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Energy conversion efficiencies of green algae for hydrogen and oxygen production [4] *The entries in this column correspond to the ordinal number of successive periods of illumination. The light was on for either a 3- or 4-h period, after an equal period of darkness. *The entries in this column correspond to the ordinal number of successive periods of illumination. The light was on for either a 3- or 4-h period, after an equal period of darkness. >Conversion efficiency based on absorbed photosynthetically active radiation. PAR =photosynthetically active radiation. Based on repeated measurements and calibrations, it is estimated that the experimental error in these measurements is, at most, +15%. The efficiencies were computed for the rates of hydrogen evolution at the end of the period of illumination when the algae were in a steady (or nearly steady) state.

Table 1 Energy conversion efficiencies of green algae for hydrogen and oxygen production [4] *The entries in this column correspond to the ordinal number of successive periods of illumination. The light was on for either a 3- or 4-h period, after an equal period of darkness. *The entries in this column correspond to the ordinal number of successive periods of illumination. The light was on for either a 3- or 4-h period, after an equal period of darkness. >Conversion efficiency based on absorbed photosynthetically active radiation. PAR =photosynthetically active radiation. Based on repeated measurements and calibrations, it is estimated that the experimental error in these measurements is, at most, +15%. The efficiencies were computed for the rates of hydrogen evolution at the end of the period of illumination when the algae were in a steady (or nearly steady) state.

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Fig. 1. The site of the ‘light reactions’: the thylakoid membrane, linear electron transport and production of adenosine triphosphate (ATP) via a proton driving force.
Fig. 1. The site of the ‘light reactions’: the thylakoid membrane, linear electron transport and production of adenosine triphosphate (ATP) via a proton driving force.
Fig. 2. Photofermentation purple bacteria.
Fig. 2. Photofermentation purple bacteria.
Fig. 4. Sunlight and light absorption by green algae.
Fig. 4. Sunlight and light absorption by green algae.
Fig. 3. Relative intensity on energy basis of sunlight at ground level [9].
Fig. 3. Relative intensity on energy basis of sunlight at ground level [9].
Fig. 5. Sunlight and light absorption by purple bacteria.
Fig. 5. Sunlight and light absorption by purple bacteria.
Fig. 6. Photochemical efficiency of purple bacteria.
Fig. 6. Photochemical efficiency of purple bacteria.
Fig. 8. Comparison of Hy production at locations with different solar irradiance (Amsterdam and Sevilla as examples).
Fig. 8. Comparison of Hy production at locations with different solar irradiance (Amsterdam and Sevilla as examples).
Fig. 7. Horizontal global and direct daily irradiance on ground level in: Amsterdam 52°21’N and Sevilla 37°22’N in 1996 and 1997 according to The European Database of Daylight and Solar Radiation [11].
Fig. 7. Horizontal global and direct daily irradiance on ground level in: Amsterdam 52°21’N and Sevilla 37°22’N in 1996 and 1997 according to The European Database of Daylight and Solar Radiation [11].
Hydrogen production rate, yields and efficiencies of photoheterotrophic bacteria
Hydrogen production rate, yields and efficiencies of photoheterotrophic bacteria
Annotations: (a) given by authors; (b) calculated byourselves; (c)100 1x = 1 Wm~?,according to Ooshima et al. [26]; (d)55.5 Ix = 1 Wm~?, according to Nakada et al. [36]; (+) values calculated for efficiencies are not very accurate because (i) lux and different conversion: to Wm~? can be used, according to the kind of light source and sensor used, or (ii) the irradiation area was roughly estimated. Comments (1) this is the default unit for hydrogen production rate, when other is not indicated; (2) mutant P3, UV irradiation; (3) nitrogen source wa: ammonium salt; (4) carbon source was acetate; (5) carbon source was a mixture of acetate and propionate; (6) semi-continuous, L-malic acid 7.5 mM, sodium glutamate 10 mM; (7) batch, L-malic acid 7.5 mM, sodium glutamate 10 mM; (8) batch, L-malic acid 30 mM, sodiuir glutamate 2 mM; (9) a batch photobioreactor with four flat compartments, see text; (10) carbon source was a mixture of acetate, propionate butyrate and ethanol; (11) efficiency of light conversion to H2 for the long term (66 days); (12) efficiency of light conversion to Hp in the latter stage (8 days); (13) sun light; (14) light irradiation over a period of 12 h expressed in an integral way, by energy per unit of area (15) halogen lamps; (16) with DL-malate 30 mM; (17) with acetate 30 mM; (18) the use of cells immobilized onto light-diffusing optical fibres did not enable the calculation of illuminated area and, consequently, the light efficiency; (19) highest value.
