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The optical and photovoltaic properties of Si NCs / SiC multilayers (MLs) are investigated using a membrane-based solar cell structure. By removing the Si substrate in the active cell area, the MLs are studied without any bulk Si substrate contribution. The occurrence is confirmed by scanning electron microscopy and light-beam induced current mapping . Optical characterization combined with simulations allows us to determine the absorption within the ML absorber layer, isolated from the other cell stack layers. The results indicate that the absorption at wavelengths longer than 800 nm is only due to the SiC matrix. The measured short-circuit current is significantly lower than that theoretically obtained from absorption within the ML absorber, which is ascribed to losses that limit carrier extraction. The origin of these losses is discussed in terms of the material regions where recombination takes place. Our results indicate that carrier extraction is most efficient from the Si NCs themselves, whereas recombination is strongest in SiC and residual a-Si domains . Together with the observed onset of the external quantum efficiency (EQE) at 700-800 nm, this fact is an evidence of quantum confinement in Si NCs embedded in SiC on device level.

We try to understand the role of technological change and diffusion of energy efficient technologies in order to explain the trend of energy intensity developments in the German steel industry. We selected six key energy efficient technologies and collected data to derive their diffusion since their introduction in Germany. Since all technologies have been applied in Germany for more than 30 years we would expect complete diffusion. We found complete diffusion only for basic oxygen furnaces and continuous casting. Newer technologies (i.e. basic oxygen furnace gas recovery, top pressure recovery turbine, coke dry quenching and pulverized coal injection) diffused quicker in the initial phase but then diffusion slowed down. Key improvements in energy efficiency are due to electric arc furnaces (24%), basic oxygen furnaces (12%), and continuous casting (6%) between 1958 and 2012. The contribution of top pressure recovery turbines, pulverized coal injection and basic oxygen furnaces gas recovery accounts in total of about 3%. If the selected technologies were diffused completely, the future energy consumption could be reduced by 4.5% compared to 2012. Our findings suggest that our selection of six technologies is the key driver for energy intensity developments within the German steel industry between 1958 and 2012.

As Europe is not on track in meeting its 2020 energy savings target, there has been quite some debate to make the energy savings target binding instead of indicative. Although the final draft text of the Energy Efficiency Directive left the option of a binding target explicitly open for the period beyond 2014, this statement has watered down in the adopted Directive: If still not on track mid-2014, the European Commission will propose "further measures." In this paper, we argue that a binding energy savings target could be the first EU legal initiative to look beyond 2020 serving as a beacon for other policies such as for renewables and greenhouse gases that need redefinition after 2020. We therefore explore four possible design options of a binding savings target and assess their feasibility. We conclude that a binding target at Member State level (opposed to an EU-wide target like for the EU Emission Trading System (ETS)) is the most feasible. A binding target at Member State level would ensure political accountability and commitment to deliver results while providing flexibility to choose and apply the most suitable tools to achieve the target. It could provide a framework to guide ambitious and coherent implementation of EU energy efficiency policies, as well as the strengthening of national policies. Furthermore, binding targets at Member State level will make Member States take an ambitious position in Brussels when new energy or CO2 performance standards for appliances and transport modes are to be set. A Member State binding target applied to end-users (excluding ETS companies) is a design option that covers the vast majority of the cost-effective energy savings potential, maintains the flexibility for ETS companies, and supports the most cost-effective achievement of a greater share of renewables.

The goal of this paper is to review bottom-up models for industrial energy demand with a particular focus on their capability to model barriers to the adoption of energy-efficient technologies. The integration of barriers into the models is an important prerequisite for a more detailed and realistic modeling of policies for energy efficiency. Particularly with the emergence of more and more varying policy instruments, it also becomes crucial for the models to take account of these policies as well as the barriers they address in a more realistic way. Our review revealed that, despite the broadly evident existence of market failures and barriers for energy-efficient technologies, they are only partly and in a rather aggregated form considered in today's bottom-up models. The state-of-the-art bottom-up model is based on an explicit representation of the technology stock and considers the costs of energy efficiency options in detail. But with regard to barriers, most models only make use of an aggregated approach, like an adjusted discount rate. While some models do not even consider technology costs and energy prices, but instead use exogenous technology diffusion rates, other more advanced models took first steps towards considering barriers in more detail. The latter allows differentiation between multiple parameters that influence technology adoption. Still, even in the most advanced models, only a few of the observed barriers are explicitly considered. At the same time, new approaches to considering barriers like uncertainty or the (slow) spread of information are being developed in other disciplines. We conclude the paper by summarizing promising ways to improve representation of barriers in bottom-up models.

