Main assumptions for energy pathways

© The Author(s) 2019. The aim of this chapter is to make the scenario calculations fully transparent and comprehensible to the scientific community. It provides the scenario narratives for the reference case (5.0 °C) as well as for the 2.0 °C and 1.5 °C on a global and regional basis. Cost projections for all fossil fuels and renewable energy technologies until 2050 are provided. Explanations are given for all relevant base year data for the modelling and the main input parameters such as GDP, population, renewable energy potentials and technology parameters

Über die Erreichbarkeit ambitionierter Klimaschutzziele : eine Analyse des Beitrags des Verkehrssektors und von variablen erneuerbaren Energien mit Hilfe von Energie-Wirtschafts-Klima-Modellen

Der anthropogene Klimawandel gefährdet das Wohlergehen der Menschheit. Aus diesem Grund haben Politiker wiederholt das Ziel formuliert, die Erhöhung der mittleren globalen Temperatur auf weniger als 2◦C über dem vorindustriellen Wert zu begrenzen. Dazu müssen die globalen Treibhausgasemissionen nahezu vollständig vermieden werden. Da das heutige globale System zur Energienutzung auf fossilen Rohstoffen beruht, erfordert die Reduktion von Treibhausgasemissionen eine fundamentale Umgestaltung unseres Energiesystems. Diese Arbeit erforscht die ökonomischen Anforderungen und Folgen von ambitionierten Klimaschutzzielen. Sie beginnt mit einer allgemeinen Analyse der charakteristischen Dekarbonisierungsmuster des globalen Energiesystems. Diese identifiziert zwei besonders relevante Aspekte von Klimaschutzszenarien: die Nutzung von variablen erneuerbaren Energien (VRE) für Emissionsminderungen im Stromsektor, sowie die Schwierigkeit der Dekarbonisierung des Verkehrssektors. Eine vertiefende Analyse der beiden Solartechnologien Photovoltaik (PV) und solarthermische Kraftwerke (CSP) mit dem IAM REMIND bestätigt die fundamentale Rolle dieser VRE für den Stromsektor. Aufgrund der in der letzten Dekade erreichten Kostensenkung ist PV mittlerweile in Regionen mit hohem mittäglichem Strombedarf und starker Sonneneinstrahlung konkurrenzfähig zu anderen Kraftwerksneubauten. Die Abbildung der Systemintegrationskosten in REMIND hat einen deutlichen Einfluss auf den Wettbewerb zwischen PV und CSP: CSP mit thermischem Speicher und Wasserstoff-Co-Feuerung kann gesicherte Leistung bereitstellen und hat deshalb niedrigere Integrationskosten als PV, wodurch CSP bei hohen Anteilen an VRE konkurrenzfähig wird. Eine modellübergreifende Studie zum Verkehrssektor bestätigt, dass dieser nur schwach auf CO2-Preise unter 100€/t CO2 Höhe reagiert: Bis 2050 hinken relative Emissionsreduktionen im Verkehrssektor 10–30 Jahre hinter denen in anderen Sektoren her, und Flüssigtreibstoffe bleiben Hauptenergieträger. Auf längere Sicht bis 2100 stellt der Verkehrssektor jedoch kein unüberwindbares Hindernis für ambitionierte Klimaschutzziele dar: Bei höheren CO2-Preisen zeigen die Modelle deutliche Reduktionen der Verkehrsemissionen, entweder mittels Wasserstoff-Brennstoffzellen bzw. batteriebetriebene Elektromobile oder mittels Biotreibstoffen der zweiten Generation (möglicherweise mit CCS). Die abschließende Studie beschäftigt sich mit dem Zusammenhang zwischen der Strenge eines Klimaschutzziels und den damit verbundenen technischen und ökonomischen Anforderungen und Folgen. Unsere Ergebnisse zeigen, dass die Umgestaltung des globalen Energiesystems, die zur Einhaltung des 2◦C-Zieles mit einer Zweidrittel-Wahrscheinlichkeit notwendig ist, zu moderaten ökonomischen Kosten erreichbar ist. Dieses Resultat ist abhängig von der zeitnahen Umsetzung umfassender globaler Emisssionsminderungsmaßnahmen sowie der Verfügbarkeit verschiedener Technologien, die die Marktreife noch nicht gänzlich erreicht haben. Verzögert man die Einführung starker Klimaschutzpolitik, so erhöhen sich die Kosten substantiell, was das Erreichen ambitionierter Klimaschutzziele gefährdet. In dieser Arbeit wurde eine umfassende Analyse ambitionierter Klimaschutzszenarien und ihrer ökonomischen Anforderungen und Folgen durchgeführt, wobei ein besonderer Fokus auf der Nutzung erneuerbarer Energien einerseits und Emissionsreduktionen im Verkehr andererseits lag. Auf Basis umfangreicher eigener Modellrechnungen und globaler Modellvergleiche liefert die Arbeit entscheidende Erkenntnisse und Strategien für das Erreichen ambitionierter Klimaschutzziele.Anthropogenic climate change is threatening the welfare of mankind. Accordingly, policy makers have repeatedly stated the goal of slowing climate change and limiting the increase of global mean temperature to less than 2 °C above pre-industrial times (the so-called “two degree target”). Stabilizing the temperature requires drastic reductions of greenhouse gas (GHG) emissions to nearly zero. As the global system of energy supply currently relies on fossil fuels, reducing GHG emissions can only be achieved through a full-scale transformation