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Goedbloed J.P.,Institute for Energy and Transport of the Netherlands
43rd European Physical Society Conference on Plasma Physics, EPS 2016 | Year: 2016

The development of MHD stability theory of laboratory and astrophysical plasmas with sizeable background flows, initiated long ago, has severely suffered from the wide spread misunderstanding that this theory necessarily involves non-self-adjoint operators. The new theory of the Spectral Web, on the contrary, is entirely constructed on the basis of the two quadratic forms of the potential energy and the averaged Doppler-Coriolis shift, both involving a self-adjoint operator. This approach finally provides order in the bewildering variety of complex eigenvalues that are obtained from high resolution spectral codes. This order obtains from a monotonicity property of the eigenvalues in the complex plane along the two sets of curves that constitute the spectral web. Such a property was long thought to be restricted to the real eigenfunctions of static equilibria, but it has now been generalized for the complex eigenfunctions of stationary equilibria. The monotonicity can not be based on node counting of the eigenfunctions, but it involves a quantity called the complementary energy which represents the energy needed to sustain the Doppler-Coriolis shifted oscillations of the instabilities. Thus, the full complex spectrum of stationary plasmas is obtained together with a connecting structure. This permits to consider the enormous diversity of MHD instabilities of laboratory and astrophysical plasmas with arbitrary flow and rotation profiles from a single unifying viewpoint. The method is illustrated with old and new instabilities of a force free field equilibrium subjected to shear flow.

Baldi A.,Stanford University | Baldi A.,Institute for Energy and Transport of the Netherlands | Narayan T.C.,Stanford University | Koh A.L.,Stanford University | And 2 more authors.
Nature Materials | Year: 2015

Many energy-and information-storage processes rely on phase changes of nanomaterials in reactive environments. Compared to their bulk counterparts, nanostructured materials seem to exhibit faster charging and discharging kinetics, extended life cycles, and size-tunable thermodynamics. However, in ensemble studies of these materials, it is often difficult to discriminate between intrinsic size-dependent properties and effects due to sample size and shape dispersity. Here, we detect the phase transitions of individual palladium nanocrystals during hydrogen absorption and desorption, using in situ electron energy-loss spectroscopy in an environmental transmission electron microscope. In contrast to ensemble measurements, we find that palladium nanocrystals undergo sharp transitions between the α and Î 2 phases, and that surface effects dictate the size dependence of the hydrogen absorption pressures. Our results provide a general framework for monitoring phase transitions in individual nanocrystals in a reactive environment and highlight the importance of single-particle approaches for the characterization of nanostructured materials. © 2015 Macmillan Publishers Limited.

Moya J.A.,Institute for Energy and Transport of the Netherlands | Pardo N.,Institute for Energy and Transport of the Netherlands | Mercier A.,Institute for Energy and Transport of the Netherlands
Journal of Cleaner Production | Year: 2011

This paper performs a cost-effectiveness analysis of some of the best available technologies (BAT) that can contribute to decreasing the energy consumption and CO2 emissions in the European Union's (EU27) cement industry. Several capital budgeting decision criteria have been used (the payback period, the net present value and the internal rate of return) to study whether or not an investment should be considered worthwhile. The results show that, independent of the capital budgeting decision criteria used, the number of cost-effective retrofitting possibilities available is large compared to the rate of improvements that the industry undertakes annually. This shows the insensitivity of the industry to financial criteria when it comes to making their investment decisions. The possible thermal energy improvement in the clinker production, if all these BATs were implemented, has been quantified to be around 10%. This achievement would place the cement industry in the upper bound of the benchmark range for clinker manufacture. However considering the delays observed nowadays in terms of diffusion of BATs in the cement industry, it requires a conducive policy environment that combines support for both technology development and to their deployment. © 2011 Elsevier Ltd. All rights reserved.

