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Table 5 Comparative energy analyses for biomass or bio-oil production based on 1 year of cultivating M. dybowskii LB50 via different culture modes under OPRs

From: Feasibility of biodiesel production and CO2 emission reduction by Monoraphidium dybowskii LB50 under semi-continuous culture with open raceway ponds in the desert area

Variable 5 m2 200 m2
Batch Induction Semi-continuous Batch Semi-continuous
Annual biomass production (kg year−1) 100,000 100,000 100,000 100,000 100,000
Volumetric productivity (g L−1 day−1) or (kg m−3day−1)a 0.04 0.04 0.07 0.08 0.09
Illuminated areal productivity (kg m−2 day−1)a 0.01 0.01 0.01 0.02 0.02
Reactor volume (m3)b 8413.68 8504.49 5513.10 4700.13 4087.97
Occupied area (m2) 42,087.54 42,522.43 27,557.32 23,500.66 20,439.87
Lipid content (%)a 30.85 39.39 30.84 30.13 30.13
Energy consumption for stirring (W m−3)c 3.72–12.5 3.72–12.5 3.72–12.5 3.72–12.5 3.72–12.5
Total energy for stirring (kWh months−1)d 7511.7–25,241.1 7592.8–25,513.4 4922.1–16,539.3 4196.2–14,100.3 3649.7–12,263.9
Total energy for biomass drying (kWh year−1)e 53,900.00 53,900.00 53,900.00 53,900.00 53,900.00
Total energy for oil recovery (kWh year−1)f 34,534.00 34,534.00 34,534.00 34,534.00 34,534.00
Total energy consumption for producing biomass 437.42–1011.85 440.05–1020.68 353.52–729.91 330–650.89 312.29–591.39
Total energy consumption for producing oil (GJ year−1) 561.74–1136.17 564.37–1145 477.84–854.24 454.32–775.22 436.61–715.71
Energy produced as oil (GJ year−1)g 1204.3 1537.8 1203.9 1176.3 1176.3
Energy produced as 100,000 kg biomass (GJ year−1)h 3155.33 3155.33 3155.33 3155.33 3155.33
NER for oil productioni 2.14–1.06 2.72–1.34 2.52–1.41 2.59–1.52 2.69–1.64
NER for biomass production 7.21–3.12 7.17–3.09 8.93–4.32 9.56–4.85 10.1–5.34
Energy consumption for oil (MJ kg−1 bio-oil) 17.86–36.13 14.06–28.52 15.2–27.17 14.79–25.24 14.22–23.3
Energy consumption for oil (MJ MJ−1 bio-oil) 0.47–0.94 0.37–0.74 0.4–0.71 0.39–0.66 0.37–0.61
  1. The assumed annual biomass production is 100,000 kg
  2. aData were based on this study
  3. bDetermined by dividing the illuminated area actual by production the volume of each unit
  4. c3.72 W m−3 from Jorquera et al. [23]. 12.5 W m−3 from the actual date for the 200 m2 raceway pond
  5. dIncludes 8 h of daily pumping
  6. eStepan et al. [52]. 539 kWh ton−1 biomass
  7. fStephenson et al. [53]; Gao et al. [54]. 345.34 kWh ton−1 biomass
  8. gEnergy content of net oil yield (assumed value of 39.04 MJ kg−1); Jorquera et al. [23]
  9. hEnergy content of net biomass yield (assumed value of 31.55 MJ kg−1); Jorquera et al. [23]
  10. iNER would be above 1 if including coproduct allocation [55]