Typical efficiencies Photosynthetic efficiency

1 typical efficiencies

1.1 plants
1.2 algae , other monocellular organisms

1.2.1 worldwide figures

typical efficiencies
plants

quoted values sunlight-to-biomass efficiency

the following breakdown of energetics of photosynthesis process photosynthesis hall , rao:

starting solar spectrum falling on leaf,

47% lost due photons outside 400–700 nm active range (chlorophyll utilizes photons between 400 , 700 nm, extracting energy of 1 700 nm photon each one)

30% of in-band photons lost due incomplete absorption or photons hitting components other chloroplasts

24% of absorbed photon energy lost due degrading short wavelength photons 700 nm energy level

68% of utilized energy lost in conversion d-glucose

35–45% of glucose consumed leaf in processes of dark , photo respiration

stated way:

100% sunlight → non-bioavailable photons waste 47%, leaving

53% (in 400–700 nm range) → 30% of photons lost due incomplete absorption, leaving

37% (absorbed photon energy) → 24% lost due wavelength-mismatch degradation 700 nm energy, leaving

28.2% (sunlight energy collected chlorophyl) → 32% efficient conversion of atp , nadph d-glucose, leaving

9% (collected sugar) → 35–40% of sugar recycled/consumed leaf in dark , photo-respiration, leaving

5.4% net leaf efficiency.

many plants lose of remaining energy on growing roots. crop plants store ~0.25% 0.5% of sunlight in product (corn kernels, potato starch, etc.).

photosynthesis increases linearly light intensity @ low intensity, @ higher intensity no longer case (see photosynthesis-irradiance curve). above 10,000 lux or ~100 watts/square meter rate no longer increases. thus, plants can utilize ~10% of full mid-day sunlight intensity. dramatically reduces average achieved photosynthetic efficiency in fields compared peak laboratory results. however, real plants (as opposed laboratory test samples) have lots of redundant, randomly oriented leaves. helps keep average illumination of each leaf below mid-day peak enabling plant achieve result closer expected laboratory test results using limited illumination.

only if light intensity above plant specific value, called compensation point plant assimilates more carbon , releases more oxygen photosynthesis consumes cellular respiration own current energy demand.

photosynthesis measurement systems not designed directly measure amount of light absorbed leaf. nevertheless, light response curves class produces allow comparisons in photosynthetic efficiency between plants.

algae , other monocellular organisms

from 2010 study university of maryland, photosynthesizing cyanobacteria have been shown significant species in global carbon cycle, accounting 20–30% of earth s photosynthetic productivity , convert solar energy biomass-stored chemical energy @ rate of ~450 tw.

worldwide figures

according cyanobacteria study above, means total photosynthetic productivity of earth between ~1500–2250 tw, or 47,300–71,000 exajoules per year. using source s figure of 178,000 tw of solar energy hitting earth s surface, total photosynthetic efficiency of planet 0.84% 1.26% (see earth s energy budget).