reflect real-world practices. Our findings confirm large-scale gains from demand reductions in heating and industry, and show carbon capture reliance is most sensitive to demand reduction in aviation and shipping sectors. For heating, reducing demand peak hours yields the greatest system-level benefit, while critical demand curtailment emerges as the most effective strategy for the power sector, and is also substantially helpful in alleviating high electricity prices for consumers. Smaller, and arguably more attainable, flexibility measures also prove consequential: shifting demand to coincide with solar output delivers noticeable system-wide advantages, even when the shift spans as little as two hours.

physics.soc-ph↗

arXiv2025

Energy and GHG saving potentials of sufficiency measures -- a synthesis for Germany

The sixth assessment report of the Intergovernmental Panel on Climate Change (IPCC) emphasises the potential of demand-side measures, such as sufficiency, for mitigating climate change. Although quantified potentials of various sufficiency measures exist, policy advisors and energy modellers criticise the lack of findability and comparability of the relevant data. Due to the high level of heterogeneity in units, reference points and calculation methods, the data cannot be used to summarise sufficiency potentials at a national level. Consequently, this paper aims to identify, structure, harmonise and synthesise existing data in order to determine the greatest saving potentials per sector and highlight data gaps. Based on a systematic literature review, we have created a curated open-source database containing over 300 quantified energy and greenhouse gas (GHG) saving potentials for Germany, which could be used as a blueprint for other such data collections. Most quantifications were available for the building sector, particularly for appliances. The highest total energy and GHG emission savings in Germany were identified in measures that reduce per capita living space, with saving potentials of -150 Terawatt-hours per year (TWh/a) and -118 Million Tons of Carbon Dioxide Equivalents per year (Mt CO2eq./a; this measure also includes lower heating temperatures). This synthesis can help modellers to better account for sufficiency potentials in scenarios, and help policymakers to understand the saving potentials of sufficiency. We encourage researchers to quantify more energy and GHG saving potentials in order to fill the identified gaps and to use the proposed synthesis structure.

physics.soc-ph↗

arXiv2025

Closing the Loop: Integrating Material Needs of Energy Technologies into Energy System Models

The transition to a climate-neutral energy system demands large-scale renewable generation expansion, which requires substantial amounts of bulk materials like steel, cement, and polymers. The production of these materials represents an additional energy demand for the system, creating an energy-material feedback loop. Current energy system models lack a complete representation of this feedback loop. Material requirements of energy system transformation have been studied in a retrospective approach, not allowing them as a consideration in system design. To address this gap, we integrate bulk material demand and production as endogenous factors into energy system optimization using PyPSA-Eur. Our approach links infrastructure expansion with industrial energy needs to achieve a minimum-cost equilibrium. Applying this model to Germany's transition to climate neutrality by 2045, we find that accounting for material needs increases annual bulk material demands by 3-9 %, shifts preferences from solar to wind and from local production of hydrogen to ship imports, and shows distinct industrial process route choices. These findings suggests that energy-material feedbacks should be considered in energy system design when moving to more domestic production of energy technologies.

physics.soc-ph↗

arXiv2025

Where do Germany's electricity imports come from?

In 2023, Germany's electricity trade balance shifted from net exports to net imports for the first time since 2002, resulting in an increasing discussion of these imports in the public debate. This study discusses different data driven approaches for the analysis of Germany's cross-border trade, with a focus on the methodological challenges to determine the origin of imported electricity within the framework of European electricity market coupling. While scheduled commercial flows from ENTSO-E are often used as indicators, generally these do not correspond to bilateral exchanges between different market actors. In particular, for day-ahead market coupling only net positions have an economically reasonable interpretation, and scheduled commercial exchanges are defined through ex-post algorithmic calculations. Any measure of the origin of electricity imports thus depends on some underlying interpretation and corresponding method, ranging from local flow patterns to correlations in net positions. To illustrate this dependence on methodological choices, we compare different approaches to determine the origin of electricity imports for hourly European power system data for 2024.

physics.soc-ph↗

arXiv2023

Right here, right now? The role of spatio-temporal minimum renewable shares for energy system transformation pathways

Energy system optimization models are important tools to provide insights regarding trade-offs and interrelations in cost-efficient transformation pathways towards a climate neutral energy system. Using an optimization model of the European electricity system, we study the influence of either an emission cap or temporally resolved minimum renewable generation shares as means to power system decarbonization. Such minimum shares serve as a stylized representation of novel, more granular procurement or certification schemes for renewable power generation. We observe that decarbonization through minimum shares results in a significant increase in system costs compared to the least cost solution obtained through a direct implementation of the corresponding emission reduction as a cap. Nevertheless, these shares provide direct incentives for expanding renewable generation and storage technologies, thus acting as an additional, potentially more robust decarbonization mechanism.

physics.soc-ph↗

arXiv2023

Load and generation time series for German federal states: Static vs. dynamic regionalization factors

Electricity generation and demand time series often are only available on a national scale. In this contribution, we derive regionalization factors to allocate publicly available national generation and demand time series for Germany to the federal-state level. We compare two different types of regionalization approaches: Static factors are based on the regional distribution of capacities or population and GPD, whereas dynamic factors take plant-specific generation time series, regionally resolved weather patterns or compositions of different load profiles into account. We observe that dynamic regionalization factors show significant temporal variability, emphasizing the limitations of static regionalization factors for a spatio-temporally more detailed representation of power system time series.

physics.soc-ph↗

arXiv2022

Open-data based carbon emission intensity signals for electricity generation in European countries -- top down vs. bottom up approach

