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While high renewable electricity targets are feasible under current climatic conditions, planning the power sector from a long-term perspective requires great precaution, given the strong dependency of renewable energy potential on climate and potential future changes. Power balance optimization modelling is a powerful tool for adequate power system (contingency) planning, and informed decision making in future perspective. This is demonstrated based on a case study of Suriname, considering scenario simulations and impact assessments for the 2030–2040 time horizon, for multiple load and climate projections. The recently developed REVUB modelling approach is utilized, which facilitates hourly-to-multiannual simulations, the latter being important for inter-annual variability assessments, and key for climate impact studies. Our results show that Suriname has an optimized renewable electricity share potential ranging from 50% to 90% under the considered future scenarios based on complementary exploitation of hydro, wind and solar power resources.

Emergency service workers are exposed to many stressors during their work that can lead to pressure, strain and other negative consequences. If they recover after traumatic events and do not show long-term negative consequences, this is referred to as resilience. Certain individual, institutional, and social resources and strategies are key factors that influence people's ability to cope successfully. However, those specific resources and coping strategies that can enhance resilience have not yet been studied in detail among emergency service workers, even though they are exposed to various impacts on a daily basis. The present study investigated a total of 774 emergency service workers operating in Germany. It used well-established questionnaires designed to investigate resources, coping styles, and resilience, and multiple linear regression analysis was performed on the responses. The results indicate that emergency service workers are exposed to stressors, especially on the institutional level. However, they possess personal, social, and institutional resources and coping strategies that enhance resilience. Personal resources like self-efficacy and ambiguity tolerance prove to be the strongest predictors of emergency service workers’ resilience. Problem-focused coping is found to increase resilience, whereas emotion-oriented coping seems to be related negatively. Measures that increase resilience should be included in education and training, as is discussed in the practical implications. Training materials such as learning games support the development of ambiguity tolerance and self-efficacy of emergency service personnel while stress tests for organizations enhance the operating capabilities of emergency organizations even.

Aligning development and climate goals means Africa’s energy systems will be based on clean energy technologies in the long term, but pathways to get there are uncertain and variable across countries. Although current debates about natural gas and renewables in Africa are heated, they largely ignore the substantial context specificity of the starting points, development objectives and uncertainties of each African country’s energy system trajectory. Here we—an interdisciplinary and majority African group of authors—highlight that each country faces a distinct solution space and set of uncertainties for using renewables or fossil fuels to meet its development objectives. For example, Ethiopia is headed for an accelerated green-growth pathway, but Mozambique is at a crossroads of natural gas expansion with implicit large-scale technological, economic, financial and social risks and uncertainties. We provide geopolitical, policy, finance and research recommendations to create firm country-specific evidence to identify adequate energy system pathways for development and to enable their implementation.

Alongside its immediate consequences for physical health, the current Coronavirus pandemic and the associated containment measures have led to multiple psychosocial consequences for the population. While virus containment is the main motive of crisis management, there is, so far, little evidence on how crisis management actors consider findings about the psychosocial state of the German population. This paper therefore examines the role of psychosocial consequences within the work of crisis management organizations during the Corona pandemic in Germany. Against the theoretical background of the sensemaking concept, 14 qualitative interviews were conducted with decision-makers from municipal and state administrations, public health departments, aid organizations, and critical infrastructure organizations. Our results indicate that crisis managers perceive aspects related to the psychosocial situation as relevant, but in a very selective way. They use different and often non-scientific sources to acquire knowledge about the psychosocial consequences. In sum, these aspects do not play a major role in decision-making processes. We argue that the perception and processing of psychosocial consequences depend in particular on the organizational context such as goals, plausibility assumptions, identity conceptions, and problem frames. In order to extend theoretical models of psychosocial crisis management, more detailed knowledge of sensemaking processes in crisis management organizations is necessary.