Gracceva F.,Institute for Energy and Transport of the Netherlands | Zeniewski P.,Institute for Energy and Transport of the Netherlands
Energy | Year: 2013

This paper aims to quantitatively explore the uncertainty around the global potential of shale gas development and its possible impacts, using a multi-regional energy system model, TIAM (TIMES Integrated Assessment Model). Starting from the premise that shale gas resource size and production cost are two key preconditions for its development, our scenario analysis reveals the way these and other variables interact with the global energy system, impacting on the regional distribution of gas production, interregional gas trade, demand and prices. The analysis shows how the reciprocal effects of substitutions on both the supply and demand-side play an important role in constraining or enabling the penetration of shale gas into the energy mix. Moreover, we systematically demonstrate that the global potential for shale gas development is contingent on a large number of intervening variables that manifest themselves in different ways across regionally-distinct energy systems. A simple theoretical model is derived from the results of the scenario analysis.Its purpose is to simplify and explain the complex behaviour of the system, by illustrating the chain of actions and feedbacks induced by different shale gas economics, their magnitude, their relative importance, and the necessary conditions for the global potential to be realised. © 2013 Elsevier Ltd.

Goedbloed J.P.,Institute for Energy and Transport of the Netherlands
Physics of Plasmas | Year: 2012

It is shown that some of the main results of the recent paper by Lakhin and Ilgisonis [Phys. Plasmas 18, 092103 (2011)], viz. the derivation of the equations for the continuous spectra of poloidally and toroidally rotating plasmas and their special solution for large aspect ratio tokamaks with large parallel flows were obtained before by Goedbloed, Beliën, van der Holst, and Keppens [Phys. Plasmas 11, 28 (2004)]. A further rearrangement of the system of equations for the coupled Alfvén and slow continuous spectra clearly exhibits: (a) coupling through a single tangential derivative, which is a generalization of the geodesic curvature; (b) the transonic transitions of the equilibrium, which need to be carefully examined in order to avoid entering hyperbolic flow regimes where the stability formalism breaks down. A critical discussion is devoted to the implications of this failure, which is generally missed in the tokamak literature, possibly as a result of the wide-spread use of the sonic Mach number of gas dynamics, which is an irrelevant and misleading parameter in transonic magnetohydrodynamics. Once this obstacle in understanding is removed, further application of the theory of trans-slow Alfvén continuum instabilities to both tokamaks, with possible implications for the L-H transition, and astrophysical objects like fat accretion disks, with a possible new route to magnetohydrodynamic turbulence, becomes feasible. © 2012 American Institute of Physics.

Barlas T.K.,Institute for Energy and Transport of the Netherlands | van Kuik G.A.M.,Institute for Energy and Transport of the Netherlands
Progress in Aerospace Sciences | Year: 2010

This article presents a review of the state of the art and present status of active aeroelastic rotor control research for wind turbines. Using advanced control concepts to reduce loads on the rotor can offer great reduction to the total cost of wind turbines. With the increasing size of wind turbine blades, the need for more sophisticated load control techniques has induced the interest for locally distributed aerodynamic control systems with build-in intelligence on the blades. Such concepts are often named in popular terms 'smart structures' or 'smart rotor control'. The review covers the full span of the subject, starting from the need for more advanced control systems emerging from the operating conditions of modern wind turbines and current load reduction control capabilities. An overview of available knowledge and up-to date progress in application of active aerodynamic control is provided, starting from concepts, methods and achieved results in aerospace and helicopter research. Moreover, a thorough analysis on different concepts for smart rotor control applications for wind turbines is performed, evaluating available options for aerodynamic control surfaces, actuators (including smart materials), sensors and control techniques. Next, feasibility studies for wind turbine applications, preliminary performance evaluation and novel computational and experimental research approaches are reviewed. The potential of load reduction using smart rotor control concepts is shown and key issues are discussed. Finally, existing knowledge and future requirements on modeling issues of smart wind turbine rotors are discussed. This study provides an overview of smart rotor control for wind turbines, discusses feasibility of future implementation, quantifies key parameters and shows the challenges associated with such an approach. © 2009 Elsevier Ltd. All rights reserved.