Dynamic grid emission factors provide a temporally resolved signal about the carbon intensity of electricity generation in the power system. Since actual carbon dioxide emission measurements are usually lacking, such a signal must be derived from system-specific emission factors combined with power generation time series. We present a bottom-up method that allows deriving per country and per technology emission factors for European countries based on plant specific power generation time series and reported emissions from the European emissions trading mechanism. We have matched, 595 fossil generation units and their respective annual emissions. In 2018, these power plants supplied 717 TWh of electricity to the grid, representing approximately 50 % of power generation from fossil fuels. Based on this dataset, 42 individual technology and country-specific emission factors are derived. The resulting values for historical per country carbon intensity of electricity generation are compared with corresponding results from a top-down approach, which uses statistical data on emissions and power generation on national scales. All calculations are based on publicly available data, such that the analysis is transparent and the method can be replicated, adjusted and expanded in a flexible way.

physics.soc-ph↗

arXiv2020

Tracing carbon dioxide emissions in the European electricity markets

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.

physics.soc-ph↗

arXiv2019

Principal Cross-Border Flow Patterns in the European Electricity Markets

The interconnected European Electricity Markets see considerable cross-border trade between different countries. In conjunction with the structure and technical characteristics of the power grid and its operating rules, the corresponding commercial flows translate into actual physical flows on the interconnection lines. From the interplay of different physical, technical, and economic factors thus emerge complex spatiotemporal power flow patterns. Using Principal Component Analysis, in this contribution hourly time-series of cross-border physical flows between European countries in 2017 and 2018 are analyzed. The most important patterns in the time series of imports/exports and cross-border physical flows are identified. Their spatial and temporal structure, as well as their contribution to the overall variance is described. Additionally, we apply a tracing technique to the overall flow patterns, which allows identifying the physical power transfers between European countries through the common grid infrastructure.

physics.soc-ph↗

arXiv2018

Principal Flow Patterns across renewable electricity networks

Using Principal Component Analysis (PCA), the nodal injection and line flow patterns in a network model of a future highly renewable European electricity system are investigated. It is shown that the number of principal components needed to describe 95$\%$ of the nodal power injection variance first increases with the spatial resolution of the system representation. The number of relevant components then saturates at around 76 components for network sizes larger than 512 nodes, which can be related to the correlation length of wind patterns over Europe. Remarkably, the application of PCA to the transmission line power flow statistics shows that irrespective of the spatial scale of the system representation a very low number of only 8 principal flow patterns is sufficient to capture 95$\%$ of the corresponding spatio-temporal variance. This result can be theoretically explained by a particular alignment of some principal injection patterns with topological patterns inherent to the network structure of the European transmission system.

eess.SP↗

arXiv2018

Cost optimal scenarios of a future highly renewable European electricity system: Exploring the influence of weather data, cost parameters and policy constraints

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 generation, 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.

physics.soc-ph↗

arXiv2018

Flow-based analysis of storage usage in a low-carbon European electricity scenario

The application of the flow tracing method to power flows in and out of storage units allows to analyse the usage of this technology option in large-scale interconnected electricity systems. We apply this method to a data-driven model of the European electricity network, which uses a techno-economic optimisation to determine generation and storage capacities and dispatch, assuming a 95% reduction of CO2 emission compared to 1990 levels. A flow-based analysis of the power inflow into the different storage technologies confirms the intuition that longer-term hydrogen storage is mainly utilised for wind, whereas short-term battery storage mostly receives inflow from solar power generation. The usage of storage technologies in general shows a local-but-global behaviour: Whereas on average the power outflow from these capacities is predominantly consumed locally inside the same node, when exported it is also transmitted over long distances as a global flexibility option for the entire system.

physics.soc-ph↗

arXiv2018

Flow-based nodal cost allocation in a heterogeneous highly renewable European electricity network

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.

physics.soc-ph↗

arXiv2017

Scaling of transmission capacities in coarse-grained renewable electricity networks

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.

physics.soc-ph↗

arXiv2017

Flow tracing as a tool set for the analysis of networked large-scale renewable electricity systems

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.

physics.soc-ph↗

arXiv2015

Power flow tracing in a simplified highly renewable European electricity network

The increasing transmission capacity needs in a future energy system raise the question 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.

physics.soc-ph↗

arXiv2012

Experimental tests of pseudo-complex General Relativity

Based on previous publications exploring pseudo-complex General Relativity (pc-GR) we present a selection of observable consequences of pc-GR and possible ways to experimentally access them. Whenever possible we compare the results to Einstein's GR and differences are worked out in detail. We propose experimental tests to check the predictions of pc-GR for the orbital frequency of test particles, the gravitational redshift effect and the last stable orbit. We will show that the orbital frequency of test particles at a given radius in pc-GR is in general lower compared to standard GR. Also the effect of frame dragging is modified (weakened) in pc-GR. Concerning the gravitational redshift of a radiation emitting object we find that it is also lower in pc-GR than in standard GR. Eventually the classical concept of a last stable orbit has to be modified in pc-GR.

gr-qc↗

arXiv2012

Pseudo-Complex General Relativity: Schwarzschild, Reissner-Nordström and Kerr Solutions

The pseudo-complex General Relativity (pc-GR) is further considered. A new projection method is proposed. It is shown, that the pc-GR introduces automatically terms into the system which can be interpreted as dark energy. The modified pseudo-complex Schwarzschild solution is investigated. The dark energy part is treated as a liquid and possible solutions are discussed. As a consequence, the collapse of a large stellar mass into a singularity at $r=0$ is avoided and no event-horizon is formed. Thus, black holes don't exist. The resulting object can be viewed as a gray star. It contains no singularity which emphasizes, again, that it is not a black hole. The corrections implied by a charged large mass object (Reissner- Nordström) and a rotating gray star (Kerr) are presented. For the latter, a special solution is presented. Finally, we will consider the orbital speed of a mass in a circular orbit and suggest a possible experimental verification.

gr-qc↗