Purpose of review This review paper assesses recent scientific findings around the integration of variable renewable electricity (VRE) sources, mostly solar PV and wind power, on power grids across Africa, in the context of expanding electricity access while ensuring low costs and reducing fossil fuel emissions. Recent findings In this context, significant research attention has been given to increased cross-border transmission infrastructure between African countries to harness the spatiotemporal complementarities between renewable electricity resources, as well as to storage options, such as battery storage and power-to-gas. Summary Much of the recent, model-based literature suggests that a combination of increased interconnections in and between Africa’s power pools, leveraging spatiotemporal complementarities between solar PV, wind and hydropower, as well as a large-scale deployment of storage options could help African countries meet their burgeoning power demand with largely decarbonized electricity supply.

A new model, REVUB-Light, an extended modelling approach for the recently developed “Renewable Energy Variability Upscaling and Balancing” (REVUB) model, is highlighted in this study for its relatively simple and effective parameterization for power balance optimization simulations, considering high Intermittent Renewable Energy integration. We demonstrate the effective use of the REVUB-Light model, considering a study for Suriname. The results for different cases are compared to those of the REVUB model, previously used for similar assessments for Suriname. Following distinct optimization procedures, our results confirm the REVUB model findings, i.e., a highly complementary role for wind energy, with up to 20–30% feed-in potential, based on the assumed (currently most probable) hydrological and wind regimes. The REVUB-Light model is validated based on actual operational data, enabling assessments of the potential real world response, and the benefits of flexible (optimized) operational regimes, underlining its potential for renewable energy modelling. It is further shown that Suriname has potential for (near) 100% renewable energy supply, for the mid-term horizon (2030), if additional hydropower potential is developed in combination with hydro-supported wind energy. Overall, the parsimonious approach of REVUB-Light proves to be a reliable modelling tool, and facilitates general usability by “non-experts” such as policymakers.

Ethiopia, Sudan and Egypt are currently embroiled in a politically charged conflict that surrounds the soon-to-be-completed Grand Ethiopian Renaissance Dam (GERD), with Ethiopia’s energy objectives purportedly conflicting with the water needs in Sudan and Egypt. Here we show that the multiple political and environmental challenges that surround GERD could be mitigated by explicitly coupling its operation to variable solar and wind power, which would create an incentive for Ethiopia to retain a seasonality in the Blue Nile flow. We found that this could deliver fivefold benefits across the three countries: decarbonizing power generation in the Eastern Africa Power Pool; allowing compliance with Sudan’s environmental flow needs; optimizing GERD’s infrastructure use; harmonizing the yearly refilling schedules of GERD and Egypt’s High Aswan Dam; and supporting a strong diversification of Ethiopian power generation for domestic use and for Eastern Africa Power Pool exports. These results argue for an explicit integration of complementary hydro, solar and wind power strategies in GERD operation and Eastern Africa Power Pool expansion planning. The Grand Ethiopian Renaissance Dam will be hugely beneficial to Ethiopia, but has raised tensions with neighbouring countries that rely on flow from the Blue Nile. Sterl et al. present scenarios for dam operation coupled with solar and wind power generation that could mitigate some of these concerns.

Understanding and quantifying land management impacts on local climate is important for distinguishing between the effects of land management and large-scale climate forcings. This study for the first time explicitly considers the radiative forcing resulting from realistic land management and offers new insights into the local land surface response to land management. Regression-based trend analysis is applied to observations and present-day ensemble simulations with the Community Earth System Model (CESM) version 1.2.2 to assess the impact of irrigation and conservation agriculture (CA) on warming trends using an approach that is less sensitive to temperature extremes. At the regional scale, an irrigation- and CA-induced acceleration of the annual mean near-surface air temperature (T2m) warming trends and the annual maximum daytime temperature (TXx) warming trends were evident. Estimation of the impact of irrigation and CA on the spatial average of the warming trends indicated that irrigation and CA have a pulse cooling effect on T2m and TXx, after which the warming trends increase at a greater rate than the control simulations. This differed at the local (subgrid) scale under irrigation where surface temperature cooling and the dampening of warming trends were both evident. As the local surface warming trends, in contrast to regional trends, do not account for atmospheric (water vapour) feedbacks, their dampening confirms the importance of atmospheric feedbacks (water vapour forcing) in explaining the enhanced regional trends. At the land surface, the positive radiative forcing signal arising from enhanced atmospheric water vapour is too weak to offset the local cooling from the irrigation-induced increase in the evaporative fraction. Our results underline that agricultural management has complex and non-negligible impacts on the local climate and highlight the need to evaluate the representation of land management in global climate models using climate models of higher resolution., Earth System Dynamics, 13 (1), ISSN:2190-4987, ISSN:2190-4979

