188 research outputs found
Harnessing Flexible and Reliable Demand Response Under Customer Uncertainties
Demand response (DR) is a cost-effective and environmentally friendly
approach for mitigating the uncertainties in renewable energy integration by
taking advantage of the flexibility of customers' demands. However, existing DR
programs suffer from either low participation due to strict commitment
requirements or not being reliable in voluntary programs. In addition, the
capacity planning for energy storage/reserves is traditionally done separately
from the demand response program design, which incurs inefficiencies. Moreover,
customers often face high uncertainties in their costs in providing demand
response, which is not well studied in literature.
This paper first models the problem of joint capacity planning and demand
response program design by a stochastic optimization problem, which
incorporates the uncertainties from renewable energy generation, customer power
demands, as well as the customers' costs in providing DR. We propose online DR
control policies based on the optimal structures of the offline solution. A
distributed algorithm is then developed for implementing the control policies
without efficiency loss. We further offer enhanced policy design by allowing
flexibilities into the commitment level. We perform real world trace based
numerical simulations. Results demonstrate that the proposed algorithms can
achieve near optimal social costs, and significant social cost savings compared
to baseline methods
Incentivizing Reliable Demand Response with Customers' Uncertainties and Capacity Planning
One of the major issues with the integration of renewable energy sources into
the power grid is the increased uncertainty and variability that they bring. If
this uncertainty is not sufficiently addressed, it will limit the further
penetration of renewables into the grid and even result in blackouts. Compared
to energy storage, Demand Response (DR) has advantages to provide reserves to
the load serving entities (LSEs) in a cost-effective and environmentally
friendly way. DR programs work by changing customers' loads when the power grid
experiences a contingency such as a mismatch between supply and demand.
Uncertainties from both the customer-side and LSE-side make designing
algorithms for DR a major challenge.
This paper makes the following main contributions: (i) We propose DR control
policies based on the optimal structures of the offline solution. (ii) A
distributed algorithm is developed for implementing the control policies
without efficiency loss. (iii) We further offer an enhanced policy design by
allowing flexibilities into the commitment level. (iv) We perform real world
trace based numerical simulations which demonstrate that the proposed
algorithms can achieve near optimal social cost. Details can be found in our
extended version.Comment: arXiv admin note: substantial text overlap with arXiv:1704.0453
Organic Field-Effect Transistor: Device Physics, Materials, and Process
Organic field-effect transistors have received much attention in the area of low cost, large area, flexible, and printable electronic devices. Lots of efforts have been devoted to achieve comparable device performance with high charge carrier mobility and good air stability. Meanwhile, in order to reduce the fabrication costs, simple fabrication conditions such as the printing techniques have been frequently used. Apart from device optimization, developing novel organic semiconductor materials and using thin-film alignment techniques are other ways to achieve high-performance devices and functional device applications. It is expected that by combining proper organic semiconductor materials and appropriate fabrication techniques, high-performance devices for various applications could be obtained. In this chapter, the organic field-effect transistor in terms of device physics, organic materials, device process, and various thin-film alignment techniques will be discussed
Effects of Optical Interference and Annealing on the Performance of Polymer/Fullerene Bulk Heterojunction Solar Cells
Applications of Chemical Kinetics in Heterogeneous Catalysis
Chemical kinetics is a key subdiscipline of physical chemistry that studies the reaction rate in every elemental step and corresponding catalytic mechanism. It mainly concludes molecular reaction dynamics, catalytic dynamics, elemental reaction dynamics, macrodynamics, and microdynamics. Such a research field has wide applications in heterogeneous catalysis. Based on the Arrhenius plot fitted by the catalytic conversions below 15% without the mass transfer effect and heat transfer effect, the apparent activation energy echoing with the intrinsically catalytic sites and the pre-exponential factor echoing with the relative number of active sites can be, respectively, derived from the slope and intercept of the Arrhenius plots, which can be used to compare the intrinsically catalytic activity of different catalysts and the relative amount of active sites. Reaction orders of both reactants and products are derived from the reaction rate equation and also fitted by the catalytic conversions below 15% without the mass transfer effect and heat transfer effect. According to the acquired reaction orders, the reaction mechanism can be proposed and even defined in some simple reactions. Therefore, investigations of chemical kinetics are of extreme importance and meaning in heterogeneous catalysis
Efficient Inverted ITO-Free Organic Solar Cells Based on Transparent Silver Electrode with Aqueous Solution-Processed ZnO Interlayer
Efficient inverted organic solar cells (OSCs) with the MoO3 (2 nm)/Ag (12 nm) transparent cathode and an aqueous solution ZnO electron extraction layer processed at low temperature are investigated in this work. The blend of low bandgap poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl]] (PTB7) and [6,6]-phenyl-C71-butyric acid methylester (PC71BM) is employed as the photoactive layer here. A power conversion efficiency (PCE) of 5.55% is achieved for such indium tin oxide- (ITO-) free OSCs under AM 1.5G simulated illumination, comparable to that of ITO-based reference OSCs (PCE of 6.11%). It is found that this ZnO interlayer not only slightly enhances the transparency of MoO3/Ag cathode but also obtains a lower root-mean-square (RMS) roughness on the MoO3/Ag surface. Meanwhile, ITO-free OSCs also show a good stability. The PCE of the devices still remains above 85% of the original values after 30 days, which is slightly superior to ITO-based reference OSCs where the 16% degradation in PCE is observed after 30 days. It may be instructive for further research of OSCs based on metal thin film electrodes
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