New Scymnus (Pullus)-species (Coleoptera, Coccinellidae) from Uganda

Three new species of Ugandan Kibale forest are described, figured and compared with closely related species: Scymnus (Pullus) auritoides sp. n., S. (Pullus) fumosipennis sp. n. and S. (Pullus) siphonofissus sp. n. S. (Pullus) nigropectus Mader is redescribed, based on new material. New synonyms: S. mundus Mader is a younger synonym of S. nigrosellatus Mader and S. couturieri Chazeau is a synonym of S. majeri Fürsch

Die afrikanischen Arten der Scymnus fronfalis-Gruppe (Coleoptera, Coccinellidae)

This article is mainly based on the collections of M. Nummelin in Kibale forest, Uganda. The new species Scymnus danielssoni, S. kibaliensis and S. nummelini are described and compared with the closely related S. capicola, S. cyclicus, S. declaratus, S. demeteri, S. kibonotensis, S. patruelis , S. scapuliþrus and S. simulans. S. congoanus Mader is a new synonym of S. kibonotensis Weise. Male genitals and outlines of the species are figured and a pictorial key is given

The costs of electricity systems with a high share of fluctuating renewables - a stochastic investment and dispatch optimization model for Europe

Renewable energies are meant to produce a large share of the future electricity demand. However, the availability of wind and solar power depends on local weather conditions and therefore weather characteristics must be considered when optimizing the future electricity mix. In this article we analyze the impact of the stochastic availability of wind and solar energy on the cost-minimal power plant mix and the related total system costs. To determine optimal conventional, renewable and storage capacities for different shares of renewables, we apply a stochastic investment and dispatch optimization model to the European electricity market. The model considers stochastic feed-in structures and full load hours of wind and solar technologies and different correlations between regions and technologies. Key findings include the overestimation of fluctuating renewables and underestimation of total system costs compared to deterministic investment and dispatch models. Furthermore, solar technologies are - relative to wind turbines - underestimated when neglecting negative correlations between wind speeds and solar radiation.Stochastic programming; electricity; renewable energy

Promotion of electricity from renewable energy in Europe post 2020: The economic benefits of cooperation

In Europe, the availability of renewable energies, especially from sun and wind, differs significantly across regions. Consequently, cooperation in the deployment of renewable energy among European countries potentially yields substantial efficiency gains. However, in order to achieve the 2020 renewable energy targets for electricity, Member States of the European Union almost purely rely on domestic production. For the period after 2020, a European renewable energy target has not yet been defined, but decarbonization pathways outlined in the Roadmap of the European Commission include renewable energy shares of electricity generation to be 50-60% by 2030. Therefore, we analyze the benefits of cooperation compared to continuing with national renewable energy support after 2020. We use a large-scale dynamic investment and dispatch model of the European electricity system and find that compared to a 2030 CO2 -only target (-40% compared to 1990 emission levels), electricity system costs increase by 5 to 7% when a European-wide renewable energy target for electricity generation (of around 55%) is additionally implemented. However, these additional costs are lower by 41 to 45% compared to the additional electricity system costs which would arise if the renewable energy target was reached through national support systems (without cooperation). Furthermore, we find that the cooperation gains (i.e., the cost reduction achieved by cooperation) are quite robust: They decrease only slightly when interconnectors are not further extended (compared to today) and depend only slightly on assumptions about investment cost developments of renewable energy technologies. With regard to the practical implementation of cooperation, however, unclear administrative issues and questions concerning the fair sharing of costs and benefits between the Member States represent major obstacles that need to be tackled in order to reach renewable energy targets at the lowest costs possible

The economic value of storage in renewable power systems - the case of thermal energy storage in concentrating solar plants

In this article we analyze the value of thermal energy storages in concentrated solar plants depending on the electricity generation mix. To determine the value from a system integrated view we model the whole electricty generation market of the Iberian Peninsula. Key findings for thermal energy storage units in concentrated solar plants include an increasing value in electricity systems with higher shares of fluctuating renewable generation and a potentially significant role in a transformation to a primarily renewable based electricity system. Due to the relatively high investment costs concentrated solar power plants with or without thermal energy storages are not cost efficient in todays electricity markets. However, expected cost reductions due to learning curve effects and higher fluctuating renewable generation may lead to a comparative cost advantage of concentrated solar power plants with thermal energy storages compared to other renewable technologies.Fluctuating renewables; value of storage; concentrated solar power; power plant optimization

The costs of electricity systems with a high share of fluctuating renewables - a stochastic investment and dispatch optimization model for Europe