The modelling of electricity systems with substantial shares of renewable resources, such as solar power, wind power and hydropower, requires datasets on renewable resource profiles with high spatiotemporal resolution to be made available to the energy modelling community. Whereas such resources exist for solar power and wind power profiles on diurnal and seasonal scales across all continents, this is not yet the case for hydropower. Here, we present a newly developed open-access African hydropower atlas, containing seasonal hydropower generation profiles for nearly all existing and several hundred future hydropower plants on the African continent. The atlas builds on continental-scale hydrological modelling in combination with detailed technical databases of hydropower plant characteristics and can facilitate modelling of power systems across Africa.

The Caribbean nation of Suriname has historically depended on a mix of hydropower and oil-based fossil fuels for meeting electricity needs. Continued reliance on fossil fuels poses challenges both for climate change mitigation and for energy security. This paper explores the potential for increasing the share of renewables in Suriname's electricity mix, with a special focus on the complementary role of existing hydropower and future wind power infrastructure. We show that these resources have great synergetic potential for displacing fossil fuel-based power generation. Flexible operation of the Afobaka hydropower plant, newly in full possession of Suriname, allows significant wind power integration without violating grid stability and associated power quality requirements. Considering the trade-off between displacing expensive fossil fuels and limiting wind power curtailment on Suriname's island-like grid, our results suggest that integrating wind power in the Surinamese electricity mix is economically advantageous up to a share of 20–30%, independently of near-term demand growth. These results have wider relevance for climate policy in various Caribbean countries and other island states with existing hydropower infrastructure and substantial wind/solar power potential, for which this study fills an important literature gap.

Moving from fossil fuel-based electricity generation to renewable electricity generation is at the heart of current developments in power sectors worldwide. In this context, synergy assessment between renewable electricity sources is of great significance for local and regional power planning. Here we use synergy metrics (stability coefficient (Cstab) and normalised Pearson correlation coefficient (r) to a state-of-the-art reanalysis product from 2011–2020 to preliminarily assess solar-wind synergies globally on diurnal and seasonal time scales assuming equal installed capacities of solar and wind hybrid system. Our results suggest that medium-to-good diurnal and seasonal complementarities between solar photovoltaic and wind power potential are the norm, rather than the exception, which could help many countries in achieving balanced power mixes based on renewable resources. Our results also suggest that many regions in the tropics and sub tropics may need to explore synergic benefits of other renewables in addition to solar power. An open-access application is now available on the European Copernicus cloud to explore solar and wind synergies on diurnal and seasonal time scales worldwide.

In sub-Saharan Africa, 160 million grid-connected electricity consumers live in countries where hydropower accounts for over 50% of total power supply. A warmer climate with more frequent and intense extremes could result in supply reliability issues. Here, (i) a robust framework to highlight the interdependencies between hydropower, water availability, and climate change is proposed, (ii) the state-of-the art literature on the projected impacts of climate change on hydropower in sub-Saharan Africa is reviewed, and (iii) supporting evidence on past trends and current pathways of power mix diversification, drought incidence, and climate change projections is provided. We find that only few countries have pursued a diversification strategy away from hydropower over the last three decades, while others' expansion plans will reinforce the dependency. This will occur irrespective of the fact that some of the largest river basins have experienced a significant drying during the last century. Agreement is found on likely positive impacts of climate change on East Africa's hydropower potential, negative impacts in West and Southern Africa, and substantial uncertainty in Central Africa. Irrespective of the absolute change in gross technical potential, more frequent and intense extremes are projected. One possible paradigm to increase resilience and fulfil the pledges of the Paris Agreement is a synergetic planning and management of hydropower and variable renewables.

