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CO2 Effects on Growth and Lipid Composition of Microalgae

This scientific study explores the effects of CO2 concentrations on the growth and lipid composition of microalgae, specifically Chlorella vulgaris and Pleurochrysis cf. pseudoroscoffensis. The findings highlight the potential of microalgae as a renewable energy source and its significance in reducing CO2 emissions.

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CO2 Effects on Growth and Lipid Composition of Microalgae

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  1. Caffè Scientifico Sezione di Oceanografia ALGAL BIOMASS AND RENEWABLE ENERGY: CO2 EFFECTS ON GROWTH AND LIPID COMPOSITION OF MICROALGAE Federica Cerino gruppo MaB – Biologia Marina 27 maggio 2014

  2. Energy-Environment • Horizon 2020: • -20% CO2 • +20% energy efficiency • +20% renewable energy Doha Conference 80% OF GLOBAL ENERGY DEMAND IS PRODUCED FROM FOSSIL FUEL [CO2] = from 326 ppm (1970) to 395ppm (2013) Kyoto Protocol (1997)

  3. Biomass Organic material, animal or vegetal • Biogas • Bioethanol • Biohydrogen • Pure vegetal oil • Biodiesel • Heat • Electricity

  4. Biodiesel Mixture of fatty acyd alkyl esters, obtained from vegetable oils and animal fats TRANSESTERIFICATION triglycerides alcohol glycerol fatty acid alkyl esters ADVANTAGES: - closed carbon cycle - highly biodegradable - renewable - minimal toxicity - it can be used in existing diesel engines with little or no modification

  5. Biodiesel • 3th generation • microalgae • 2nd generation (non-edible) • jatropha • mahua • jojoba oil • tobacco seed • salmon oil • sea mango • waste cooking oil • restaurant grease • animal fats • 1st generation (edible) • corn • sugar cane • sunflower • rapeseed • soybeans • palm oil

  6. Microalgae Microalgae are prokaryotic and eukaryotic photosynthetic organisms They are present in all earth ecosystem (aquatic and terrestrial) and live in a wide range of environmental conditions They reproduce themselves using photosynthesis to convert sun energy into chemical energy They are responsible for about half of the global net primary production They have a high efficiency in the CO2 fixation It is estimated that more than 50,000 species exist, but only around 30,000 have been studied and analysed (Richmond, 2004)

  7. Microalgae Easy to cultivate Tolerate sub-optimal conditions High growth rates and productivity Require much less land area High oil content High oil yield

  8. Microalgae Mata et al., 2010

  9. Microalgae - Biodiesel growth medium/nutrient concentration light temperature pH air/CO2 Mata et al., 2010

  10. Microalgae - Biodiesel LIPID CONTENT BIOMASS CRESCITA

  11. Aim To analyze the answers of two microalgae to different CO2 concentrations CELL GROWTH LIPID CONTENT Chlorella vulgaris Pleurochrysis cf. pseudoroscoffensis

  12. Material & Methods air CO2 gas mixer illumination pH controller • 2 cylindrical photobioreactors, in plexiglass • 20 L max volume • photoperiod controller • pH controller • gas-mixer

  13. Material & Methods Chlorella (green algae) Chlorophyceae • Generally unicellular and colonial, but also pluricellular • Abundant in freshwater environments Chlorella vulgaris • Highly resistant • Easily cultivable with a high growth rate • Used for: • CO2 sequestration • Wastewater depuration • Nutritional supplement • Applications in human health

  14. Material & Methods air CO2 gas mixer cellular growth • cell abundances • growth rate • duplication time • maximum concentration illumination pH controller Chlorella (green algae) lipid content • total lipid content • fatty acid composition control CO2 1% T=20 ± 1°C L:D=12:12 light=250-300 µE m-2s-1

  15. Results C CO2 Chlorella (green algae) Max= 36 ·106 cell ml-1 µ= 1.17 d-1 T2= 14 Max= 32 ·106 cell ml-1 µ= 1.38 d-1 T2= 12

  16. Results C CO2 C CO2 C CO2 Chlorella (green algae)

  17. Material & Methods 5 µm 10 µm Pleurochrysis (coccolithophore) Coccolithophores (Prymnesiophyceae) • calcareous nanophytoplankton • with external calcite (CaCO3) plates (coccoliths) covering their surface • Play key roles in: • marine ecosystem as primary producers • marine biogeochemistry as producers of organic carbon, carbonate and dimethylsulphide Pleurochrysis cf. pseudoroscoffensis • marine species isolated in the Gulf of Trieste

