@techreport{HirthKhannaRuhnau, type = {Working Paper}, author = {Hirth, Lion and Khanna, Tarun and Ruhnau, Oliver}, title = {The (very) short-term price elasticity of German electricity demand}, abstract = {Electricity is a peculiar economic good, the most important reason being that it needs to be supplied at the very moment of consumption. As a result, wholesale electricity prices fluctuate widely at hourly or sub-hourly time scales, regularly reaching multiples of their average, and even turn negative. This paper examines whether the demand for electricity responds to such price variations in the very short term. To solve the classical identification problem when estimating a demand curve, we use weather-driven wind energy generation as an instrument. Our robustness checks confirm that wind energy is indeed a strong and valid instrument. Using data from Germany, we estimate that a 1 €/MWh increase in the wholesale electricity price causes the aggregate electricity demand to decline by 67-80 MW or 0.12-0.14\%, contradicting the conventional wisdom that electricity demand is highly price-inelastic. These estimates are statistically significant and robust across model specifications, estimators, and sensitivity analyses. At average price and demand, our estimates correspond to a price elasticity of demand of about -0.05. Comparing situations with high and low wind energy (5-95th percentile), we estimate that prices vary by 26 €/MWh, and the corresponding demand response to wholesale electricity prices is about 2 GW, or 2.6\% of peak load. Our analysis suggests that the demand response in Germany can be attributed primarily to industrial consumers.}, language = {en} } @article{RuhnauEickeSgarlatoetal., author = {Ruhnau, Oliver and Eicke, Anselm and Sgarlato, Raffaele and Tr{\"o}ndle, Tim and Hirth, Lion}, title = {Cost-Potential Curves of Onshore Wind Energy: the Role of Disamenity Costs}, series = {Environmental and Resource Economics}, journal = {Environmental and Resource Economics}, doi = {10.1007/s10640-022-00746-2}, abstract = {Numerical optimization models are used to develop scenarios of the future energy system. Usually, they optimize the energy mix subject to engineering costs such as equipment and fuel. For onshore wind energy, some of these models use cost-potential curves that indicate how much electricity can be generated at what cost. These curves are upward sloping mainly because windy sites are occupied first and further expanding wind energy means deploying less favorable resources. Meanwhile, real-world wind energy expansion is curbed by local resistance, regulatory constraints, and legal challenges. This presumably reflects the perceived adverse effect that onshore wind energy has on the local human population, as well as other negative external effects. These disamenity costs are at the core of this paper. We provide a comprehensive and consistent set of cost-potential curves of wind energy for all European countries that include disamenity costs, and which can be used in energy system modeling. We combine existing valuation of disamenity costs from the literature that describe the costs as a function of the distance between turbine and households with gridded population data, granular geospatial data of wind speeds, and additional land-use constraints to calculate such curves. We find that disamenity costs are not a game changer: for most countries and assumptions, the marginal levelized cost of onshore wind energy increase by 0.2-12.5 €/MWh.}, language = {en} } @techreport{StieweRuhnauHirth, type = {Working Paper}, author = {Stiewe, Clemens and Ruhnau, Oliver and Hirth, Lion}, title = {European industry responds to high energy prices: The case of German ammonia production.}, pages = {6}, abstract = {Since September 2021, European natural gas prices are at record-high levels. On average, they have been six to seven times higher than pre-pandemic price levels. While the post-pandemic recovery of global natural gas demand has driven up prices around the world, the most important drivers for European gas prices were Russia's less-than-usual supply since mid-2021 and its invasion of Ukraine in February 2022. Western efforts to abandon Russian gas imports altogether mean that high natural gas prices are likely to stay for longer. While high gas prices may be the new normal, there is uncertainty about the economic reaction to this shock. How do energy-intensive industries react? Do global value chains collapse if intermediate goods produced in Europe become uneconomic because of high energy prices? Our preliminary analysis shows that industry response to has in fact been visible from the very onset of the energy crisis. A closer look at German fertilizer production, which heavily relies on natural gas as fuel and feedstock to produce ammonia as an intermediate product, reveals that increased ammonia imports have allowed domestic fertilizer production to remain remarkably stable.