West African countries' energy and climate policies show a pronounced focus on decarbonising power supply through renewable electricity (RE) generation. In particular, most West African states explicitly focus on hybrid mixes of variable renewable power sources—solar, wind and hydropower—in their targets for the electricity sector. Hydropower, the main current RE resource in West Africa, is strongly sensitive to monsoon rainfall variability, which has led to power crises in the past. Therefore, solar and wind power could play a stronger role in the future as countries move to power systems with high shares of RE. Considering the policy focus on diversified RE portfolios, there is a strong need to provide climate services for assessing how these resources could function together in a power mix. In this study, climate data from the state-of-the-art ERA5 reanalysis is used to assess the synergies of solar photovoltaic (PV) and wind power potential in West Africa at hourly resolution. A new metric, the stability coefficient C_stab, is developed to quantify the synergies of solar PV and wind power for achieving a balanced power output and limiting storage needs. Using this metric, it is demonstrated that there is potential for exploiting hybrid solar/wind power in a larger area of West Africa, covering more important centers of population and closer to existing grid structures, than would be suggested by average maps of solar and wind resource availability or capacity factor for the region. The results of this study highlight why multi-scale temporal synergies of power mixes should be considered in RE system planning from the start. ispartof: Environmental Research Letters vol:13 issue:9 pages:1-11 status: published

A drop of water that freezes from the outside-in presents an intriguing problem: the expansion of water upon freezing is incompatible with the self-confinement by a rigid ice shell. Using high-speed imaging we show that this conundrum is resolved through an intermittent fracturing of the brittle ice shell and cavitation in the enclosed liquid, culminating in an explosion of the partially frozen droplet. We propose a basic model to elucidate the interplay between a steady build-up of stresses and their fast release. The model reveals that for millimetric droplets the fragment velocities upon explosion are independent of the droplet size and only depend on material properties (such as the tensile stress of the ice and the bulk modulus of water). For small (sub-millimetric) droplets, on the other hand, surface tension starts to play a role. In this regime we predict that water droplets with radii below 50 micrometer are unlikely to explode at all. We expect our findings to be relevant in the modeling of freezing cloud and rain droplets., Comment: 5 pages, 3 figures

German Abstract: In dieser Arbeit werden Bestimmungsfaktoren der Einkommensentwicklung in Deutschland zwischen Personen mit und ohne Migrationshintergrund mittels des Sozio-oekonomischen Panels (SOEP) untersucht. Nach theoretischer Auseinandersetzung mit den Determinanten, gegliedert nach soziodemografischen, individuellen, sozialen und arbeitsmarktspezifischen Merkmalen, wird der Effekt jener auf die abhangige Variable des logarithmierten Bruttolohns pro Stunde sowohl bivariat als auch unter Einfluss moglicher Drittvariablen mittels einer Random-Effects-Panelregression (RE) gepruft. Die Ergebnisse sind verschieden. Obwohl die meisten Variablen bivariat signifikant mit Einkommen korrelieren, sind einige unter Kontrolle aller anderen Variablen nicht mehr statistisch signifikant. Humankapital- und arbeitsmarktspezifische Zusammenhange bleiben jedoch robust. English Abstract: This thesis deals with determinants of income, compared between persons with and without any migration status in Germany using the German Socio-economic Panel (SOEP). After explaining theoretical relations of these sociodemographic, individual, social and labour market-related determinants, both a bivariate analysis and random-effects-regression (RE) are conducted with the logarithm of gross income per hour as dependent variable and those determinants mentioned above. The results are different. Although most of determinants are significantly correlated with income, some of them are not significant any more when controlling for all variables in a panel model. Nevertheless, aspects of the human capital theory and labour market-related determinants remain robust.

