NREL has recently begun investing polymer-based photovoltaic cells. We present initial results on a novel energy conversion device that uses both semiconducting polymers and organic small molecules as photoactive layers, using the advantageous properties of both classes of materials. By incorporating polymers into the device, we see results that are surprisingly good for a planar organic device...

0277-5387/$ see front matter 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.poly.2013.12.003 ⇑ Corresponding author at: Department of Chemistry, Yale University, P.O. Box 208107, New Haven, CT 06520-8107, USA. E-mail address: [email protected] (R.H. Crabtree). 1 Current address: NREL–National Bioenergy Center15013 Denver W. Parkway MS 3313, Golden, CO 80401, USA Oana...

The wake produced by a utility-scale wind turbine invested laminar, uniform inflow is analyzed means of two different modal decompositions, the proper orthogonal decomposition (POD) and dynamic mode (DMD), in its sparsity-promoting variant. considered NREL-5MW at tip-speed ratio λ=7 diameter-based Reynolds number order 108. flow simulated through large eddy simulation, where forces exerted blad...

As interest in lignocellulosic biomass feedstocks for conversion into transportation fuels grows, the summative compositional analysis of biomass, or plant-derived material, becomes ever more important. The sulfuric acid hydrolysis of biomass has been used to measure lignin and structural carbohydrate content for more than 100 years. Researchers have applied these methods to measure the lignin ...

ZnCl2 hydrate, the main molten salt used in biomass conversion, combined with low concentration HCl is an excellent solvent for the dissolution and hydrolysis of the carbohydrates present in lignocellulosic biomass. The most recalcitrant carbohydrate, cellulose, is dissolved in a residence time less than 1 h under mild conditions without significant degradation. This technology is referred to a...

This study aims to develop a mathematical model to evaluate the energy required by pretreatment processes used in the production of second generation ethanol. A dilute acid pretreatment process reported by National Renewable Energy Laboratory (NREL) was selected as an example for the model's development. The energy demand of the pretreatment process was evaluated by considering the change of in...

This paper presents the parameterization and optimization of two well-known airfoils. The aerodynamic shape investigation includes subsonic (NREL S-821) transonic airfoils (RAE-2822). class transformation is employed for parametrization while genetic algorithm used purposes. absolute scheme process carried out minimization drag coefficient maximization lift to ratio. In-house MATLAB code incorp...

This paper deals with the power generation control in variable speed wind turbines. In this context, a control strategy is proposed to ensure power extraction optimization of a DFIGbased wind turbine. The proposed control strategy combines an MPPT using a high gain observer and second-order sliding mode for the DFIG control. This strategy presents attractive features such as chattering-free beh...

This publication received minimal editorial review at NREL. NOTICE This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of ...

wind power has been widely considered in recent years as an available and a clean renewable energy source. the cost of wind energy production is currently the main issue, and increasing the size of wind turbines can reduce wind energy production costs. hence, megawatt wind turbines are being rapidly developed in recent years. in this paper, an aerodynamic analysis of the nrel 5mw turbine is car...