TY - JOUR A1 - Ruhnau, Oliver A1 - Bannik, Sergej A1 - Otten, Sydney A1 - Praktiknjo, Aaron A1 - Robinius, Martin T1 - Direct or indirect electrification? A review of heat generation and road transport decarbonisation scenarios for Germany 2050 JF - Energy N2 - Energy scenarios provide guidance to energy policy, not least by presenting decarbonisation pathways for climate change mitigation. We review such scenarios for the example of Germany 2050, with a focus on the decarbonisation of heat generation and road transport. In this context, we characterize the role of renewable electricity and contrast two rivalling narratives: direct and indirect electrification. On the one hand, electricity directly provides heat and transport, using electric heat pumps, electric heaters, and battery electric vehicles. On the other hand, electricity, heat, and transport are indirectly linked, using gas heat pumps, gas heaters, fuel cell electric vehicles, and internal combustion engine vehicles, in combination with power-to-gas and power-to-liquid processes. To reach climate policy targets, our findings imply that energy stakeholders must (1) plan for the significant additional demand for renewable electricity for heat and road transport, (2) pave the way for system-friendly direct heat electrification, (3) be aware of technological uncertainties in the transport sector, (4) clarify the vision for decarbonisation, particularly for road transport, and (5) use holistic and more comparable scenario frameworks. Y1 - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b1570-opus4-30602 U6 - https://doi.org/10.1016/j.energy.2018.10.114 SN - 0360-5442 VL - 166 IS - 1 SP - 989 EP - 999 ER - TY - JOUR A1 - Ruhnau, Oliver A1 - Hirth, Lion A1 - Praktiknjo, Aaron T1 - Time series of heat demand and heat pump efficiency for energy system modeling JF - Nature Scientific Data N2 - With electric heat pumps substituting for fossil-fueled alternatives, the temporal variability of their power consumption becomes increasingly important to the electricity system. To easily include this variability in energy system analyses, this paper introduces the “When2Heat” dataset comprising synthetic national time series of both the heat demand and the coefficient of performance (COP) of heat pumps. It covers 16 European countries, includes the years 2008 to 2018, and features an hourly resolution. Demand profiles for space and water heating are computed by combining gas standard load profiles with spatial temperature and wind speed reanalysis data as well as population geodata. COP time series for different heat sources – air, ground, and groundwater – and different heat sinks – floor heating, radiators, and water heating – are calculated based on COP and heating curves using reanalysis temperature data. The dataset, as well as the scripts and input parameters, are publicly available under an open source license on the Open Power System Data platform. Y1 - 2019 U6 - https://doi.org/10.1038/s41597-019-0199-y N1 - Open Access publication VL - 6 IS - 189 ER - TY - JOUR A1 - Ruhnau, Oliver A1 - Hirth, Lion A1 - Praktiknjo, Aaron T1 - Heating with Wind: Economics of heat pumps and variable renewables JF - Energy Economics N2 - With the growth of wind and solar energy in electricity supply, the electrification of space and water heating is becoming a promising decarbonization option. In turn, such electrification may help the power system integration of variable renewables, for two reasons: thermal storage could provide low-cost flexibility, and heat demand is seasonally correlated with wind power. However, temporal fluctuations in heat demand may also imply new challenges for the power system. This study assesses the economic characteristics of electric heat pumps and wind energy and studies their interaction on wholesale electricity markets. Using a numerical electricity market model, we estimate the economic value of wind energy and the economic cost of powering heat pumps. We find that, just as expanding wind energy depresses its €/MWhel value, adopting heat pumps increases their €/MWhel cost. This rise can be mitigated by synergistic effects with wind power, “system-friendly” heat pump technology, and thermal storage. Furthermore, heat pumps raise the wind market value, but this effect vanishes if accounting for the additional wind energy needed to serve the heat pump load. Thermal storage facilitates the system integration of wind power but competes with other flexibility options. For an efficient adoption of heat pumps and thermal storage, we argue that retail tariffs for heat pump customers should reflect their underlying economic cost. Y1 - 2020 U6 - https://doi.org/10.1016/j.eneco.2020.104967 VL - 92 ER - TY - JOUR A1 - Ruhnau, Oliver A1 - Bannik, Sergej A1 - Otten, Sydney A1 - Praktiknjo, Aaron A1 - Robinius, Martin T1 - Direct or indirect electrification? A review of heat generation and road transport decarbonisation scenarios for Germany 2050 JF - Energy N2 - Energy scenarios provide guidance to energy policy, not least by presenting decarbonisation pathways for climate change mitigation. We review such scenarios for the example of Germany 2050, with a focus on the decarbonisation of heat generation and road transport. In this context, we characterize the role of renewable electricity and contrast two rivalling narratives: direct and indirect electrification. On the one hand, electricity directly provides heat and transport, using electric heat pumps, electric