• Energy Research
• 7. Clean energy close
• 3. Good health close
• DE close
• University of Freiburg: FreiDok close

An aluminium battery using an organic redox polymer as a positive electrode material delivers high reversible specific capacities at fast C-rates.

Solar Energy Materials and Solar Cells, 116 + (2013) 176-181. doi:10.1016/j.solmat.2013.04.019

AbstractThermal oxides are commonly used for the surface passivation of high‐efficiency silicon solar cells from mono‐ and multicrystalline silicon and have led to the highest conversion efficiencies reported so far. In order to improve the cost‐effectiveness of the oxidation process, a wet oxidation in steam ambience is applied and experimentally compared to a standard dry oxidation. The processes yield identical physical properties of the oxide. The front contact is created using a screen‐printing process of a hotmelt silver paste in combination with light‐induced silver plating. The contact formation on the front requires a short high‐temperature firing process, therefore the thermal stability of the rear surface passivation is very important. The surface recombination velocity of the fired oxide is experimentally determined to be below S ≤ 38 cm/s after annealing with a thin layer of evaporated aluminium on top. Monocrystalline solar cells are produced and 19·3% efficiency is obtained as best value on 4 cm2 cell area. Simulations show the potential of the developed process to approach 20% efficiency. Copyright © 2008 John Wiley & Sons, Ltd.

The transformation of the present energy system into a sustainable one is discussed worldwide. This is also mirrored in a vivid debate in the scientific literature [1–3]. Self-sufficiency attained with the help of electricity, heat, and fuel from renewable energy (RE) in combination with energy saving is seen as one way to establish a sustainable energy system, e.g., [4,5]. Many communities and regions in different countries are facing the challenge of such a transformation of their energy system, and have taken up the objective of achieving energy self-sufficiency through the use of renewables [4,6–8]. [...]

This paper presents the results of the second edition of the Wind Farm Layout Optimization Competition, which was held at the 22nd Genetic and Evolutionary Computation COnference (GECCO) in 2015. During this competition, competitors were tasked with optimizing the layouts of five generated wind farms based on a simplified cost of energy evaluation function of the wind farm layouts. Online and offline APIs were implemented in C++, Java, Matlab and Python for this competition to offer a common framework for the competitors. The top four approaches out of eight participating teams are presented in this paper and their results are compared. All of the competitors' algorithms use evolutionary computation, the research field of the conference at which the competition was held. Competitors were able to downscale the optimization problem size (number of parameters) by casting the wind farm layout problem as a geometric optimization problem. This strongly reduces the number of evaluations (limited in the scope of this competition) with extremely promising results.

Abstract Local energy markets are a promising way to involve prosumers in the electricity system and activate demand-side flexibility. In this paper, we develop a modeling framework consisting of an optimization for prosumer home energy management systems embedded in a local energy market simulation. To enable an integrated assessment, the local market is linked to a central spot market. For each prosumer, we consider the individual flexibility potential, home storage systems, and demand response of electric vehicles. Using this model, we analyze the costs and benefits of a local market for prosumers in an energy system with a high share of renewable energy. We compare the systemic effects and the potential economic benefits of this local market for prosumers to pure self-consumption and prosumer participation in a central spot market. Applying our model to a case study of 480 prosumers, we show that a system including a local market is beneficial compared to self-consumption from a systemic perspective. However, allowing prosumers to participate directly in a central spot market is more profitable and facilitates the system integration of renewables.