of the energy system. This thesis investigates the economic requirements and implications of different scenarios that achieve stringent climate mitigation targets. It starts with the analysis of characteristic decarbonization patterns and identifies two particularly relevant aspects of mitigation scenarios: deployment of variable renewable energies (VRE) and decarbonization of the transport sector. After investigating these fields in detail, we turned towards one of the most relevant questions for policy makers and analyzed the trade-off between the stringency of a climate target and its economic requirements and implications. All analyses are based on the improvement, application, comparison, and discussion of large-scale IAMs. The novel “mitigation share” metric allowed us to identify the relevance of specific technology groups for mitigation and to improve our understanding of the decarbonization patterns of different energy subsectors. It turned out that the power sector is decarbonized first and reaches lowest emissions, while the transport sector is slowest to decarbonize. For the power sector, non-biomass renewable energies contribute most to emission reductions, while the transport sector strongly relies on liquid fuels and therefore requires biomass in combination with carbon capture and sequestration (CCS) to reduce emissions. An in-depth investigation of the solar power technologies photovoltaics (PV) and concentrating solar power (CSP) in REMIND confirms the dominant role of these variable renewable energies for the decarbonization of the power sector. Recent cost reductions have brought PV to cost-competitiveness in regions with high midday electricity demand and high solar irradiance. The representation of system integration costs in REMIND is found to have significant impact on the competition between PV and CSP in the model: the low integration requirements of CSP equipped with thermal storage and hydrogen co-firing make CSP competitive at high shares of variable renewable energies, which leads to substantial deployment of both PV and CSP in low stabilization scenarios. A cross-model study of transport sector decarbonization confirms the earlier finding that the transport sector is not very reactive to intermediate carbon price levels: Until 2050, transport decarbonization lags 10-30 years behind the decarbonization of other sectors, and liquid fuels dominate the transport sector. In the long term, however, transportation does not seem to be an insurmountable barrier to stringent climate targets: As the price signals on CO2 increase further, transport emissions can be reduced substantially - if either hydrogen fuel cells or electromobility open a route to low-carbon energy carriers, or second generation biofuels (possibly in combination with CCS) allow the use of liquid-based transport modes with low emissions. The last study takes up the fundamental question of this thesis and analyses the trade-off between the stringency of a climate target and the resulting techno-economic requirements and costs. We find that transforming the global energy-economy system to keep a two-thirds likelihood of limiting global warming to below 2 °C is achievable at moderate economic implications. This result is contingent on the near-term implementation of stringent global climate policies and full availability of several technologies that are still in the demonstration phase. Delaying stringent policies and extending the current period of fragmented and weak action will substantially increase mitigation costs, such that stringent climate targets might be pushed out of reach. Should the current weak climate policies be extended until 2030, the transitional mitigation costs for keeping the 2 °C target would increase three-fold compared to a world in which global cooperative action is decided on in 2015 and where first deep emission reductions are achieved in 2020. In case of technology limitations, the urgency of reaching a global climate agreement is even higher. In this thesis, we performed a comprehensive analysis of stringent mitigation scenarios and their economic implications, with a special focus on VRE deployment and transport decarbonization. Based on extensive modeling work and global cross-model analyses, this thesis provides crucial insights and identifies strategies for achieving stringent mitigation targets

High-detail energy system modelling to support VRE technology representation in IAMs

In order to model variable renewable energy (VRE) integration into the power system, Integrated Assessment Models (IAM) need aggregated information on VRE availability and balancing requirements. We present exemplary applications of the high resolution energy system model REMix designed to support the representation of VRE technologies and integration costs in IAMs

Application of a high-detail energy system model to derive power sector characteristics at high wind and solar shares