}, language = {en} } @article{WinzerRamirezMolinaHirthetal., author = {Winzer, Christian and Ram{\´i}rez-Molina, H{\´e}ctor and Hirth, Lion and Schlecht, Ingmar}, title = {Profile contracts for electricity retail customers}, series = {Energy Policy}, volume = {195}, journal = {Energy Policy}, publisher = {Elsevier BV}, issn = {0301-4215}, doi = {10.1016/j.enpol.2024.114358}, abstract = {Decarbonization involves a large-scale expansion of low-carbon generators such as wind and solar and the electrification of heating and transport. Both space heating and battery-electric cars have significant embedded flexibility potential. Granular price signals that convey abundance or scarcity of electricity are a precondition for customers or aggregators acting on their behalf to exploit this flexibility. However, unmitigated real-time prices expose customers to electricity price risks. To tackle the dual need of providing flexibility incentives while protecting customers from cost shocks, real-time tariffs with a hedging component can be a solution. In such contracts customers pre-agree an amount of energy and a consumption profile, while hourly deviations are charged at spot prices. In this paper we analyze design options by using a dataset of anonymized smart meter data and show that profile tariffs can bring electricity bill volatility to similarly low levels as fixed tariffs while providing full flexibility incentives from spot prices.}, language = {en} } @techreport{XuSanchezCanalesFusarBassinietal., type = {Working Paper}, author = {Xu, Alice Lixuan and S{\´a}nchez Canales, Jorge and Fusar Bassini, Chiara and Kaack, Lynn H. and Hirth, Lion}, title = {Market power abuse in wholesale electricity markets}, publisher = {arXiv}, doi = {10.48550/arXiv.2506.03808}, pages = {39}, abstract = {In wholesale electricity markets, prices fluctuate widely from hour to hour and electricity generators price-hedge their output using longer-term contracts, such as monthly base futures. Consequently, the incentives they face to drive up the power prices by reducing supply has a high hourly specificity, and because of hedging, they regularly also face an incentive to depress prices by inflating supply. In this study, we explain the dynamics between hedging and market power abuse in wholesale electricity markets and use this framework to identify market power abuse in real markets. We estimate the hourly economic incentives to deviate from competitive behavior and examine the empirical association between such incentives and observed generation patterns. Exploiting hourly variation also controls for potential estimation bias that do not correlate with economic incentives at the hourly level, such as unobserved cost factors. Using data of individual generation units in Germany in a six-year period 2019-2024, we find that in hours where it is more profitable to inflate prices, companies indeed tend to withhold capacity. We find that the probability of a generation unit being withheld increases by about 1 \% per euro increase in the net profit from withholding one megawatt of capacity. The opposite is also true for hours in which companies benefit financially from lower prices, where we find units being more likely to be pushed into the market by 0.3 \% per euro increase in the net profit from capacity push-in. We interpret the result as empirical evidence of systematic market power abuse.}, language = {en} } @techreport{FusarBassiniXuSanchezCanalesetal., type = {Working Paper}, author = {Fusar Bassini, Chiara and Xu, Alice Lixuan and S{\´a}nchez Canales, Jorge and Hirth, Lion and Kaack, Lynn}, title = {Revealing the empirical flexibility of gas units through deep clustering}, publisher = {arXiv}, doi = {10.48550/arXiv.2504.16943}, pages = {19}, abstract = {The flexibility of a power generation unit determines how quickly and often it can ramp up or down. In energy models, it depends on assumptions on the technical characteristics of the unit, such as its installed capacity or turbine technology. In this paper, we learn the empirical flexibility of gas units from their electricity generation, revealing how real-world limitations can lead to substantial differences between units with similar technical characteristics. Using a novel deep clustering approach, we transform 5 years (2019-2023) of unit-level hourly generation data for 49 German units from 100 MWp of installed capacity into low-dimensional embeddings. Our unsupervised approach identifies two clusters of peaker units (high flexibility) and two clusters of non-peaker units (low flexibility). The estimated ramp rates of non-peakers, which constitute half of the sample, display a low empirical flexibility, comparable to coal units. Non-peakers, predominantly owned by industry and municipal utilities, show limited response to low residual load and negative prices, generating on average 1.3 GWh during those hours. As the transition to renewables increases market variability, regulatory changes will be needed to unlock this flexibility potential.