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
| 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 |
The assumed annual biomass production is 100,000 kg
aData were based on this study
bDetermined by dividing the illuminated area actual by production the volume of each unit
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
dIncludes 8 h of daily pumping
eStepan et al. [52]. 539 kWh ton−1 biomass
fStephenson et al. [53]; Gao et al. [54]. 345.34 kWh ton−1 biomass
gEnergy content of net oil yield (assumed value of 39.04 MJ kg−1); Jorquera et al. [23]
hEnergy content of net biomass yield (assumed value of 31.55 MJ kg−1); Jorquera et al. [23]
iNER would be above 1 if including coproduct allocation [55]