heaters, and battery electric vehicles. On the other hand, electricity, heat, and transport are indirectly linked, using gas heat pumps, gas heaters, fuel cell electric vehicles, and internal combustion engine vehicles, in combination with power-to-gas and power-to-liquid processes. To reach climate policy targets, our findings imply that energy stakeholders must (1) plan for the significant additional demand for renewable electricity for heat and road transport, (2) pave the way for system-friendly direct heat electrification, (3) be aware of technological uncertainties in the transport sector, (4) clarify the vision for decarbonisation, particularly for road transport, and (5) use holistic and more comparable scenario frameworks. Y1 - 2018 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b1570-opus4-31063 U6 - https://doi.org/10.1016/j.energy.2018.10.114 SN - 0360-5442 N1 - This is a post-peer-review, pre-copyedit version of an article published in Energy. The final authenticated version is available online at: https://doi.org/10.1016/j.energy.2018.10.114 VL - 166 IS - 1 SP - 989 EP - 999 ER - TY - CHAP A1 - Madlener, Reinhard A1 - Ruhnau, Oliver ED - Sioshansi, Fereidoon T1 - Variable renewables and demand flexibility: Day-ahead versus intraday valuation T2 - Variable Generation, Flexible Demand N2 - This chapter discusses trading in the day-ahead and intraday electricity markets, first in general and then from the perspectives of renewable power generators and demand response, respectively. This includes an overview of the relevant literature, a theoretical framework, and illustrative quantitative examples. The uncertainty of renewable electricity supply drives price volatility, especially in the intraday market, and leads to balancing cost for renewables, which can be optimized through forecasting and trading. The increased intraday price volatility can be exploited and moderated by demand response, which thereby helps to balance the uncertainty of renewables. KW - Centre for Sustainability Y1 - 2020 SN - 9780128238103 U6 - https://doi.org/10.1016/B978-0-12-823810-3.00005-4 SP - 309 EP - 327 PB - Academic Press ER - TY - RPRT A1 - Ruhnau, Oliver T1 - Market-based renewables: How flexible hydrogen electrolyzers stabilize wind and solar market values N2 - Wind and solar energy are often expected to fall victim to their own success: the higher their share in electricity production, the more their revenue on electricity markets (their “market value”) declines. While in conventional power systems, the market value may converge to zero, this study demonstrates that “green” hydrogen production, through adding electricity demand in low-price hours, can effectively and permanently halt the decline. With an analytical derivation, a Monte Carlo simulation, and a numerical electricity market model, I find that – due to flexible hydrogen production – market values in 2050 likely converge above €19 ± 9 per MWh for solar energy and above €27 ± 8 per MWh for wind energy. This is in the range of the projected levelized costs of renewables and has profound implications. Market-based renewables may hence be within reach. KW - Renewable energy KW - Hydrogen electrolysis KW - Electricity market KW - Electricity economics KW - Integrated energy system Y1 - 2020 UR - https://www.econstor.eu/handle/10419/227075 ER - TY - JOUR A1 - Pöstges, Arne A1 - Bucksteeg, Michael A1 - Ruhnau, Oliver A1 - Böttger, Diana A1 - Haller, Markus A1 - Künle, Eglantine A1 - Ritter, David A1 - Schmitz, Richard A1 - Wiedmann, Michael T1 - Phasing out coal - An impact analysis comparing five large-scale electricity market models N2 - Climate target achievement has a crucial influence on the modelling and the decision processes in the energy sector. It induced the development of several policy instruments to mitigate greenhouse gas emissions, including administrative and market-based mechanisms for phasing out coal-fired generation technologies. In order to analyse such instruments, electricity market and energy system models are widely used. However, results and corresponding recommendations largely depend on the formulation of the respective model. This motivates a systematic comparison of five large-scale electricity market models which are applied to European scenarios considering the period until 2030. An evolved diff-in-diff approach is proposed to analyse the effects of two coal phase-out strategies. This contribution expands on that of earlier studies and provides some more general takeaways for both modellers and decision-makers. For instance, the evolved diff-in-diff analysis shows the influence of the reference scenario when evaluating a policy instrument. Furthermore, the importance of technical aspects such as constraints for combined heat and power plants are discussed and implications regarding three dimensions (economic, environmental, and security of supply) are presented. KW - model comparison, coal phase-out, electricity market model, energy policy KW - Centre for Sustainability Y1 - 2022 U6 - https://doi.org/https://www.econstor.eu/handle/10419/234102 PB - Applied Energy Vol. 319 ER - TY - JOUR A1 - Ruhnau, Oliver A1 - Bucksteeg, Michael A1 - Ritter, David A1 - Schmitz, Richard A1 - Böttger, Diana A1 - Koch, Matthias A1 - Pöstges, Arne A1 - Wiedmann, Michael A1 - Hirth, Lion T1 - Why electricity market models yield different results: Carbon pricing in a model-comparison experiment N2 - The European electricity industry, the dominant sector of the