}, language = {en} } @techreport{FusarBassiniXuSanchezCanalesetal., type = {Working Paper}, author = {Fusar Bassini, Chiara and Xu, Alice Lixuan and S{\´a}nchez Canales, Jorge and Hirth, Lion and Kaack, Lynn H.}, title = {Flexibility of German gas-fired generation: evidence from clustering empirical operation}, publisher = {arXiv}, doi = {10.48550/arXiv.2504.16943}, pages = {29}, abstract = {A key input to energy models are assumptions about the flexibility of power generation units, i.e., how quickly and often they can start up. These assumptions are usually calibrated on the technical characteristics of the units, such as installed capacity or technology type. However, even if power generation units technically can dispatch flexibly, service obligations and market incentives may constrain their operation. Here, we cluster over 60\% of German national gas generation (generation units of 100 MWp or above) based on their empirical flexibility. We process the hourly dispatch of sample units between 2019 and 2023 using a novel deep learning approach, that transforms time series into easy-to-cluster representations. We identify two clusters of peaker units and two clusters of non-peaker units, whose different empirical flexibility is quantified by cluster-level ramp rates. Non-peaker units, around half of the sample, are empirically less flexible than peakers, and make up for more than 83\% of sample must-run generation. Regulatory changes addressing the low market responsiveness of non-peakers are needed to unlock their flexibility.}, language = {en} } @techreport{TiedemannSgarlatoHirth, type = {Working Paper}, author = {Tiedemann, Silvana and Sgarlato, Raffaele and Hirth, Lion}, title = {Price elasticity of electricity demand: Using instrumental variable regressions to address endogeneity and autocorrelation of high-frequency time series}, publisher = {arXiv}, doi = {10.48550/arXiv.2306.12863}, pages = {25}, abstract = {This paper examines empirical methods for estimating the response of aggregated electricity demand to high-frequency price signals, the short-term elasticity of electricity demand. We investigate how the endogeneity of prices and the autocorrelation of the time series, which are particularly pronounced at hourly granularity, affect and distort common estimators. After developing a controlled test environment with synthetic data that replicate key statistical properties of electricity demand, we show that not only the ordinary least square (OLS) estimator is inconsistent (due to simultaneity), but so is a regular instrumental variable (IV) regression (due to autocorrelation). Using wind as an instrument, as it is commonly done, may result in an estimate of the demand elasticity that is inflated by an order of magnitude. We visualize the reason for the Thams bias using causal graphs and show that its magnitude depends on the autocorrelation of both the instrument, and the dependent variable. We further incorporate and adapt two extensions of the IV estimation, conditional IV and nuisance IV, which have recently been proposed by Thams et al. (2022). We show that these extensions can identify the true short-term elasticity in a synthetic setting and are thus particularly promising for future empirical research in this field.}, language = {en} } @techreport{SanchezCanalesXuFusarBassinietal., type = {Working Paper}, author = {S{\´a}nchez Canales, Jorge and Xu, Alice Lixuan and Fusar Bassini, Chiara and Kaack, Lynn H. and Hirth, Lion}, title = {An empirical estimate of the electricity supply curve from market outcomes}, publisher = {arXiv}, doi = {10.48550/arXiv.2511.23068}, pages = {33}, abstract = {Researchers and electricity sector practitioners frequently require the supply curve of electricity markets and the price elasticity of supply for purposes such as price forecasting, policy analyses or market power assessment. It is common practice to construct supply curves from engineering data such as installed capacity and fuel prices. In this study, we propose a data-driven methodology to estimate the supply curve of electricity market empirically, i.e. from observed prices and quantities without further modeling assumptions. Due to the massive swings in fuel prices during the European energy crisis, a central task is detecting periods of stable supply curves. To this end, we implement two alternative clustering methods, one based on the fundamental drivers of electricity supply and the other directly on observed market outcomes. We apply our methods to the German electricity market between 2019 and 2024. We find that both approaches identify almost identical regimes shifts, supporting the idea of stable supply regimes stemming from stable drivers. Supply conditions are often stable for extended periods, but evolved rapidly during the energy crisis, triggering a rapid succession of regimes. Fuel prices were the dominant drivers of regime shifts, while conventional plant availability and the nuclear phase-out play a comparatively minor role. Our approach produces empirical supply curves suitable for causal inference and counterfactual analysis of market outcomes.