Annotations: (a) given by authors; (b) calculated byourselves; (c)100 1x = 1 Wm~?,according to Ooshima et al. [26]; (d)55.5 Ix = 1 Wm~?, according to Nakada et al. [36]; (+) values calculated for efficiencies are not very accurate because (i) lux and different conversion: to Wm~? can be used, according to the kind of light source and sensor used, or (ii) the irradiation area was roughly estimated. Comments (1) this is the default unit for hydrogen production rate, when other is not indicated; (2) mutant P3, UV irradiation; (3) nitrogen source wa: ammonium salt; (4) carbon source was acetate; (5) carbon source was a mixture of acetate and propionate; (6) semi-continuous, L-malic acid 7.5 mM, sodium glutamate 10 mM; (7) batch, L-malic acid 7.5 mM, sodium glutamate 10 mM; (8) batch, L-malic acid 30 mM, sodiuir glutamate 2 mM; (9) a batch photobioreactor with four flat compartments, see text; (10) carbon source was a mixture of acetate, propionate butyrate and ethanol; (11) efficiency of light conversion to H2 for the long term (66 days); (12) efficiency of light conversion to Hp in the latter stage (8 days); (13) sun light; (14) light irradiation over a period of 12 h expressed in an integral way, by energy per unit of area (15) halogen lamps; (16) with DL-malate 30 mM; (17) with acetate 30 mM; (18) the use of cells immobilized onto light-diffusing optical fibres did not enable the calculation of illuminated area and, consequently, the light efficiency; (19) highest value.
Enclosed photobioreactors; photosynthetic efficiency (PE) and biomass yield on light energy (Yaw,z). After [38] Daily irradiance values in MJm~*d~! were divided by 12 x 3600 s, assuming a day length of 12h, multiplied with 0.429, the fraction PAR in the solar spectrum [10], and multiplied with 4.57, mol photons MJ~! [10]. >Monthly averages of daily solar irradiance on a vertical cylindrical surface in the same period of the year were obtained from the European Database of Daylight and Solar Radiation, www.satel-light.com [11]. Based on a linear growth phase with a productivity of about 0.49 g1~!d—! observed in an outdoor batch culture in three different reactor types. a + oe a ee: . ~— a a sab ee 7 Sey come o i raat Table 3
Enclosed photobioreactors; photosynthetic efficiency (PE) and biomass yield on light energy (Yaw,z). After [38] Daily irradiance values in MJm~*d~! were divided by 12 x 3600 s, assuming a day length of 12h, multiplied with 0.429, the fraction PAR in the solar spectrum [10], and multiplied with 4.57, mol photons MJ~! [10]. >Monthly averages of daily solar irradiance on a vertical cylindrical surface in the same period of the year were obtained from the European Database of Daylight and Solar Radiation, www.satel-light.com [11]. Based on a linear growth phase with a productivity of about 0.49 g1~!d—! observed in an outdoor batch culture in three different reactor types. a + oe a ee: . ~— a a sab ee 7 Sey come o i raat Table 3
Fig. 9. The design of the large-scale flat-plate photobioreactor.
Fig. 9. The design of the large-scale flat-plate photobioreactor.
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ChemistryFood ScienceBiologyMedicineHydrogen ProductionBiohydrogen ProductionChlorella Vulgaris
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