Microalgal industrial production requires high surface area, resulting in production costs curren... more Microalgal industrial production requires high surface area, resulting in production costs currently unacceptable. A possible optimization of land use for the cultivation of Scenedesmus obliquus is proposed, by conjoint production of biomass and electricity using photovoltaic cells (PV). For this purpose, biomass cultivation in a continuously operated 1 hectare open pond placed inside a greenhouse was considered, at two different Italian latitudes, as case studies. The greenhouse roof surface was partially covered with commercial PV modules, resulting in a reduced average irradiation. The light profiles and the average temperatures inside the greenhouse were simulated for different seasons, and the corresponding microalgal productivities were calculated based on a validated growth model. The partial pond shading limited photoinhibition in summer at Southern location, resulting in higher productivities. On the other hand, the loss of sunlight, due to the partial roof covering, resulted in a lower productivity in the other cases and for the Northern location. The presence of PV, however, allowed a better exploitation of light to produce electricity, which supports the energy duties of the process, with an additional net electricity production. Finally, an economic analysis was carried out showing a reduction of biomass production costs when PV is present.
Microalgal industrial production requires high surface area, resulting in production costs curren... more Microalgal industrial production requires high surface area, resulting in production costs currently unacceptable. A possible optimization of land use for the cultivation of Scenedesmus obliquus is proposed, by conjoint production of biomass and electricity using photovoltaic cells (PV). For this purpose, biomass cultivation in a continuously operated 1 ha open pond placed inside a greenhouse was considered, at two different Italian latitudes, as case studies. The greenhouse roof surface was partially covered with commercial PV modules, resulting in a reduced average irradiation. The light profiles and the average temperatures inside the greenhouse were simulated for different seasons, and the corresponding microalgal productivities were calculated based on a validated growth model. The partial pond shading limited photoinhibition in summer at Southern location, resulting in higher productivities. On the other hand, the loss of sunlight, due to the partial roof covering, resulted in a lower productivity in the other cases and for the Northern location. The presence of PV, however, allowed a better exploitation of light to produce electricity, which supports the energy duties of the process, with an additional net electricity production. Finally, an economic analysis was carried out showing a reduction of biomass production costs when PV is present.
The use of bicarbonate as carbon supply in a large scale photobioreactor for industrial microalga... more The use of bicarbonate as carbon supply in a large scale photobioreactor for industrial microalgae production could reduce the compression and transportation costs associated with the direct use of CO 2 from flue gas. Some microalgae species are able to directly exploit bicarbonate as a carbon source, but the actual yield in view of large scale production is not clear, in particular for eukaryotic and lipid-rich strains. In this work, the exploitation of bicarbonate as carbon source by Chlorella protothecoides was critically assessed. Both batch and continuous experiments were carried out with the addition of NaHCO 3 to the culture medium. The growth of this species was found to be strongly affected by the increased pH, resulting in a reduced yield if compared with that from an air−CO 2 bubbling supply. To overcome this issue, a pH control system was applied, so that the pH value was maintained below 8. In these conditions a specific growth rate was measured close to that obtained under CO 2 bubbling, probably due to the equilibrium of carbonate, which is shifted to H 2 CO 3 and free CO 2 . Thus, it appears that C. protothecoides is not able to directly use bicarbonate, but exploits the CO 2 made available from the shifting of the carbonate equilibrium. In addition, the presence of bicarbonate also caused a lipid accumulation in C. protothecoides, up to about 40% dry weight, compared to the constitutive value of 10−12% dry weight. On the basis of the results obtained, a process scheme was proposed, integrating microalgae cultivation with CO 2 capture by absorption with a recirculating carbonate solution. Process simulation was carried out to show the technical feasibility of this process.