Abstract For a successful transition from internal combustion engines to electric vehicles and from conventional power plants to renewable energy supply, battery technology plays a vital role. Accordingly, battery research and development (R&D) efforts have been increased considerably over the past decades, particularly regarding materials and cell chemistries to further improve the electrochemical performance of lithium ion batteries. The impetus behind such massive R&D has been the replacement of metallic lithium anodes, a notorious for potentially catastrophic shorting by lithium metal dendrites. However, despite the promise of a step improvement in energy density outperforming established LIB technology, the commercial introduction of cells with alternative anode materials in the mass market is slow. Against this backdrop, the aim of the present study is to provide an overview of current developments in the academic and industrial research arena, summarising the historical development of scientific literature and patent landscape beyond established anode materials. The study identifies and critically reviews tin, silicon, silicon oxide, aluminium and titanium-based anode materials as promising pathways to develop high-energy density next-generation LIBs.

Lithium-ion batteries are currently the most advanced electrochemical energy storage technology due to a favourable balance of performance and cost properties. Driven by forecasted growth of the electric vehicles market, the cell production capacity for this technology is continuously being scaled up. However, the demand for better performance, particularly higher energy densities and/or lower costs, has triggered research into post-lithium-ion technologies such as solid-state lithium metal, lithium–sulfur and lithium–air batteries as well as post-lithium technologies such as sodium-ion batteries. Currently, these technologies are being intensively studied with regard to material chemistry and cell design. In this Review, we expand on the current knowledge in this field. Starting with a market outlook and an analysis of technological differences, we discuss the manufacturing processes of these technologies. For each technology, we describe anode production, cathode production, cell assembly and conditioning. We then evaluate the manufacturing compatibility of each technology with the lithium-ion production infrastructure and discuss the implications for processing costs. Tremendous research progress has been made in the development of post-lithium-ion batteries (PLIBs), yet there is little discussion on the manufacturing of these upcoming technologies. In this Review, the authors survey the current production status of several representative PLIBs and offer an industrial-scale manufacturing outlook.

In 2008, a program was established in Germany to provide grants for energy audits in small- and medium-sized enterprises. It aims to overcome barriers to energy efficiency, like the lack of information or a lack of capacity, and is intended to increase the adoption of energy efficiency measures. We evaluate the program's impact in terms of energy savings, CO 2 mitigation, and cost-effectiveness. We find that firms adopt 1.7-2.9 energy efficiency measures, which they would not have adopted without the program. Taking a firm's perspective, the program shows a net present value ranging from -0.4 to 6 €/MWh saved, which very likely implies a net benefit. For the government, each ton of CO 2 mitigated costs between 1.8 and 4.1 €. Each euro of public expenditure on audit grants led to 17-33 € of private investment. The cost-effectiveness of the program for firms and the low share of public expenditure underline its value for the German energy efficiency policy mix and suggest that it should be expanded in Germany. Further, the good experiences with the program in Germany should encourage countries which have not yet established an audit program to do so.

AbstractHot‐wire chemical vapor deposition was utilized to develop rapidly grown and high‐quality phosphorus‐doped amorphous silicon (a‐Si:H) thin films for poly‐crystalline silicon on tunnel oxide carrier‐selective passivating contacts. Deposition rates higher than 150 nm/min were obtained for the in situ phosphorus‐doped a‐Si:H layers. To optimize the passivating contact performance, material properties such as microstructures as well as hydrogen content were characterized and analyzed for these phosphorus‐doped a‐Si:H films. The results show that a certain microstructure of the films is crucial for the passivation quality and the conductance of passivating contacts. Porous silicon layers were severely oxidized during high‐temperature crystallization, giving rise to very low conductance. The insufficient effective doping concentration in these layers also yields inferior passivation quality due to lack of field‐effect passivation. On the other hand, dense silicon layers are insensitive to oxidation but very sensitive to blistering of the films during the subsequent high‐temperature process steps. By optimizing the deposition parameters, a firing‐stable‐implied open‐circuit voltage of 737 mV and a contact resistivity of 10 mΩ·cm2were achieved at a high deposition rate of 100 nm/min while 733 mV and 90 mΩ·cm2were achieved at an even higher deposition rate of 150 nm/min.