}, language = {en} } @article{DertingerHirth, author = {Dertinger, Andrea and Hirth, Lion}, title = {Reforming the electric power industry in developing economies: Evidence on efficiency and electricity access outcomes}, series = {Energy Policy}, journal = {Energy Policy}, number = {139}, doi = {10.1016/j.enpol.2020.111348}, abstract = {Since the 1990s, many developing countries have restructured their electric power industry. Policies such as breaking up, commercializing and privatizing utilities, allowing for independent power producers, installing independent regulators, and introducing competitive wholesale markets were meant to improve the industry's efficiency and service quality. We exploit more than 30 years of data from over 100 countries to investigate the impact of power sector reforms on efficiency (represented by network losses) and access to electricity (represented by connection rates and residential power consumption). Crucially, reforms are likely to be endogenous with respect to sector performance: a crisis in electricity supply might well trigger reform efforts. We deal with endogeneity using reform activity in neighboring countries as an instrument. Our results suggest that reforms strongly and positively impact electricity access. According to our preferred specification, a full reform program would increase connection rates by 20 percentage points and per capita consumption by 62 percent: these are large effects that are stable across a range of robustness checks. Moreover, the effect of improving access is largest in South Asian countries. In contrast to previous studies, we do not find robust evidence to support the theory that reforms reduce network losses.}, language = {en} } @article{Hirth, author = {Hirth, Lion}, title = {Open Data for Electricity Modeling: Legal Aspects}, series = {Energy Strategy Reviews}, journal = {Energy Strategy Reviews}, number = {27}, doi = {10.1016/j.esr.2019.100433}, abstract = {Power system modeling is data intensive. In Europe, electricity system data is often available from sources such as statistical offices or system operators. However, it is often unclear if these data can be legally used for modeling, and in particular if such use infringes intellectual property rights. This article reviews the legal status of power system data, both as a guide for data users and for data publishers. It is based on interpretation of the law, a review of the secondary literature, an analysis of the licenses used by major data distributors, expert interviews, and a series of workshops. A core finding is that in many cases the legality of current practices is doubtful: in fact, it seems likely that modelers infringe intellectual property rights quite regularly. This is true for industry analysis but also academic researchers. A straightforward solution is open data - the idea that data can be freely used, modified, and shared by anyone for any purpose. To be open, it is not sufficient for data to be accessible free of cost, it must also come with an open data license, the most common types of which are also reviewed in this paper.}, language = {en} } @article{CloeteHirth, author = {Cloete, Schalk and Hirth, Lion}, title = {Flexible power and hydrogen production: Finding synergy between CCS and variable renewables}, series = {Energy}, volume = {192}, journal = {Energy}, doi = {10.1016/j.energy.2019.116671}, abstract = {The expansion of wind and solar power is creating a growing need for power system flexibility. Dispatchable power plants with CO2 capture and storage (CCS) offer flexibility with low CO2 emissions, but these plants become uneconomical at the low running hours implied by renewables-based power systems. To address this challenge, the novel gas switching reforming (GSR) plant was recently proposed. GSR can alternate between electricity and hydrogen production from natural gas, offering flexibility to the power system without reducing the utilization rate of the capital stock embodied in CCS infrastructure. This study assesses the interplay between GSR and variable renewables using a power system model, which optimizes investment and hourly dispatch of 13 different technologies. Results show that GSR brings substantial benefits relative to conventional CCS. At a CO2 price of €100/ton, inclusion of GSR increases the optimal wind and solar share by 50\%, lowers total system costs by 8\%, and reduces system emissions from 45 to 4 kgCO2/MWh. In addition, GSR produces clean hydrogen equivalent to about 90\% of total electricity demand, which can be used to decarbonize transport and industry. GSR could therefore become a key enabling technology for a decarbonization effort led by wind and solar power.