This paper investigates the use of infinite-dilution activity coefficients to define the interact... more This paper investigates the use of infinite-dilution activity coefficients to define the interaction parameters of the Redlich-Kwong equation of state (SRK-EOS), with the Huron-Vidal mixing rules. The group-contributions of a UNIFAC-type model were regressed from experimental infinitedilution activity coefficients of a number of significant systems, including strongly polar components. Such parameters were then used to predict vapor-liquid equilibria (VLE) over the whole composition range, at pressures up to 6 MPa, with generally good results. Abstract published in Aduance ACS Abstracts, March 1, 1994. 50 40
Microalgal industrial production requires high surface area, resulting in production costs curren... more Microalgal industrial production requires high surface area, resulting in production costs currently unacceptable. A possible optimization of land use for the cultivation of Scenedesmus obliquus is proposed, by conjoint production of biomass and electricity using photovoltaic cells (PV). For this purpose, biomass cultivation in a continuously operated 1 hectare open pond placed inside a greenhouse was considered, at two different Italian latitudes, as case studies. The greenhouse roof surface was partially covered with commercial PV modules, resulting in a reduced average irradiation. The light profiles and the average temperatures inside the greenhouse were simulated for different seasons, and the corresponding microalgal productivities were calculated based on a validated growth model. The partial pond shading limited photoinhibition in summer at Southern location, resulting in higher productivities. On the other hand, the loss of sunlight, due to the partial roof covering, resulted in a lower productivity in the other cases and for the Northern location. The presence of PV, however, allowed a better exploitation of light to produce electricity, which supports the energy duties of the process, with an additional net electricity production. Finally, an economic analysis was carried out showing a reduction of biomass production costs when PV is present.
Microalgal industrial production requires high surface area, resulting in production costs curren... more Microalgal industrial production requires high surface area, resulting in production costs currently unacceptable. A possible optimization of land use for the cultivation of Scenedesmus obliquus is proposed, by conjoint production of biomass and electricity using photovoltaic cells (PV). For this purpose, biomass cultivation in a continuously operated 1 ha open pond placed inside a greenhouse was considered, at two different Italian latitudes, as case studies. The greenhouse roof surface was partially covered with commercial PV modules, resulting in a reduced average irradiation. The light profiles and the average temperatures inside the greenhouse were simulated for different seasons, and the corresponding microalgal productivities were calculated based on a validated growth model. The partial pond shading limited photoinhibition in summer at Southern location, resulting in higher productivities. On the other hand, the loss of sunlight, due to the partial roof covering, resulted in a lower productivity in the other cases and for the Northern location. The presence of PV, however, allowed a better exploitation of light to produce electricity, which supports the energy duties of the process, with an additional net electricity production. Finally, an economic analysis was carried out showing a reduction of biomass production costs when PV is present.
The use of bicarbonate as carbon supply in a large scale photobioreactor for industrial microalga... more The use of bicarbonate as carbon supply in a large scale photobioreactor for industrial microalgae production could reduce the compression and transportation costs associated with the direct use of CO 2 from flue gas. Some microalgae species are able to directly exploit bicarbonate as a carbon source, but the actual yield in view of large scale production is not clear, in particular for eukaryotic and lipid-rich strains. In this work, the exploitation of bicarbonate as carbon source by Chlorella protothecoides was critically assessed. Both batch and continuous experiments were carried out with the addition of NaHCO 3 to the culture medium. The growth of this species was found to be strongly affected by the increased pH, resulting in a reduced yield if compared with that from an air−CO 2 bubbling supply. To overcome this issue, a pH control system was applied, so that the pH value was maintained below 8. In these conditions a specific growth rate was measured close to that obtained under CO 2 bubbling, probably due to the equilibrium of carbonate, which is shifted to H 2 CO 3 and free CO 2 . Thus, it appears that C. protothecoides is not able to directly use bicarbonate, but exploits the CO 2 made available from the shifting of the carbonate equilibrium. In addition, the presence of bicarbonate also caused a lipid accumulation in C. protothecoides, up to about 40% dry weight, compared to the constitutive value of 10−12% dry weight. On the basis of the results obtained, a process scheme was proposed, integrating microalgae cultivation with CO 2 capture by absorption with a recirculating carbonate solution. Process simulation was carried out to show the technical feasibility of this process.
This paper investigates the use of infinite-dilution activity coefficients to define the interact... more This paper investigates the use of infinite-dilution activity coefficients to define the interaction parameters of the Redlich-Kwong equation of state (SRK-EOS), with the Huron-Vidal mixing rules. The group-contributions of a UNIFAC-type model were regressed from experimental infinitedilution activity coefficients of a number of significant systems, including strongly polar components. Such parameters were then used to predict vapor-liquid equilibria (VLE) over the whole composition range, at pressures up to 6 MPa, with generally good results. Abstract published in Aduance ACS Abstracts, March 1, 1994. 50 40
Uploads
Papers by Luca Vecchiato