Calculation of light penetration depth in photobioreactors

Lee, Choul-Gyun

doi:10.1007/bf02931920

Cited by 95 publications

(53 citation statements)

References 12 publications

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“…In Chlorella cultures, light absorption is well represented by the Beer-Lambert law at a variety of cellular densities, without the necessity for consideration of reflectance (Lee, 1999). The difference in reflective properties between a leaf and an algal culture could be the result of both the decreased differences in refractive indices between the algal cell (1.047 to 1.092; Spinrad and Brown, 1986) and the aqueous culture medium (1.33) compared to leaves and the less cell-dense culture conditions, which minimize cell-tomedium light scattering.…”

Section: Tradeoffs Between Leaf Reflectance and Transmittance Limit Tmentioning

confidence: 99%

Chlorophyll Can Be Reduced in Crop Canopies with Little Penalty to Photosynthesis

et al. 2017

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The hypothesis that reducing chlorophyll content (Chl) can increase canopy photosynthesis in soybeans was tested using an advanced model of canopy photosynthesis. The relationship among leaf Chl, leaf optical properties, and photosynthetic biochemical capacity was measured in 67 soybean (Glycine max) accessions showing large variation in leaf Chl. These relationships were integrated into a biophysical model of canopy-scale photosynthesis to simulate the intercanopy light environment and carbon assimilation capacity of canopies with wild type, a Chl-deficient mutant (Y11y11), and 67 other mutants spanning the extremes of Chl to quantify the impact of variation in leaf-level Chl on canopy-scale photosynthetic assimilation and identify possible opportunities for improving canopy photosynthesis through Chl reduction. These simulations demonstrate that canopy photosynthesis should not increase with Chl reduction due to increases in leaf reflectance and nonoptimal distribution of canopy nitrogen. However, similar rates of canopy photosynthesis can be maintained with a 9% savings in leaf nitrogen resulting from decreased Chl. Additionally, analysis of these simulations indicate that the inability of Chl reductions to increase photosynthesis arises primarily from the connection between Chl and leaf reflectance and secondarily from the mismatch between the vertical distribution of leaf nitrogen and the light absorption profile. These simulations suggest that future work should explore the possibility of using reduced Chl to improve canopy performance by adapting the distribution of the "saved" nitrogen within the canopy to take greater advantage of the more deeply penetrating light.

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Section: Tradeoffs Between Leaf Reflectance and Transmittance Limit Tmentioning

confidence: 99%

Chlorophyll Can Be Reduced in Crop Canopies with Little Penalty to Photosynthesis

et al. 2017

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“…The net growth of the algae culture at very low light intensities is zero (compensation point) (Lee 1997). With increase in light intensities, photosynthesis increases until a point is reached where the growth rate is the maximum attainable (saturation point) (Goldman 1979;Lee 1999;Richmond 2000). Increasing the light intensity beyond this point does not increase the growth rate and can lead to photo-oxidation, damaging the light receptors and thereby, decreasing the photosynthetic rate and productivity (photo inhibition).…”

Section: Environmental Conditions For Microalgae Biomass Productionmentioning

confidence: 99%

Microalgae as second generation biofuel. A review

Singh¹,

Dhar²

2011

Agron. Sustain. Dev.

144

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Microalgae are autotrophic microorganisms having extremely high photosynthetic efficiency and are valued as rich source of lipids, hydrocarbons, and other complex oils for biodiesel besides being an invaluable source of bioethanol, biomethane, and biohydrogen. Biodiesel produced from oilseed crops such as jatropha and soy have lower yields per unit land area and threaten food security. Indeed, microalgae have higher oil yields amounting to about 40 times more oil per unit area of land in comparison to terrestrial oilseed crops such as soy and canola. Further, microalgae production does not require arable land for cultivation. Biofuel is regarded as a proven clean energy source and several entrepreneurs are attempting to commercialize this renewable source. Technology for producing and using biofuel has been known for several years and is frequently modified and upgraded. In view of this, a review is presented on microalgae as second generation biofuel. Microalgal farming for biomass production is the biggest challenge and opportunity for the biofuel industry. These are considered to be more efficient in converting solar energy into chemical energy and are amongst the most efficient photosynthetic plants on earth. Microalgae have simple cellular structure, a lipid-rich composition, and a rapid rate of reproduction. Many microalgal strains can be grown in saltwater and other harsh conditions. Some autotrophic microalgae can also be converted to heterotrophic ones to accumulate high quality oils using organic carbon. However, there are several technical challenges that need to be addressed to make microalgal biofuel profitable. The efficiency of microalgal biomass production is highly influenced by environmental conditions, e.g., light of proper intensity and wavelength, temperature, CO 2 concentration, nutrient composition, salinities and mixing conditions, and by the choice of cultivation systems: open versus closed pond systems, photobioreactors. Currently, microalgae for commercial purpose are grown mostly in open circular/elongated "raceway" ponds which generally have low yields and high production costs. However, a hybrid system combining closed photobioreactor and open pond is a better option. The biggest hurdle in commercialization of microalgal biofuel is the high cost and energy requirement for the microalgal biomass production, particularly agitation, harvesting, and drying of biomass. In order to conserve energy and reduce costs, algae are often harvested in a two-step process involving flocculation followed by centrifugation, filtration, or micro-straining to get a solid concentration. However, the major bottlenecks in algal biodiesel production within the cell can be identified and handled by adopting a system approach involving transcriptomics, proteomics, and metabolomics. Research and developments in the field of new materials and advanced designs for cultivation in closed bioreactors, use of waste water for biomass production, screening of efficient strains, high-value coproduct strategy,...

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“…This mutual shading or self-shading will shield the cells that are apart from the illumination surface from receiving light. As a result, the light penetration depth should be calculated in order to achieve a successful photobioreactor (Lee, 1999). One of the solutions was to create a turbulent flow by installing static mixers.…”

Section: Applications In Bioreactors and Culturesmentioning

confidence: 99%