Solar irradiation and wind speed vary with climatic, as well as seasonal and daily weather conditions. In order to represent these variable renewable energy (VRE) resources in specialized energy system models, high temporal and spatial resolution information on their availability is used. In contrast, Integrated Assessment Models (IAM), typically characterized by long term time scales and low temporal and spatial resolution, require aggregated information on VRE availability and balancing requirements at various levels of VRE penetration and mix. Parametric studies that provide such information typically regard solar energy synonymously with photovoltaic power generation. However, solar energy can also be harvested with Concentrating Solar Power (CSP) plants, which can be dispatchable if equipped with thermal storage. Accounting for this dispatchable use of the variable solar resource can change the balancing requirements at any solar energy penetration level. In this paper, we present an application of the high resolution energy system model REMix to a set of European supply scenarios with theoretical VRE shares ranging from 0 to 140%, three solar-to-wind ratios, with CSP included in the solar share. We evaluate balancing measures, curtailments and costs and compare the findings to previous results in which CSP is regarded a backup option among other dispatchable power plants. The results show that CSP potentials in Europe are widely exploited in most scenarios. System costs are found to be lowest for wind dominated systems or balanced mixes of wind and solar and for an overall VRE share between 40% for a low and 80% for a high scenario of the future CO2 emission certificate price. The comparison with previous results shows that storage capacity is the only system variable that is significantly affected by allocating CSP to the VRE resources category. It is reduced by 24% on average across all VRE shares and proportions and by around 80% at most

Using the sun to decarbonize the power sector: The economic potential of photovoltaics and concentrating solar power

Photovoltaics (PV) has recently undergone impressive growth and substantial cost decreases, while deployment for concentrating solar power (CSP) has been much slower. As the share of PV rises, the challenge of system integration will increase. This favors CSP, which can be combined with thermal storage and co-firing to reduce variability. It is thus an open question how important solar power will be for achieving climate mitigation targets, and which solar technology will be dominant in the long-term. We address these questions with the state-of-the-art integrated energy-economy-climate model REMIND 1.5, which embodies an advanced representation of the most important drivers of solar deployment. We derive up-to-date values for current and future costs of solar technologies. We calculate a consistent global resource potential dataset for both CSP and PV, aggregated to country-level. We also present a simplified representation of system integration costs of variable renewable energies, suitable for large-scale energy-economy-models. Finally, we calculate a large number of scenarios and perform a sensitivity study to analyze how robust our results are towards future cost reductions of PV and CSP

Decarbonizing global power supply under region-specific consideration of challenges and options of integrating variable renewables in the REMIND model

Abstract We present two advances in representing variable renewables (VRE) in global energy-economy-climate models: accounting for region-specific integration challenges for eight world regions and considering short-term storage. Both advances refine the approach of implementing residual load duration curves (RLDCs) to capture integration challenges. In this paper we derive RLDCs for eight world regions (based on region-specific time series for load, wind and solar) and implement them into the REMIND model. Therein we parameterize the impact of short-term storage using the highly-resolved model DIMES. All RLDCs and the underlying region-specific VRE time series are made available to the research community. We find that the more accurate accounting of integration challenges in REMIND does not reduce the prominent role of wind and solar in scenarios that cost-efficiently achieve the 2°C target. Until 2030, VRE shares increase to about 15-40% in most regions with limited deployment of short-term storage capacities (below 2% of peak load). The REMIND model's default assumption of large-scale transmission grid expansion allows smoothening variability such that VRE capacity credits are moderate and curtailment is low. In the long run, VRE become the backbone of electricity supply and provide more than 70% of global electricity demand from 2070 on. Integration options ease this transformation: storage on diurnal and seasonal scales (via flow batteries and hydrogen electrolysis) and a shift in the non-VRE capacity mix from baseload towards more peaking power plants. The refined RLDC approach allows for a more accurate consideration of system-level impacts of VRE, and hence more robust insights on the nature of power sector decarbonization and related economic impacts

Deutschland auf dem Weg aus der Gaskrise – Wie sich Klimaschutz und Energiesouveränität vereinen lassen

Von kurzfristigen Interventionen für die Energiesicherheit bis hin zu längerfristigen Weichenstellungen für den Kurs auf Klimaneutralität sind in den Sektoren Gebäude, Industrie und Energiewirtschaft massive Einsparungen beim Gasverbrauch unerlässlich. Ariadne-Fachleute buchstabieren erstmals im Modell- und Szenarienvergleich aus, welche Stellschrauben und Spielräume zur Verfügung stehen