• Energy Research

We present an energy transition pathway constrained by a total CO2 budget of 7 Gt allocated to the German energy system after 2020, the Budget Scenario (BS). We apply a normative backcasting approach for scenario building based on historical data and assumptions from existing scenario studies. The modeling approach combines a comprehensive energy system model (ESM) with REMix—a cost optimization model for power and heat that explicitly incorporates sector coupling. To achieve the necessary CO2 reduction, the scenario focuses on electrifying all end use sectors until 2030, adding 1.5–2 million electric vehicles to the road per year. In buildings, 400,000–500,000 heat pumps would be installed annually by 2030, and the share of district heating would double until 2050. In the scenario, coal needs to be phased out by 2030. Wind and Photovoltaic (PV) capacities would need to more than double to 290 GW by 2030 and reach 500 GW by 2050. The BS results indicate that a significant acceleration of the energy transition is necessary before 2030 and that this higher pace must be maintained thereafter until 2050.

The accelerated urbanization and industrialization in China is leading to major challenges due to rising energy demand and emissions. Cities in particular play an important role in the decision-making and implementation processes for the energy transition. However, they often have only limited local energy potential and are heavily dependent on supply regions. We therefore assess how a predominantly renewable power supply can be implemented based on the availability of local or imported renewable resources. We present a case study in which an advanced energy system model is parametrized and applied to address questions which are relevant to the transformation of the energy system in China. The model is capable of simultaneously optimizing investment decisions and hourly power balances of a scenario year, taking into account different storage technologies, regional power exchange and policy constraints such as carbon cap, carbon price and renewable portfolio standards. The study takes the Beijing-Tianjin-Hebei metropolitan region with Inner Mongolia as a supply region—considered as exemplary regions characterized by heterogeneous infrastructures, resources and consumption—as its model. Starting from a context-related normative energy scenario, we analyze a possible future electricity system under various assumptions using the Renewable Energy Mix (REMix) energy system model developed at the DLR (German Aerospace Center). Depending on the estimated potentials of renewable energies, technology costs and the projected electricity demand, the metropolitan region is mainly supplied with imported wind and solar power. A sensitivity analysis considers installed capacities, annual generation, CO2 emissions and costs. The results indicate that the assumption of storage costs is of great importance for the future total costs of an electricity system. Variations in other parameters led to different generation portfolios with similar system costs. Our results provide insights into future regional infrastructure needs, and underline the importance of regional coordination and governance for the energy transition in China.

The exploration and evaluation of strategies for decarbonizing the energy system is the subject of a series of national and international studies conducted by governmental, industrial and independent stakeholders. These studies play an important role in the energy policy debate on understanding and assessing different transformation paths of the energy system, technology options and their implications. They support strategic decisions on the type and scale of investments in the energy system under uncertain future conditions. However, in recent years the increasing complexity of these studies lead to a decreasing transparency even though their transparency and traceability is important for society, politics, research, and industry.In this article, three energy scenarios at different regional scales are reviewed according to their compliance with our pre-defined criteria of transparency. They are analysed in detail with regard to their objectives, methods, data used, results obtained and traceability. Our comparison shows that the results are often presented sufficiently in order to inform decision makers. However, the underlying model-based methods lack information on data exchange between the models, the transparent description of model couplings and a discussion on the rationality of method selection and the strengths and weaknesses of the applied approaches. Based on our findings, we present some general advice for energy scenario developers on how to ensure transparency and traceability in future energy scenario studies. Keywords: Energy scenario, Transparency, Reproducibility, Modelling approach, Impact

With the amendment to the German Climate Change Act in 2021, the Federal Government of Germany has set the target to become greenhouse gas neutral by 2045. Reaching this ambitious target requires multisectoral efforts, which in turn calls for interdisciplinary collaboration: the Net-Zero-2050 project of the Helmholtz Climate Initiative serves as an example of successful, interdisciplinary collaboration with the aim of producing valuable recommendations for action to achieve net-zero CO2 emissions in Germany. To this end, we applied an interdisciplinary approach to combining comprehensive research results from ten German national research centers in the context of carbon neutrality in Germany. In this paper, we present our approach and the method behind the interdisciplinary storylines development, which enabled us to create a common framework between different carbon dioxide removal and avoidance methods and the bigger carbon neutrality context. Thus, the research findings are aggregated into narratives: the two complementary storylines focus on technologies for net-zero CO2 emissions and on different framing conditions for implementing net-zero CO2 measures. Moreover, we outline the Net-Zero-2050 results emerging from the two storylines by presenting the resulting narratives in the context of carbon neutrality in Germany. Aiming at creating insights into how complementary and related expertise can be combined in teams across disciplines, we conclude with the project’s lessons learned. This paper sheds light on how to facilitate cooperation between different science disciplines with the purpose of preparing joint research results that can be communicated to a specific audience. Additionally, it provides further evidence that interdisciplinary and diverse research teams are an essential factor for defining solution spaces for complex, interdisciplinary problems.

