Renewable Energy

Utility-scale wind turbines operate in dynamic flows that can vary significantly over timescales from less than a second to several years. To better understand the inflow to utility-scale turbines, two inflow towers were installed and commissioned at the National Renewable Energy Laboratory's (NREL) National Wind Technology Center near Boulder, Colorado, in 2011. These towers are 135 m tall and instrumented with a combination of sonic anemometers, cup anemometers, wind vanes, and temperature measurements to characterize the inflow wind speed and direction, turbulence, stability and thermal stratification to two utility-scale turbines. Herein, we present variations in mean and turbulent wind parameters with height, atmospheric stability, and as a function of wind direction that could be important for turbine operation as well as persistence of turbine wakes. Wind speed, turbulence intensity, and dissipation are all factors that affect turbine performance. Our results show that these all vary with height across the rotor disk, demonstrating the importance of measuring atmospheric conditions that influence wind turbine performance at multiple heights in the rotor disk, rather than relying on extrapolation from lower levels.

... Font Size: Decrease Font Size Increase Font Size. ... This study aims to fill the gap in the literature on time series of flow overtopping low crested structures. ... This wave energy converter extracts energy from the waves, by funnelling them to run-up a ramp and overtop into a reservoir ...

Quantization of the magneto-thermoelectric transport is studied when an external d.c. magnetic field is applied to the C/N-knot formed as crossing between a narrow stripe of conducting atomic monolayer C on the one hand, and a metal stripe N on the other hand. The temperature gradient in C is created by injecting the non-equilibrium electrons, holes and phonons from the heater H thereby directing them toward the C/N-knot. A non-linear coupling between electron states of the C/N-knot counter-electrodes causes splitting of the heat flow into several fractions owing to the Lorentz force acting in the C/N-knot vicinity, thereby inducing the magneto-thermoelectric
current in N, whereas the phonons pass and propagate along C further ahead. The heat flow along C generates a transversal electric current in N showing a series of maxima when dimensions of the Landau orbits and the C/N-knot match each other. It allows observing the interplay between the quantum Hall effect and the spatial quantization.

conversion of thermal energy into electricity is considered in the electrically polarized graphene
stripes with zigzag edges where the heavy chiral fermion (HCF) states are formed. The stripes are characterized
by a high electric conductance Ge and by a significant Seebeck coefficient S. The electric current
in the stripes is induced due to a non-equilibrium thermal injection of “hot” electrons. This thermoelectric
generation process might be utilized for building of thermoelectric generators with an exceptionally high
figure of merit ZδT  1 and with an appreciable electric power densities ∼1 MW/cm2.

Materials science will play a key role in the further development of emerging solutions for the increasing problems of energy and environment. Materials found in nature have many inspiring structures, such as hierarchical organizations, periodic architectures, or nanostructures, that endow them with amazing functions, such as energy harvesting and conversion, antireflection, structural coloration, superhydrophobicity, and biological self-assembly. Biotemplating is an effective strategy to obtain morphology-controllable materials with structural specificity, complexity, and related unique functions. Herein, we highlight the synthesis and application of biotemplated materials for six key areas of energy and environment technologies, namely, photocatalytic hydrogen evolution, CO(2) reduction, solar cells, lithium-ion batteries, photocatalytic degradation, and gas/vapor sensing. Although the applications differ from each other, a common fundamental challenge is to realize optimum structures for improved performances. We highlight the role of four typical structures derived from biological systems exploited to optimize properties: hierarchical (porous) structures, periodic (porous) structures, hollow structures, and nanostructures. We also provide examples of using biogenic elements (e.g., C, Si, N, I, P, S) for the creation of active materials. Finally, we disscuss the challenges of achieving the desired performance for large-scale commercial applications and provide some useful prototypes from nature for the biomimetic design of new materials or systems. The emphasis is mainly focused on the structural effects and compositional utilization of biotemplated materials.

