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Abstract

Statement of the Problem: The feasibility of upscaling of microalgae biomass at Norwegian latitudes in greenhouse without artificial illumination nor extra heating as a future sustainable energy source has been evaluated. Methodology & Theoretical Orientation: Two marine(m) and three freshwater(f) algae were cultivated in duplicate, from inoculum batch to upscale in polypropylene open Tray PhotoBioReactor (TPBR, 25 L). Chlorella vulgaris(f), Dunaliella salina(m), Nannochloropsis oculata(m), cultivated for 63 days (20.06.12-23.08.12), and Scenedesmus sp(f), Chlorella wild mix ����rungen(f), cultivated for 42 days (20.07.12-23.08.12), at semi-continuous operation system, enriched CO2 air (3%) and prepared in situ, trifold nitrogen nutrition media (3N-BBM+Vit) and tap water, with volumes replenished when need. Effects investigated: 1. Irradiance and temperature on specific growth rate and daily growth. At 23���°C Scenedesmus sp. grew faster at 0.05 h-1 and fivefold when doubling the irradiation energy input, meanwhile Dunaliella salina, reported 0.024 h-1 and 71.4% growth increase. 2. Outside weather condition in conjugation with irradiation and temperature on oxygen evolution (dissolved, DO) showed that cloudy days generated 31% more DO with 2.64 times less PAR irradiation than sunny days. 3. Optimized Dilution (D) and Mixing (M) regimes on biomass productivity (P) of marine algae increased by 60%. 4. Irradiance (I) on Photosynthetic Efficiency (PE), for marine strains 61% lower irradiance gave 4 times higher PE, and for freshwater strains, a four times lower irradiance gave 4.6 times higher PE. 5. Irradiance on areal CO2 fixation rate, the mean CO2 fixation rate was 55.44 gCO2m-2d-1, which is 2.6 times higher values than found by Hulatt (2011). 6. Outdoors weather conditions on TPBRs energetic efficiency found the overall Irradiation Utilization Efficiency (IUE) provided by the TPBR. Nannochloropsis oculata, performed best with 1.37 gMJ-1, and optical pathway 0.09 m. Conclusion & Significance: A cost-efficient greenhouse microalgae biomass production at northern latitudes shows great potential as sustainable energy supplier e.g., raw ingredients for nutraceutical and animal feed industries.

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