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28.2% (sunlight energy collected by chlorophyll) → 68% is lost in conversion of ATP and NADPH to d-glucose, leaving; 9% (collected as sugar) → 35–40% of sugar is recycled/consumed by the leaf in dark and photo-respiration, leaving; 5.4% net leaf efficiency. Many plants lose much of the remaining energy on growing roots.
Fusing four free protons (hydrogen nuclei) into a single alpha particle (helium nucleus) releases around 0.7% of the fused mass as energy, [68] so the Sun releases energy at the mass–energy conversion rate of 4.26 billion kg/s (which requires 600 billion kg of hydrogen [69]), for 384.6 yottawatts (3.846 × 10 26 W), [5] or 9.192 × 10 10 ...
But of course, other stars also produce radio emission and may produce much more intense radiation in absolute terms than is observed from the Sun. For "normal" main sequence stars, the mechanisms that produce stellar radio emission are the same as those that produce solar radio emission. [ 16 ]
Radiant energy may be developed for solar power generation. Solar irradiation figures are used to plan the deployment of solar power systems . [ 39 ] In many countries, the figures can be obtained from an insolation map or from insolation tables that reflect data over the prior 30–50 years.
Each individual reaction produces only a tiny amount of energy, but because enormous numbers of these reactions occur constantly, they produce all the energy necessary to sustain the star's radiation output. In comparison, the combustion of two hydrogen gas molecules with one oxygen gas molecule releases only 5.7 eV.
The observable universe contains as many as an estimated 2 trillion galaxies [36] [37] [38] and, overall, as many as an estimated 10 24 stars [39] [40] – more stars (and, potentially, Earth-like planets) than all the grains of beach sand on planet Earth. [41] [42] [43] Other estimates are in the hundreds of billions rather than trillions.
The total solar energy absorbed by Earth's atmosphere, oceans and land masses is approximately 122 PW·year = 3,850,000 exajoules (EJ) per year. [12] In 2002 (2019), this was more energy in one hour (one hour and 25 minutes) than the world used in one year. [13] [14] Photosynthesis captures approximately 3,000 EJ per year in biomass. [15]
During a star's evolution, convective mixing episodes moves material, within which the CNO cycle has operated, from the star's interior to the surface, altering the observed composition of the star. Red giant stars are observed to have lower carbon-12/carbon-13 and carbon-12/nitrogen-14 ratios than do main sequence stars, which is considered to ...