No âmbito dos debates internacionais sobre mudanças climáticas, a China tradicionalmente se posiciona ao lado dos países em desenvolvimento, defendendo o seu direito de se industrializar e crescer economicamente. Em alinhamento com o princípio das responsabilidades comuns, porém diferenciadas, a China argumenta que o dever de reduzir as emissões de Gases do Efeito Estufa  (GHGs) recai principalmente sobre os países desenvolvidos, visto a trajetória histórica de poluição atmosférica e o elevado nível de emissões per capita destes países. No entanto, nota-se uma mudança no posicionamento chinês no decorrer dos últimos anos, sinalizando uma maior disposição em limitar as suas emissões de CO2 e promover uma transição para um novo patamar econômico e produtivo mais alinhado aos princípios da sustentabilidade.

Abstract - Extraction of cryptographic keys, passwords
and other sensitive information from the memory, has been
made possible by the data remanence property of DRAM.
According to it, DRAM can retain its data for several
seconds to minutes without power [I]. Cold boot attack
proposed in [I] tries to exploit memory remanence property,
for extracting probable cryptographic secrets from DRAM.
However, extracted information is degraded and needs to be
corrected before being used for decrypting the encrypted
files. Various methods for correcting this distorted data for
different cryptosystems have been proposed [1, 6]. However,
it has not been reported much in literature regarding
efficacy of these methods. This paper contains results and
observations of extensive experiments carried out for
correcting AES keys, by varying timings of cold rebooting
the PC that varies the % of distorted data. These
observations suggest that the proposed methods are
theoretical in nature and not effective practically( for cold
boot attack) as they could correct keys corresponding to up
to 2% of erroneous round key schedules of AES-128 and
AES-256. In this paper, an improved algorithm has been
proposed for correcting up to 15% of errors in cold boot
attack generated as well as randomly generated distorted
round key schedules. The proposed algorithm has been
successfully implemented to mount the volumes encrypted
by popular disk encryption system 'TrueCrypt'.

Policymakers should recognise the size and value of the woodfuel sector and its importance to many people. Harvesters and producers need better access to trees and land to promote better management and reduce conflicts. The tax system for woodfuel should be revised to be transparent and pragmatic. Woodfuel from plantation forests and agroforestry should be favoured over woodfuel from valuable or threatened tree species. More attention should be paid to energy-efficient charcoal kilns and cooking stoves, as well as activities to promote ...

ABSTRACT The management of wood energy has become a major concern for the international community and is the focus of debates in Central Africa. The Makala Project, funded by the EU, fits within this context with the objective of securing the supply of wood energy to urban centers. Over the past three years, various forest resources management techniques have been designed and an assessment of the wood energy sector has been conducted in Kinshasa. Various technical itineraries have been proposed for the management of areas dedicated to the supply of wood energy at various levels, from the farming plot to the village land, and from the individual approach to the collective approach. This article provides a snapshot of the activities developed by the Makala Project to improve the management of periurban forest ecosystems and to secure the supply in wood energy.

This paper addresses the question, how can sustainable energy projects increase engagement from consumers using interactive media communications? To this end, a systematic literature review was conducted in order to synthesise findings across four major disciplines, with the goal of identifying current and imminent challenges, as well as potential solutions, to engaging consumers with sustainable energy projects in the era of interactive media. The authors propose a Socially Dynamic Communications Framework (SDCF) that can be used organisationally to address core challenges and generate solutions within a single iterative cycle. Initial findings indicate that consumer behaviours are most likely to be influenced through strategic social interactions using diverse, networked platforms, in order to be meaningful in contemporary social and technological contexts. Furthermore, this type of interaction is likely to become integral to future energy delivery systems, making interactive, online engagement with energy initiatives an important area for investigation. While many organisations may cite a lack of control in digital and social media as a risk justifying avoidance, the majority of engagement and marketing literature emphasise the greater risk inherent in not engaging effectively online.

This paper present the results of investigation carried out in studying the fuel properties of cashew nut shell and its gasification feasibility for open core down draft gasifier. Cashew nut shell was converted to producer gas in an open core down draft gasifier whose performance was evaluated in terms of fuel consumption rate, calorific value of producer gas and gasification efficiency at different gas flow rates. It was found that producer gas calorific value and volumetric percentage of its combustible constituents, along with gasification ...