Dynamics of photoconversion processes: the energetic cost of lifetime gain in photosynthetic and photovoltaic systems

2021 ◽  
Author(s):  
Robert Godin ◽  
James R. Durrant
Keyword(s):  
Kinetic Model ◽  
Solar Energy ◽  
Energy Conversion ◽  
Energy Cost ◽  
Energetic Cost ◽  
Photovoltaic Systems ◽  
Simple Kinetic Model ◽  
Energy Conversion Systems ◽  
Order Of Magnitude ◽  
The Cost

The energy cost of lifetime gain in solar energy conversion systems is determined from a breadth of technologies. The cost of 87 meV per order of magnitude lifetime improvement is strikingly close to the 59 meV determined from a simple kinetic model.

Speed, stride frequency and energy cost per stride: how do they change with body size and gait?

1988 ◽  
Vol 138 (1) ◽  
pp. 301-318 ◽  
Author(s):  
N. C. Heglund ◽  
C. R. Taylor
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Energy Cost ◽  
Reaction Force ◽  
Stride Frequency ◽  
Energetic Cost ◽  
Published Data ◽  
Frequency Change ◽  
Cost Of Locomotion ◽  
The Cost

In this study we investigate how speed and stride frequency change with body size. We use this information to define ‘equivalent speeds’ for animals of different size and to explore the factors underlying the six-fold difference in mass-specific energy cost of locomotion between mouse- and horse-sized animals at these speeds. Speeds and stride frequencies within a trot and a gallop were measured on a treadmill in 16 species of wild and domestic quadrupeds, ranging in body size from 30 g mice to 200 kg horses. We found that the minimum, preferred and maximum sustained speeds within a trot and a gallop all change in the same rather dramatic manner with body size, differing by nine-fold between mice and horses (i.e. all three speeds scale with about the 0.2 power of body mass). Although the absolute speeds differ greatly, the maximum sustainable speed was about 2.6-fold greater than the minimum within a trot, and 2.1-fold greater within a gallop. The frequencies used to sustain the equivalent speeds (with the exception of the minimum trotting speed) scale with about the same factor, the −0.15 power of body mass. Combining this speed and frequency data with previously published data on the energetic cost of locomotion, we find that the mass-specific energetic cost of locomotion is almost directly proportional to the stride frequency used to sustain a constant speed at all the equivalent speeds within a trot and a gallop, except for the minimum trotting speed (where it changes by a factor of two over the size range of animals studied). Thus the energy cost per kilogram per stride at five of the six equivalent speeds is about the same for all animals, independent of body size, but increases with speed: 5.0 J kg-1 stride-1 at the preferred trotting speed; 5.3 J kg-1 stride-1 at the trot-gallop transition speed; 7.5 J kg-1 stride-1 at the preferred galloping speed; and 9.4 J kg-1 stride-1 at the maximum sustained galloping speed. The cost of locomotion is determined primarily by the cost of activating muscles and of generating a unit of force for a unit of time. Our data show that both these costs increase directly with the stride frequency used at equivalent speeds by different-sized animals. The increase in cost per stride with muscles (necessitating higher muscle forces for the same ground reaction force) as stride length increases both in the trot and in the gallop.

Thin-Film Multilayer Filter Designs For Hybrid Solar Energy Conversion Systems

1985 ◽  
Author(s):  
L. DeSandre ◽  
D. Y. Song ◽  
H. A. Macleod ◽  
M. R. Jacobson ◽  
D. E. Osborn
Keyword(s):  
Thin Film ◽  
Solar Energy ◽  
Energy Conversion ◽  
Solar Energy Conversion ◽  
Energy Conversion Systems

Improved Heat Transfer Using Micro-Structures in Trifold Solar Energy Conversion Systems

2014 ◽  
Vol 659 ◽  
pp. 417-420
Author(s):  
Aristotel Popescu ◽  
David Pfund ◽  
Abel Hernandez-Guerrero ◽  
Ema Carmen Panaite ◽  
Ana Georgiana Lupu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Solar Energy ◽  
Energy Conversion ◽  
Renewable Energy Sources ◽  
Solar Energy Conversion ◽  
Thermal Systems ◽  
Heat Transfer Augmentation ◽  
Flow And Heat Transfer ◽  
Energy Conversion Systems ◽  
Micro Structures

The worldwide renewable energy sources harvesting grew recently at rates of 10–60% annually for many technologies, due to improvements made in all areas. In solar energy conversion, an improvement recently presented in literature is the hybrid system that provides both electricity and thermal energy for domestic applications. For the trifold PV-TE-DHW system, the electrical conversion efficiency is increased by using a thermoelectric (TE) module. This paper proposes the use of micro-channeled heat exchangers at both hot and cold sides of the TE module to improve the heat exchange from the working fluids. The authors developed prior works and published papers in the area of fluid flow and heat transfer in microstructures, heat transfer augmentation, and in solar thermal systems. Results obtained show an improved efficiency energy transfer.

Identification of roof areas suited for solar energy conversion systems

1997 ◽  
Vol 11 (1) ◽  
pp. 25-36 ◽  
Author(s):  
H. Wittmann ◽  
P. Bajons ◽  
M. Doneus ◽  
H. Friesinger
Keyword(s):  
Solar Energy ◽  
Energy Conversion ◽  
Solar Energy Conversion ◽  
Energy Conversion Systems
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