Mit der Ratifizierung des Übereinkommens von Paris im Jahr 2016 hat sich China dem globalen Klimaziel verpflichtet, den globalen Temperaturanstieg deutlich unter 2 °C zu halten. Mit einem erwarteten beschleunigten Urbanisierungsprozess bis 2050 und einer hohen industriellen Aktivität steht China vor großen Herausforderungen, um eine umweltfreundliche Energieversorgung zu erreichen und insbesondere die CO2-Emissionen zu verringern. Insbesondere die Metropolregionen an der Ostküste spielen eine wichtige Rolle bei der Entscheidungsfindung und Umsetzung auf dem Weg zu einer dekarbonisierten Wirtschaft und Gesellschaft. Die nationalen und provinzialen Verwaltungen in China haben bereits begonnen, sich mit der Frage der Energiewende hin zu einem kohlenstoffarmen System zu befassen, aber auf regionaler Ebene liegen noch keine langfristigen integrierten Übergangspläne vor. In dieser Arbeit konzentriere ich mich daher auf zwei Metropolregionen Ostchinas (Peking-Tianjin-Hebei-Region im Norden und Yangtse-Delta-Region im Süden) mit hohem Energieverbrauch und damit verbundenen CO2-Emissionen. Die Analyse beginnt mit den wichtigsten Herausforderungen, denen sich die Regionen im Hinblick auf die Energiewende und die bestehenden energiepolitischen Pläne auf verschiedenen Verwaltungsebenen gegenübersehen. Die Überprüfung zeigt, dass die derzeitige Politik in Bezug auf die Kopplung der Sektoren und die regionale Integration eher kurzfristig und schwach ist. Da sich in China die wirtschaftlichen Aktivitäten und die Bevölkerung auf die östlichen Küstenregionen konzentrieren, während sich die erneuerbaren Energiequellen auf die westlichen Binnenregionen konzentrieren, müssen bei der Modellierung langfristiger integrierter Energiesysteme spezifische regionale Herausforderungen und Bedingungen berücksichtigt werden. In meiner Arbeit werden daher drei Szenarien konstruiert, nämlich das aktuelle politische Szenario (CPS), das Erdgas- und Nuklearszenario (NGNS) und das erneuerbare und importierte Szenario (RIS), die auf einem normativen Storyline- und Modellierungsansatz basieren. Die Szenarioanalyse zeigt, dass die regionalen CO2-Emissionen in allen Sektoren erheblich reduziert werden könnten, indem die Wirtschaftsstruktur angepasst, Effizienzmaßnahmen umgesetzt, Kohle und Öl ersetzt und die sektorübergreifende Elektrifizierung durch verbesserte Stromimportkapazitäten unterstützt werden. Aufgrund der massiven Elektrifizierung bleiben die CO2-Emissionen in beiden Regionen hauptsächlich bei der Gasverbrennung im Stromsektor. Der Szenariovergleich liefert Einblicke in die Anforderungen der Energiewende hinsichtlich der Implementierung neuer Technologien und deren Auswirkungen. Somit kann es als Grundlage für die Ableitung politischer Strategien aus einer langfristigen Perspektive dienen, um den Übergangsprozess in Metropolregionen sowohl von der Angebots- als auch von der Nachfrageseite weiter zu gestalten. Um die Importoptionen aus erneuerbarem Strom für die Metropolregionen zu analysieren, ich konzentriere mich eine Fallstudie auf die Region Peking-Tianjin-Hebei mit der Inneren Mongolei als Versorgungsregion. Hauptforschungsfragen sind, wie eine überwiegend erneuerbare Energieversorgung implementiert werden kann und welche Anteile lokal verfügbarer oder importierter erneuerbarer Ressourcen genutzt werden können. Basierend auf dem erneuerbaren und importierten Szenario (RIS) werden die zukünftigen Stromversorgungssysteme anhand des am DLR entwickelten REMix-Energiesystemmodells weiter analysiert, das einen kostenminimierenden Algorithmus verwendet. Zeitlich und räumlich aufgelöste Lastprofile sowie variable Wind- und Sonnenenergieerzeugung sind die wichtigsten Eingangsdaten. Eine Sensitivitätsanalyse für Schlüsselparameter liefert wichtige Informationen zur Robustheit und den Wechselwirkungen bei der Modellierung. Die Ergebnisse liefern Einblicke in die Infrastrukturanforderungen wie Speicher und Netzausbau. Die obige modellbasierte Szenarioanalyse hängt von einer Reihe wichtiger Annahmen ab und führt hauptsächlich aus Systemsicht zu Schlussfolgerungen. Es zeigt, dass die östlichen Metropolregionen größtenteils zu angemessenen Kosten mit importiertem Strom aus Onshore-Wind- und Solarkraftwerken im Westen versorgt werden könnten. Regionale Koordination und Governance, die Errichtung von Energie- und Kohlenstoffmärkten sind daher entscheidende Faktoren für erfolgreiche Energiewendeprozesse auf verschiedenen Verwaltungsebenen. Die regional integrierte Modellierung des Energiesystems kann die Entscheidungsfindung bei der Implementierung neuer Technologien und Infrastrukturoptionen für Metropolregionen unterstützen, um die langfristigen Klimaziele zu erreichen. Ratifying the Paris Treaty in 2016, China committed itself to the global climate target to keep the global temperature increase well below 2 °C. With an expected accelerated urbanization process until 2050 and high industrial activity, China faces big challenges in achieving an environmentally friendly energy supply and, in particular, mitigating CO2 emissions. Especially the eastern coastal metropolitan regions are playing an important role in decision making and implementation