}, language = {en} } @article{KhannaBaiocchiCallaghanetal., author = {Khanna, Tarun and Baiocchi, Giovanni and Callaghan, Max and Creutzig, Felix and Guias, Horia and Haddaway, Neal R. and Hirth, Lion and Javaid, Aneeque and Koch, Nicolas and Laukemper, Sonja and L{\"o}schel, Andreas and del Mar Zamora Dominguez, Maria and Minx, Jan C.}, title = {A multi-country meta-analysis on the role of behavioural change in reducing energy consumption and CO2 emissions in residential buildings}, series = {Nature Energy}, volume = {6}, journal = {Nature Energy}, doi = {10.1038/s41560-021-00866-x}, pages = {925 -- 932}, abstract = {Despite the importance of evaluating all mitigation options to inform policy decisions addressing climate change, a comprehensive analysis of household-scale interventions and their emissions reduction potential is missing. Here, we address this gap for interventions aimed at changing individual households' use of existing equipment, such as monetary incentives or feedback. We have performed a machine learning-assisted systematic review and meta-analysis to comparatively assess the effectiveness of these interventions in reducing energy demand in residential buildings. We extracted 360 individual effect sizes from 122 studies representing trials in 25 countries. Our meta-regression confirms that both monetary and non-monetary interventions reduce the energy consumption of households, but monetary incentives, of the sizes reported in the literature, tend to show on average a more pronounced effect. Deploying the right combinations of interventions increases the overall effectiveness. We have estimated a global carbon emissions reduction potential of 0.35 GtCO2 yr-1, although deploying the most effective packages of interventions could result in greater reduction. While modest, this potential should be viewed in conjunction with the need for de-risking mitigation pathways with energy-demand reductions.}, language = {en} } @techreport{RuhnauStieweMuesseletal., type = {Working Paper}, author = {Ruhnau, Oliver and Stiewe, Clemens and Muessel, Jarusch and Hirth, Lion}, title = {Gas demand in times of crisis. The response of German households and industry to the 2021/22 energy crisis}, pages = {8}, abstract = {Europe is in the midst of the most severe energy crisis in a generation, at the core of which is the continuously plummeting supply of Russian natural gas. With alternative supply options being limited, natural gas prices have surged. This paper empirically estimates the response of natural gas demand to the price increase, using data from Germany—the so far largest consumer of Russian natural gas. We identify the crisis response of small and large consumers separately, controlling for temperature, gas-fired power generation, and economic activity. For small consumers, including mostly households, we find a substantial demand reduction of 6\% from March onwards—most likely due to political and ethical considerations after the start of Russia's invasion of Ukraine. For industrial consumers, demand reductions started much earlier in August 2021, when wholesale prices for natural gas started to surge, with an average reduction of 11\%. We conclude that voluntary industrial demand response has played a significant role in coping with the energy crisis so far.}, language = {en} } @techreport{TiedemannStieweKratzkeetal., type = {Working Paper}, author = {Tiedemann, Silvana and Stiewe, Clemens and Kratzke, Corinna and Hirth, Lion and Jentsch, Mareike and Damm, Nicolai and Gerhardt, Norman and Pape, Carsten}, title = {Gebotszonenteilung: Auswirkungen auf den Marktwert der Erneuerbaren Energien im Jahr 2030}, publisher = {Kopernikus-Projekt Ariadne}, address = {Potsdam}, doi = {10.48485/pik.2024.002}, pages = {49}, abstract = {Eine Teilung des deutschen Marktgebietes w{\"u}rde die Marktwerte erneuerbarer Energien beeinflussen. Wind und Photovoltaik (PV) im S{\"u}den Deutschlands w{\"u}rden an Wert gewinnen, w{\"a}hrend Erneuerbare im Norden Erl{\"o}se einb{\"u}ßen w{\"u}rden. Bei einer auch zuk{\"u}nftig st{\"a}rkeren Konzentration von erneuerbaren Energien im Norden bedeutet dies insgesamt einen h{\"o}heren F{\"o}rderbedarf f{\"u}r PV - Wind w{\"a}re trotz niedriger Marktwerte in den meisten Regionen wirtschaftlich. Wenn eine regionale Steuerung erreicht werden soll, m{\"u}sste die auszuzahlende F{\"o}rderung f{\"u}r neue PV-Anlagen anhand des zonen{\"u}bergreifenden Referenzmarktwertes berechnet werden. Durchschnittliche B{\"o}rsenstrompreise w{\"u}rden durch eine Gebotszonenteilung im S{\"u}den Deutschlands leicht angehoben und im Norden gesenkt, die Effekte auf Endkundenpreise und damit verbundene Anreize zur Standortwahl von Industrieunternehmen sind allerdings als gering einzusch{\"a}tzen.