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In this contribution, we discuss the implementation of a novel microelectromechanical-systems (MEMS)-based energy harvester (EH) concept within the technology platform available at the ISAS Institute (TU Vienna, Austria). The device, already presented by the authors, exploits the piezoelectric effect to convert environmental vibrations energy into electricity, and presents multiple resonant modes in the frequency range of interest (i.e. below 10 kHz). The experimental characterisation of a sputter deposited aluminium nitride piezoelectric thin-film layer is reported, leading to the extraction of material properties parameters. Such values are then incorporated in the finite element method model of the EH, implemented in Ansys Workbench (TM), in order to get reasonable estimates of the converted power levels achievable by the proposed device solution. Multiphysics simulations indicate that extracted power values in the range of several mu W can be addressed by the EH-MEMS concept when subjected to mechanical vibrations up to 10 kHz, operating in closed-loop conditions (i.e. piezoelectric generator connected to a 100 k Omega resistive load). This represents an encouraging result, opening up the floor to exploitations of the proposed EH-MEMS device in the field of wireless sensor networks and zero-power sensing nodes.

Computers can reduce their power consumption by decreasing their speed using Dynamic Voltage and Frequency Scaling (DVFS). A form of DVFS for multicore processors is global DVFS, where the voltage and clock frequency is shared among all processor cores. Because global DVFS is efficient and cheap to implement, it is used in modern multicore processors like the IBM Power 7, ARM Cortex A9 and NVIDIA Tegra 2. This theory oriented paper discusses energy optimal DVFS algorithms for such processors. There are no known provably optimal algorithms that minimize the energy consumption of nontrivial real-time applications on a global DVFS system. Such algorithms only exist for single core systems, or for simpler application models. While many DVFS algorithms focus on tasks, this theoretical study is conceptually different and focuses on the amount of parallelism. We provide a transformation from a multicore problem to a single core problem, by using the amount of parallelism of an application. Then existing single core algorithms can be used to find the optimal solution. Furthermore, we extend an existing single core algorithm such that it takes static power into account.

The German Energiewende is a leading example of an attempt to transition the energy system of an industrialised country from centralised fossil and nuclear fuels to decentralised renewables. In recent years, the Energiewende has come under significant pressure. The fast growth of renewables owned by decentralised actors posed an existential economic threat to the large energy utilities, whose profits and share values crashed. The changes made in the Renewable Energy Act in 2014 and 2016 sought to slow the growth of renewables and have concentrated subsidies on large utilities. Meanwhile, Germany is still clearing space for new open-cut lignite mines. Why is Germany still into coal? In this paper, we analyse the German Energiewende as a contested socio-technical process. We argue that path dependence and carbon lock-in are hindering and slowing the energy transition. The literature has identified technological, institutional, and behavioural carbon lock-ins. In our paper, we add to this the concept of discursive carbon lock-in. Based on a Foucaultian understanding of power, we argue that discourse is a crucial dimension of lock-in. This implies that we need to carefully investigate the dominant discourses that constitute and justify the very technologies, institutions and behaviours of the status quo. Looking back over the last 30 years, our literature review of discourse studies on the German energy transition reveals that both fossil fuels and more recently renewable energies have become discursively locked in. The role of coal and gas has been reiterated by the ‘energy mix’ discourse that highlighted the need for fossils as a bridging technology in the energy transition. We show that Germany is nowhere near to phasing out coal in the short term. We conclude that discursive carbon lock-in is an important (though by no means the only) factor that explains why coal remains an established part of the German energy mix.

Heating and cooling using aquifer thermal energy storage (ATES) has hardly been applied outside the Netherlands, even though it could make a valuable contribution to the energy transition. The Climate-KIC project "Europe-wide Use of Energy from aquifers" - E-USE(aq) - aimed to pave the way for Europe-wide application of ATES, through the realization and monitoring of six ATES pilot plants across five different EU countries. In a preceding paper, based on preliminary results of E-USE(aq), conclusions were already drawn, demonstrating how the barriers for this form of shallow geothermal energy can be overcome, and sometimes even leveraged as opportunities. Based on final pilot project results, key economic and environmental outcomes are now presented. This paper starts with the analysis of specific technological barriers: unfamiliarity with the subsurface, presumed limited compatibility with existing energy provision systems (especially district heating), energy imbalances and groundwater contamination. The paper then shows how these barriers have been tackled, using improved site investigation and monitoring technologies to map heterogeneous subsoils. In this way ATES can cost-efficiently be included in smart grids and combined with other sources of renewable (especially solar) energy, while at the same time achieving groundwater remediation. A comparative assessment of economic and environmental impacts of the pilots is included, to demonstrate the sustainability of ATES system with different renewables and renewable-based technologies. The paper concludes with an assessment of the market application potential of ATES, including in areas with water scarcity, and a review of climate beneficial impact.

In acknowledgement of the complexity of environmental challenges, research on learning in environmental policy has grown substantially over the past two decades across a range of disciplines. Despite this growth, there are few comprehensive assessments of the literature on learning in environmental policy. This article fills this gap by providing insights on the overall coherence and impact of this body of scholarship. To do so, we analyze a sample of 163 articles from 2004 to 2014 using a standardized coding framework. The results provide an in-depth assessment of the status of the literature on learning in the context of environmental policy, as well as the quality of the literature. We demonstrate that despite the diversity in research questions and goals, the literature is lacking with respect to diversity in cases and context, theoretical development, clear conceptualization and operationalization of learning, and advancements in empirical approaches to study learning. From these insights, we discuss the challenges and opportunities for scholars in studying learning and provide recommendations for building the theoretical and methodological rigor of the field.

This datafile is part of a study that shows how the implementation of a new and sustainable land use on rewetted peatlands with production of biomass (Sphagnum paludiculture) aids organic matter, carbon and nutrient accumulation. The measurements were conducted on a Sphagnum paludiculture site in Germany from March 2014 until June 2021. The site was installed in 2011 and expanded in 2016 (see methods below for more details). This file includes (see codebook below for details) data obtained with a field measurements on a Sphagnum paludiculture (Germany, datafile ‘Temmink et al. time series’ and ‘Temmink et al. biomass’). The datafiles contain data related to pore and surface water nutrient concentrations over time, organic matter accumulation and nutrient content of the organic matter after 5 or 10 years. Not all data presented in the data files were used in the manuscript, but are provided as additional information to interested researchers. Contact person: Ralph Temmink - r.j.m.temmink@uu.nl

Recycling. Als we in 2050 een volledig circulaire economie willen hebben, moeten we statiegeld invoeren voor kleine flesjes en blikjes, schrijven 23 hoogleraren.