Moya J.A.,Institute for Energy and Transport of the Netherlands | Pardo N.,Institute for Energy and Transport of the Netherlands
Journal of Cleaner Production | Year: 2013

This paper analyses the cost effectiveness of the implementation of some of the Best Available Technologies (BATs) and Innovative Technologies (ITs) in the European industry up to 2030. This is done using a bottom-up model that considers the main processes involved in each facility. The model described in the paper assumes the retrofitting/upgrade of each European facility with a BAT or IT as soon as the criterion for a capital budgeting decision is met. The paper details the effect on the savings in energy and CO2 emissions by European industry, assuming different levels of requirement in the payback period used as main capital-budgeting decision criterion. This approach reveals the full potential that some technologies under research (as the ones considered in the Ultra-Low CO2 Steelmaking project and Carbon Capture and Storage technologies, as well as other technologies that are not widely deployed (Direct Reduced Iron technologies), may have in the European industry. The starting point of the simulation is adjusted so that the CO2 emissions of each facility in the model have a counterpart in the emissions recorded for the benchmarking exercise of the European Union Emissions Trading Scheme. The results show that, by 2030, for a payback period of two years, the margin of improvement in CO2 emissions is around 20%. Whereas, by 2030, for a payback period of six years, the margin of improvement in CO 2 emissions is in the range between 50% and 65%. © 2013 Elsevier Ltd. All rights reserved.

Corsatea T.D.,Institute for Energy and Transport of the Netherlands
Renewable and Sustainable Energy Reviews | Year: 2014

This paper contributes to the development of renewable energy innovation metrics through an exploration of innovation patterns across the European countries in 2010. The identified localized innovation capabilities describe the health of the wind, solar and bioenergy sectors, highlighting a concentrated RES innovation activity within four countries: Germany, France, United Kingdom and Denmark. The association of technological capabilities along the innovation composite indicators allows the extraction of useful insights of the role of environmental policies on employment and technological change. Briefly, the corporate research investment per patent is lower for wind energy (EUR 0.61 million) and higher for PV and biofuels (approximately EUR 1 million). Important lever of innovation capabilities across Europe is identified within public support to deployment, which provides significant insights in terms of economic efficiency of generation technologies; the investigation finds job ratios which are higher for wind and lower for PV technology. As the evolution of the market drives the patterns of innovation activities for all selected technologies, considerable financial consequences are identified in the context of delocalization of clean technology manufacturers. © 2014 Elsevier Ltd.

Gracceva F.,Institute for Energy and Transport of the Netherlands | Zeniewski P.,Institute for Energy and Transport of the Netherlands
Applied Energy | Year: 2014

Until now, the complex relationship between energy security and climate change has been addressed using a partial understanding of security, one that is based on simplified indicators such as import dependence or fuel mix diversity. As a consequence, the synergies and trade-offs between climate change and energy security policies have not been systematically explored according to a wider understanding of the latter concept. The purpose of this article is to resolve the resulting knowledge gap by proposing a theoretical approach to energy security that is consistent with its multi-dimensional nature, taking into account the whole energy supply chain. Five key 'systemic' properties of energy security will be identified - namely, stability, flexibility, adequacy, resilience and robustness. The paper proposes a novel framework to assess energy security and uses this framework to develop a comprehensive approach to the interactions between climate change policies and energy security. The impact of a low-carbon scenario on one of these five properties (long-term robustness) will be assessed using a complex multi-regional energy system model. The results demonstrate how this scenario induces structural changes along the whole energy supply chain, revealing dynamic vulnerabilities and trade-offs that are not adequately accounted for by existing indicator-based assessments. Finally, the paper provides solid foundations for further analysis of these trade-offs using more detailed sectoral models. © 2013 Elsevier Ltd.

Sorensen J.N.,Technical University of Denmark | Van Kuik G.A.M.,Institute for Energy and Transport of the Netherlands
Wind Energy | Year: 2011

General momentum theory is used to study the behaviour of the 'classical' free vortex wake model of Joukowsky. This model has recently attained considerable attention as it shows the possibility of achieving a power performance that greatly exceeds the Lanchester-Betz limit for rotors running at low tip speed ratios. This behaviour is confirmed even when including the effect of a centre vortex, allowing azimuthal velocities and the associated radial pressure gradient to be taken into account in the axial momentum balance without any simplifying assumptions. It is shown that the most likely explanation for the anomalous behaviour at small tip speed ratios is that the influence of the lateral component of pressure and friction is neglected in the axial momentum theorem. A refined model is proposed that remedies the problem of using the axial momentum theorem and by which the power coefficient never exceeds the Lanchester-Betz limit and which tends to zero at zero tip speed ratio. © 2010 John Wiley & Sons, Ltd.

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