}, language = {de} } @techreport{StieweXuEickeetal., type = {Working Paper}, author = {Stiewe, Clemens and Xu, Alice Lixuan and Eicke, Anselm and Hirth, Lion}, title = {Cross-border cannibalization: Spillover effects of wind and solar energy on interconnected European electricity markets}, publisher = {arXiv}, doi = {10.48550/arXiv.2405.17166}, pages = {25}, abstract = {The average revenue, or market value, of wind and solar energy tends to fall with increasing market shares, as is now evident across European electricity markets. At the same time, these markets have become more interconnected. In this paper, we empirically study the multiple cross-border effects on the value of renewable energy: on one hand, interconnection is a flexibility resource that allows to export energy when it is locally abundant, benefitting renewables. On the other hand, wind and solar radiation are correlated across space, so neighboring supply adds to the local one to depress domestic prices. We estimate both effects, using spatial panel regression on electricity market data from 2015 to 2023 from 30 European bidding zones. We find that domestic wind and solar value is not only depressed by domestic, but also by neighboring renewables expansion. The better interconnected a market is, the smaller the effect of domestic but the larger the effect of neighboring renewables. While wind value is stabilized by interconnection, solar value is not. If wind market share increases both at home and in neighboring markets by one percentage point, the value factor of wind energy is reduced by just above 1 percentage points. For solar, this number is almost 4 percentage points.}, language = {en} } @article{StieweXuEickeetal., author = {Stiewe, Clemens and Xu, Alice Lixuan and Eicke, Anselm and Hirth, Lion}, title = {Cross-border cannibalization: Spillover effects of wind and solar energy on interconnected European electricity markets}, series = {Energy Economics}, volume = {143}, journal = {Energy Economics}, publisher = {Elsevier BV}, issn = {0140-9883}, doi = {10.1016/j.eneco.2025.108251}, abstract = {The average per-MWh revenue, or market value, of wind and solar energy tends to fall with increasing market share, as is now evident across European electricity markets. At the same time, these markets are becoming more interconnected. In this paper, we empirically study cross-border effects on the value of renewable energy: On one hand, interconnection is a flexibility resource that allows to export energy when it is locally abundant, benefitting renewables. On the other hand, wind and solar patterns are correlated between countries, so neighboring supply adds to the local one to depress domestic prices. We estimate both effects, using spatial panel regression on electricity market data from 2015 to 2023 from 30 European bidding zones. We find that domestic wind and solar value is not only depressed by domestic, but also by neighboring renewables expansion. The better interconnected a market is, the smaller the effect of domestic but the larger the effect of neighboring renewables. While wind value is stabilized by interconnection, the data suggest that solar value is not. These results can be used to estimate the impact of simultaneous domestic and neighboring capacity expansion: If wind market share increases both at home and in neighboring markets by one percentage point, the value factor of wind energy is reduced by just above 1 percentage point. For solar, this number is almost 4 percentage points.}, language = {en} } @techreport{HirthTiedemannSchill, type = {Working Paper}, author = {Hirth, Lion and Tiedemann, Silvana and Schill, Wolf-Peter}, title = {Was sind eigentlich Netzentgelte?}, publisher = {Kopernikus-Projekt Ariadne}, address = {Potsdam}, doi = {10.48485/pik.2024.020}, pages = {8}, language = {de} } @article{EhrhartEickeHirthetal., author = {Ehrhart, Karl-Martin and Eicke, Anselm and Hirth, Lion and Ocker, Fabian and Ott, Marion and Schlecht, Ingmar and Wang, Runxi}, title = {Congestion Management Games in Electricity Markets}, series = {The Energy Journal}, volume = {47}, journal = {The Energy Journal}, number = {1}, doi = {10.1177/01956574251365606}, pages = {77 -- 108}, abstract = {This paper proposes a game-theoretic model to analyze the strategic behavior of inc-dec gaming in market-based congestion management (redispatch). We extend existing models by considering incomplete information about competitors' costs and a finite set of providers. We find that these extensions do not dissolve inc-dec gaming, which already occurs in our setup of two regions. We also benchmark market-based redispatch against grid investment, cost-based redispatch, and the Vickrey-Clarke-Groves mechanism. The comparison highlights a significant inefficiency of market-based redispatch and inflated redispatch payments. Finally, we study seven variations of our basic model to assess whether different market fundamentals or market design changes mitigate inc-dec gaming. None of these variations eliminate inc-dec gaming entirely.}, language = {en} }