Retrieved discussions and physics reference sources support the concept that solar radiation possesses low thermodynamic entropy, enabling its capacity to drive thermodynamic work and maintain ecological entropy gradients.
Abstract. Understanding the thermodynamic function of life may shed light on its origin. Life, as are all irreversible processes, is contingent on entropy production. Entropy production is a measure of the rate of the tendency of Nature to explore available microstates. The most important irreversible process generating entropy in the biosphere and, thus, facilitating this exploration, is the absorption and transformation of sunlight into heat. Here we hypothesize that life began, and persists today, as a catalyst for the absorption and dissipation of sunlight on the surface of Archean seas. The resulting heat could then be efficiently harvested by other irreversible processes such as the water cycle, hurricanes, and ocean and wind currents. RNA and DNA are the most efficient of all known molecules for absorbing the intense ultraviolet light that penetrated the dense early atmosphere and are remarkably rapid in transforming this light into heat in the presence of liquid water. From this perspective, the origin and evolution of life, inseparable from water and the water cycle, can be understood as resulting from the natural thermodynamic imperative of increasing the entropy production of the Earth in its interaction with its solar environment. A mechanism is proposed for the reproduction of RNA and DNA without the need for enzymes, promoted instead through UV light dissipation and diurnal temperature cycling of the Archean sea-surface.
In the field of solar engineering the practical performance of solar energy conversion devices is generally evaluated strictly on an energy (first law) basis. However, the second law of thermodynamics determines the maximum work potential or exergy content of radiative fluxes independent of any conceptual device. The work in this paper quantifies the effect of directional and spectral distribution of terrestrial solar radiation (SR) on its exergy content. This is particularly important as the thermodynamic character of terrestrial SR is very different from that of blackbody radiation (BR). Exergetic (second law) efficiencies compare the work output of a device to the exergy content of the radiative source flux rather than its energy flux. As a result, exergetic efficiencies reveal that the performance of devices in practice is always better than what is indicated by the corresponding energy efficiency. The results presented in this paper introduce the benefits of using exergy analysis for solar cell design, performance evaluation and optimization.
# Why does sunlight have low entropy?
Tags: thermodynamics, energy, entropy
- Score: 19
- Views: 6817
- Answers: 6
- Answered: yes
- Asked by: Alessandro Power (801 rep)
- Asked: 2024-01-08
- Edited: 2024-01-08
- Site: physics
## Question
This question is inspired from The Sun is giving us a low entropy, not energy.
I accept the claim that sunlight must be a low entropy source of energy, given that it maintains the entropy gradient necessary for life (along with other sustained departures from thermodynamic equilibrium, like weather). We can also show that sunlight is low entropy by comparing its spectrum to a blackbody. Sunlight transmits an energy flux of ~1000W/m² to Earth's surface. Were sunlight a blackbody, then its temperature would be ~360K according to Stefan-Boltzmann. But its actual temperature is closer to 5000K. So sunlight must be far from a blackbody spectrum. (I'm actually not wholly convinced by this last argument. I present it here so that others can point out its flaws.)
Here's my confusion: photons that are emitted in the Sun's core take something like a 100,000 years to reach its surface due to the numerous collision along the way. This ought to thermalize
# Why is Sun's energy entropy low on Earth?
Tags: thermodynamics, entropy, sun
- Score: 3
- Views: 754
- Answers: 2
- Answered: yes
- Asked by: Marinos Eftichiou (33 rep)
- Asked: 2024-07-19
- Edited: 2024-07-26
- Site: physics
## Question
Warning I don't have a physics background, having said that I was recently looking into the sun's radiation energy entropy and I had a couple of questions.
So it is said that we can utilize the energy from the sun on Earth because of its low entropy.
The entropy according to the second law of thermodynamics can be estimated as: $S=\dfrac{E}{T_{sun\_surface}}$ [1]
Now given that the energy received from the sun is exponentially proportional (inverse square law) to the distance from the sun, does it mean that the closer we get to the sun the higher the entropy of the energy of the sun would be? (because the E would get bigger and bigger)
Is this because the earth would heat up faster and faster the closer we get to the sun? what is some intuitive explanation of why this is expected to happen?
Asking because normally I don't see people giving distance as one of the major factors when they explain why the sun has low entropy, eg [2]
Edit:
ok, so
# Where and how is entropy generated in solar energy conversion systems?
arXiv (Cornell University). Published: 2018-02-21. Preprint. 0 citations.
## Abstract
The hotness of the sun and the coldness of the outer space are inexhaustible thermodynamic resources for human beings. From a thermodynamic point of view, any energy conversion systems that receive energy from the sun and/or dissipate energy to the universe are heat engines with photons as the "working fluid" and can be analyzed using the concept of entropy. While entropy analysis provides a particularly convenient way to understand the efficiency limits, it is typically taught in the context of thermodynamic cycles among quasi-equilibrium states and its generalization to solar energy conversion systems running in a continuous and non-equilibrium fashion is not straightforward. In this educational article, we present a few examples to illustrate how the concept of photon entropy, combined with the radiative transfer equation, can be used to analyze the local entropy generation processes and the efficiency limits of different solar energy conversion systems. We provide explicit calculations for the local and total entropy g