processes on the way to a decarbonized economy and society. The national and provincial administrations in China have already started to address the issue of energy transition towards a low-carbon system, but long-term integrated transition plans are not yet available on the regional level. In this thesis I therefore focus on two metropolitan regions of eastern China (Beijing-Tianjin-Hebei region in the north and Yangtze River Delta region in the south) with high energy consumption and related CO2 emissions. The analysis starts with the main challenges the regions are facing with regard to energy transition and the existing energy policy plans on different administrative levels. The review shows that the current policies are rather short-term driven and weak regarding sector coupling and regional integration. As in China economic activities and population are concentrated in the eastern coastal regions, while renewable energy resources are concentrated in the western inland regions, specific regional challenges and conditions must be taken into account when modelling long-term integrated energy systems. In my thesis, three scenarios are therefore constructed, namely the Current Policy Scenario (CPS), the Natural Gas & Nuclear Scenario (NGNS) and the Renewable & Import Scenario (RIS), which are based on a normative storyline-and-modelling approach. The scenario analysis shows that regional CO2 emissions could be significantly reduced in all sectors by adjusting the economic structure, implementing efficiency measures, replacing coal and oil, and multi-sector electrification supported by enhanced electricity import capacities. Due to the massive electrification, CO2 emissions in both regions will remain mainly from gas combustion in the power sector. The scenario comparison provides insights into requirements of the energy transition regarding the implementation of new technologies and their effects. Thus, it can serve as a basis for deriving political strategies from long-term perspective to further shape the transition process in metropolitan regions from both the supply and the demand side. In order to analyze import options from renewable electricity for the metropolitan regions, a case study focusses on the Beijing-Tianjin-Hebei region with Inner Mongolia as the supply region. Main research questions are how a predominantly renewable energy power supply can be implemented and which shares of locally available or imported renewable resources can be used. Based on the Renewable & Import Scenario (RIS), the future power systems are further analyzed applying the REMix energy system model developed at DLR, which uses a cost-minimizing algorithm. Temporally and spatially resolved load profiles and variable wind and solar power generation are the most important input data. A sensitivity analysis for key parameters provides important information on the robustness and interactions in modelling. The results provide insights into the infrastructural needs such as storage and grid expansion. The above model-based scenario analysis depends on a number of key assumptions and leads to conclusions mainly from a system perspective. It demonstrates that the eastern metropolitan regions could largely be supplied with imported electricity from onshore wind and solar power plants in the west at reasonable costs. Therefore, regional coordination and governance, the establishment of energy and carbon markets are crucial factors for successful energy transition processes at different administrative levels. Regionally integrated modelling of the energy system can support decision making in the implementation of new technologies and infrastructure options for metropolitan regions to achieve the long-term climate targets.

The scenario analysis focuses on two metropolitan regions of eastern China which are characterized by high energy consumption and related CO2 emissions. Current policies are rather short-term driven and weak regarding sectoral coupling and regional integration. As in China economic activities and population on the one hand and renewable energy resources on the other have a very imbalanced distribution, long-term integrated energy system modelling needs to consider specific regional challenges of efficiency improvement, coal reduction, transport decarbonization and multi-sector electrification. Three scenarios are constructed, namely a Current Policy Scenario (CPS), Natural Gas & Nuclear Scenario (NGNS) and Renewable & Import Scenario (RIS) based on a normative storyline-and-modelling approach. The simulation results show that regional CO2 emissions could be significantly reduced in all sectors with the adjustment of economic structure, adopted efficiency measures, fuels to replace coal and oil products and multi-sector electrification supported by enhanced power import capacity. The scenario analysis provides insights for a strategic implementation of long-term integrated energy transition options towards decarbonization for metropolitan regions both from supply and demand sides. Keywords: Energy system transition, Renewable energy, Eastern China, Scenario analysis, CO2 targets, Regional integration