Renewable energies are meant to produce a large share of the future electricity demand. However, the availability of wind and solar power depends on local weather conditions and therefore weather characteristics must be considered when optimizing the future electricity mix. In this article we analyze the impact of the stochastic availability of wind and solar energy on the cost-minimal power plant mix and the related total system costs. To determine optimal conventional, renewable and storage capacities for different shares of renewables, we apply a stochastic investment and dispatch optimization model to the European electricity market. The model considers stochastic feed-in structures and full load hours of wind and solar technologies and different correlations between regions and technologies. Key findings include the overestimation of fluctuating renewables and underestimation of total system costs compared to deterministic investment and dispatch models. Furthermore, solar technologies are - relative to wind turbines - underestimated when neglecting negative correlations between wind speeds and solar radiation

Scenarios for an Energy Policy Concept of the German Government

In this working paper we demonstrate how challenging greenhouse gas reduction targets of up to 95% until 2050 can be achieved in the German electricity sector. In the analysis, we focus on the main requirements to reach such challenging targets. To account for interdependencies between the electricity market and the rest of the economy, different models were used to account for feedback loops with all other sectors. We include scenarios with different runtimes and retrofit costs for existing nuclear plants to determine the effects of a prolongation of nuclear power plants in Germany. Key findings for the electricity sector include the importance of a European-wide coordinated electricity grid extension and the exploitation of regional comparative cost effects for renewable sites. Due to political restrictions, nuclear energy will not be available in Germany in 2050. However, the nuclear life time extension has a positive impact on end consumer electricity prices as well as economic growth in the medium term, if retrofit costs do not exceed certain limits.Roadmap 2050; GHG reduction; renewable energies; carbon capture and storage; power plant fleet optimization

Der Merit-Order-Effekt der erneuerbaren Energien - Analyse der kurzen und langen Frist

Unter dem Merit-Order-Effekt (M-O-E) der erneuerbaren Energien (EE) wird deren preissenkende Wirkung auf die Strompreise auf Großhandelsebene (Börsenpreise) verstanden. Sowohl die Höhe des Merit-Order-Effekts in der kurzen und der langen Frist als auch dessen volkswirtschaftliche Bedeutung ist umstritten. In diesem Artikel analysieren wir zunächst, durch welche Faktoren Preiseeffekte erneuerbarer Energien in der kurzen Frist bestimmt werden, unter welchen Bedingungen Preiseffekte in einem theoretischen langfristigen Gleichgewicht möglich sind und welche Preiseffekte in der Realität durch Unsicherheiten und dynamische Anpassungsprozesse entstehen. In einem zweiten Teil berechnen wir mit einem Optimierungsmodell des europäischen Strommarkts den M-O-E für Deutschland bis 2030. Hierbei berücksichtigen wir im Unterschied zu bestehenden Berechnungen zwei wichtige Determinanten des M-O-E endogen: Anpassungsprozesse des Kraftwerksparks sowie Stromaustauschmöglichkeiten mit dem europäischen Ausland

German Nuclear Policy Reconsidered: Implications for the Electricity Market

In the aftermath of the nuclear catastrophe in Fukushima, German nuclear policy has been reconsidered. This paper demonstrates the economic effects of an accelerated nuclear phase-out on the German electricity generation sector. A detailed optimization model for European electricity markets is used to analyze two scenarios with different lifetimes for nuclear plants (phase-out vs. prolongation). Based on political targets, both scenarios assume significant electricity demand reductions and a high share of generation from renewable energy sources in Germany. Our principal findings are: First, nuclear capacities are mainly replaced by longer lifetimes of existing coal-fired plants and the construction of new gas-fired plants. Second, fossil fuel-based generation and power imports increase, while power exports are reduced in response to the lower nuclear generation. Third, despite the increased fossil generation, challenging climate protection goals can still be achieved within the framework of the considered scenarios. Finally, system costs and electricity prices are clearly higher. We conclude that the generation sector can generally cope with an accelerated nuclear phase-out under the given assumptions. Yet, we emphasize that such a policy requires a substantial and costly transformation of the supply and the demand side.Nuclear policy; climate protection; renewable energy; electricity market modeling

Optimization of power plant investments under uncertain renewable energy development paths - A multistage stochastic programming approach

Electricity generation from renewable energy sources (RES-E) is supposed to increase signi ficantly within the coming decades. However, uncertainty about the progress of necessary infrastructure investments, public acceptance and cost developments of renewable energies renders the achievement of political plans uncertain. Implementation risks of renewable energy targets are challenging for investment planning, because different RES-E shares fundamentally change the optimal mix of dispatchable power plants. Speci cally, uncertain future RES-E deployment paths induce uncertainty about the steepness of the residual load duration curve and the hourly residual load structure. In this paper, we show how uncertain future RES-E penetrations impact the electricity system and try to quantify effects for the Central European power market. We use a multi-stage stochastic investment and dispatch model to analyze effects on investment choices, electricity generation and system costs. Our main findings include that the uncertain achievement of RES-E targets significantly effects optimal investment decisions. First, a higher share of technologies with a medium capital/operating cost ratio is cost-efficient. Second, the value of storage units in systems with high RES-E penetrations might decrease. Third, in the case of the Central European power market, costs induced by the implementation risk of renewable energies seem to be rather small compared to total system costs