  18. Material & Methods air CO2 gas mixer cellular growth • cell abundances • growth rate • duplication time • maximum concentration illumination lipid content • total lipid content • fatty acid composition morphometric analysis • cellular size chemical parameters pH controller • nutrients • POC/PIC/PTN • pH Pleurochrysis (coccolithophore) • coccolith size CO2 1% CO2 2% control

  19. Results C CO2 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 day day Pleurochrysis (coccolithophore) CO2 1% CO2 2% pH= 8.4 ± 0.3 pH= 7.5 ± 0.2 pH= 8.1 ± 0.4 pH= 7.1 ± 0.1 p <0.05 Max= 2.86 ·105 cell ml-1 µ= 0.86 d-1 T2= 19 Max= 4.32 ·105 cell ml-1 µ= 1.01 d-1 T2= 16 Max= 2.71 ·105 cell ml-1 µ= 0.82 d-1 T2= 20 Max= 3.85 ·105 cell ml-1 µ= 1.06 d-1 T2= 16

  20. Results C CO2 0 0 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9 day day Pleurochrysis (coccolithophore) CO2 1% CO2 2%

  21. Results C CO2 day day day day Pleurochrysis (coccolithophore) CO2 1% CO2 2%

  22. Results C CO2 10 µm 10 µm 10 µm 10 µm Pleurochrysis (coccolithophore) CO2 1% CO2 2%

  23. Results Pleurochrysis (coccolithophore) CO2 1% CO2 2%

  24. Conclusions Chlorella (green algae) • higher growth rate • higher number of divisions per day • higher lipid content • Potential utilization in biodiesel production Pleurochrysis (coccolithophore) In both experiments (1 and 2% CO2): • biomass increase • higher growth rate • higher number of division per day • slight effect on morphology In the experiment with CO2 2%, the maximum of biomass was reached earlier Potential utilization in CO2 removal

  25. Perspectives • To test other species and strains • To search for the best growth conditions to have higher lipid synthesis and higher cell growth • To test the effects of other culture conditions (light, salinity, nutrients, temperature) • To test the combined effects of several different factors to analyze their eventual sinergy in the lipid production

  26. Perspectives Animal feed Proteins Nutritional supplement Ethanol Carbohydrates wastewater Biodiesel light CO2 Cosmetic Lipids nutrients HARVESTING PROCESSING BIOREFINERY

  27. THANK YOU • Si ringraziano per la collaborazione: • Cinzia Comici • Martina Kralj • Gianmarco Ingrosso • Ana Karuza • Cinzia Fabbro • Cinzia De Vittor • Michele Giani • Prof. Bogoni, UNITS • Prof. Procida, UNITS • Dott. Urbani, UNITS Parte di questo studio è inserito nel progetto CO2 Monitor

  28. Results C CO2 0 0 0 0 1 1 1 1 2 2 2 2 3 3 3 3 4 4 4 4 5 5 5 5 6 6 6 6 7 7 7 7 8 8 8 8 9 9 9 9 day day day day Pleurochrysis (coccolithophore) CO2 1% CO2 2%

  29. Perspectives la produzione di biodiesel da microalghe non è ancora una realtà commercialmente significativa • abbattimento dei costi relativi alla somministrazione di nutrienti, tramite il trattamento delle acque reflue e l’utilizzo dei nutrienti in esse presenti • abbattimento dei costi relativi alla somministrazione di CO2, tramite il recupero e utilizzo dei gas di scarico industriali come fonte della CO2 necessaria alla crescita • abbattimento del dispendio idrico necessario al mantenimento delle colture tramite riciclo dei mezzi • miglioramento delle tecniche per il processamento della biomassa, soprattutto per quanto riguarda la fase di raccolta • applicazione di tecniche di ingegneria genetica per incrementare l’efficienza fotosintetica e quindi il rendimento della biomassa, il miglioramento del tasso di crescita, del contenuto in olio, e della tolleranza alla temperatura • risoluzione del problema dell’applicazione su larga scala dei risultati ottenuti in laboratorio (scaling-up); allestimento di impianti pilota su larga scala da cui ottenere dati che possano essere usati per valutazioni di fattibilità economica

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