world’s largest cap-and-trade scheme, is one of the most-studied examples of carbon pricing. In particular, numerical models are often used to study the uncertain future development of carbon prices and emissions. While parameter uncertainty is often addressed through sensitivity analyses, the potential uncertainty of the models themselves remains unclear from existing single-model studies. Here, we investigate such model-related uncertainty by running a structured model comparison experiment, in which we exposed five numerical power sector models to aligned input parameters—finding stark model differences. At a carbon price of 27 EUR/t in 2030, the models estimate that European power sector emissions will decrease by 36–57% when compared to 2016. Most of this variation can be explained by the extent to which models consider the market-driven decommissioning of coal- and lignite-fired power plants. Higher carbon prices of 57 and 87 EUR/t yield a stronger decrease in carbon emissions, by 45–75% and 52–80%, respectively. The lower end of these ranges can be attributed to the short-term fuel switch captured by dispatch-only models. The higher reductions correspond to models that additionally consider market-based investment in renewables. By further studying cross-model variation in the remaining emissions at high carbon prices, we identify the representation of combined heat and power as another crucial driver of differences across model results. KW - Carbon pricing, EU Emission Trading System (EU ETS), electricity decarbonization, power sector, renewable energy, fuel switch, combined heat and power, electricity market modeling, model comparison, model-related uncertainty KW - Centre for Sustainability Y1 - 2022 U6 - https://doi.org/10.1016/j.rser.2021.111701 N1 - Preprint version available here: https://www.econstor.eu/handle/10419/234468 ER - TY - JOUR A1 - Cloete, Schalk A1 - Ruhnau, Oliver A1 - Cloete, Jan Hendrik A1 - Hirth, Lion T1 - Blue hydrogen and industrial base products: The future of fossil fuel exporters in a net-zero world N2 - Is there a place for today’s fossil fuel exporters in a low-carbon future? This study explores trade channels between energy exporters and importers using a novel electricity-hydrogen-steel energy systems model calibrated to Norway, a major natural gas producer, and Germany, a major energy consumer. Under tight emission constraints, Norway can supply Germany with electricity, (blue) hydrogen, or natural gas with re-import of captured CO2. Alternatively, it can use hydrogen to produce steel through direct reduction and supply it to the world market, an export route not available to other energy carriers due to high transport costs. Although results show that natural gas imports with CO2 capture in Germany is the least-cost solution, avoiding local CO2 handling via imports of blue hydrogen (direct or embodied in steel) involves only moderately higher costs. A robust hydrogen demand would allow Norway to profitably export all its natural gas production as blue hydrogen. However, diversification into local steel production, as one example of easy-to-export industrial base products, offers an effective hedge against the possibility of lower European blue hydrogen demand. Thus, it is recommended that hydrocarbon exporters like Norway consider a strategic energy export transition to a diversified mix of blue hydrogen and climate-neutral industrial base products. KW - Hydrogen economy, Energy-intensive industry, Decarbonization, CO2 capture and storage, Variable renewable energy KW - Centre for Sustainability Y1 - 2022 U6 - https://doi.org/10.1016/j.jclepro.2022.132347 PB - Journal of Cleaner Production Vo. 363 ER - TY - JOUR A1 - Eicke, Anselm A1 - Ruhnau, Oliver A1 - Hirth, Lion T1 - Electricity balancing as a market equilibrium: An instrument-based estimation of supply and demand for imbalance energy N2 - Frequency stability requires equalizing supply and demand for electricity at short time scales. Such electricity balancing is often understood as a sequential process in which random shocks, such as weather events, cause imbalances that system operators close by activating balancing reserves. By contrast, we study electricity balancing as a market where the equilibrium price (imbalance price) and quantity (system imbalance) are determined by supply and demand. System operators supply imbalance energy by activating reserves; market parties that, deliberately or not, deviate from schedules create a demand for imbalance energy. The incentives for deliberate strategic deviations emerge from wholesale market prices and the imbalance price. We empirically estimate the demand curve of imbalance energy, which describes how sensitive market parties are to imbalance prices. To overcome the classical endogeneity problem of price and quantity, we deploy instruments derived from a novel theoretical framework. Using data from Germany, we find a decline in the demand for imbalance energy by 2.2 MW for each increase in the imbalance price by EUR 1 per MWh. This significant price response is remarkable because the German regulator prohibits strategic deviations. We also estimate cross-market equilibriums between intraday and imbalance markets, finding that a shock to the imbalance price triggers a subsequent adjustment of the intraday price. KW - Electricity balancing, Intraday electricity market, Imbalance energy KW - Centre for Sustainability Y1 - 2021 U6 - https://doi.org/10.1016/j.eneco.2021.105455 ER -