In this paper, we present results from an experimental study into turbulent Rayleigh-Bénard convection forced externally by periodically modulated unidirectional rotation rates. We find that the azimuthal rotation velocity θ(t) and thermal amplitude δ(t) of the large-scale circulation (LSC) are modulated by the forcing, exhibiting a variety of dynamics including increasing phase delays and a resonant peak in the amplitude of θ(t). We also focus on the influence of modulated rotation rates on the frequency of occurrence η of stochastic cessation or reorientation events, and on the interplay between such events and the periodically modulated response of θ(t). Here we identify a mechanism by which η can be amplified by the modulated response, and these normally stochastic events can occur with high regularity. We provide a modeling framework that explains the observed amplitude and phase responses, and we extend this approach to make predictions for the occurrence of cessation events and the probability distributions of θ(t) and δ(t) during different phases of a modulation cycle, based on an adiabatic approach that treats each phase separately. Last, we show that such periodic forcing has consequences beyond influencing LSC dynamics, by investigating how it can modify the heat transport even under conditions where the Ekman pumping effect is predominant and strong enhancement of heat transport occurs. We identify phase and amplitude responses of the heat transport, and we show how increased modulations influence the average Nusselt number.

We present measurements of the azimuthal rotation velocity $\dot{{\it\theta}}(t)$ and thermal amplitude ${\it\delta}(t)$ of the large-scale circulation in turbulent Rayleigh–Bénard convection with modulated rotation. Both $\dot{{\it\theta}}(t)$ and ${\it\delta}(t)$ exhibit clear oscillations at the modulation frequency ${\it\omega}$. Fluid acceleration driven by oscillating Coriolis force causes an increasing phase lag in $\dot{{\it\theta}}(t)$ when ${\it\omega}$ increases. The applied modulation produces oscillatory boundary layers and the resulting time-varying viscous drag modifies ${\it\delta}(t)$ periodically. Oscillation of $\dot{{\it\theta}}(t)$ with maximum amplitude occurs at a finite modulation frequency ${\it\omega}^{\ast }$. Such a resonance-like phenomenon is interpreted as a result of optimal coupling of ${\it\delta}(t)$ to the modulated rotation velocity. We show that an extended large-scale circulation model with a relaxation time for ${\it\delta}(t)$ in response to the modulated rotation provides predictions in close agreement with the experimental results.

The worldwide growth of variable renewable power sources necessitates power system flexibility to safeguard the reliability of electricity supply. Yet today, flexibility is mostly delivered by fossil fuel power plants. Hydropower can be a renewable alternative source of flexibility, but only if operated according to adequate strategies considering hourly-to-decadal and local-to-regional energy and water needs. Here, we present a new model to investigate hydro–solar–wind complementarities across these scales. We demonstrate that smart management of present and future hydropower plants in West Africa can support substantial grid integration of solar and wind power, limiting natural gas consumption while avoiding ecologically harmful hydropower overexploitation. We show that pooling regional resources and planning transmission grid expansion according to spatiotemporal hydro–solar–wind synergies are crucial for optimally exploiting West Africa’s renewable potential. By 2030, renewable electricity in such a regional power pool, with solar and wind contributing about 50%, could be at least 10% cheaper than electricity from natural gas. A smart management of hydropower, combined with solar and wind energy, can provide the flexibility needed to power West Africa and at cheaper cost than using natural gas, according to a simulation model.

This article reviews climate change mitigation policies implemented in five major emitting economies: China, the European Union, India, Japan and the United States. It analyses their historical performance in terms of energy system and greenhouse gas emissions indicators. In cases where policies aim to reduce future emissions, their target performance levels are assessed. The review centres on the sectors of electricity generation, passenger vehicles, freight transport, forestry, industry, buildings, agriculture, and oil and gas production. Most focus countries have implemented successful policies for renewable energy, fuel efficiency, electrification of passenger vehicles, and forestry. For other sectors, information is limited or very heterogeneous (e.g. buildings, appliances, agriculture) or there are few comprehensive policies in place (e.g. industry). The article further presents an explorative emissions scenario developed under the assumption that all countries will replicate both the observed trends in sector-level indicators and the trends that policies for future emissions reductions aspire to achieve. It shows that the global replication of sector progress would reduce greenhouse gas emissions by 2030 by about 20% compared to a current policies scenario. All countries analysed would overachieve the emissions reduction targets in their post-2020 climate targets. However, the resulting reduction in global emissions by 2030 would still not be sufficient to keep the world on track for a global cost-effective pathway that keeps temperature increase below 2°C. The findings of this study emphasise the need for transformative policies to keep the Paris Agreement temperature limit within reach.