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A genset and mini-photobioreactor association for CO2 capturing, enhanced microalgae growth and multigeneration

Telles, E.C., Yang, S., Vargas, J.V.C., Dias, F.G., Ordonez, J.C., Mariano, A.B., Chagas, M.B., Davis, T.
Renewable energy 2018 v.125 pp. 985-994
Scenedesmus, air, biodiesel, biomass, carbon dioxide, combustion, diesel engines, diesel fuel, drying, electric power, emissions, flocculation, fuel production, harvesting, microalgae, oils, transesterification, waste heat recovery
A multigeneration system is proposed to recover waste heat from a genset driven by a diesel engine, and capture CO2 in its emissions for microalgae growth. Scenedesmus sp. and an algae mixture were separately cultivated in 20-L jugs by supplying two CO2 sources: air and diesel engine emissions. Microalgae growth rates were determined from absorbances and analyzed to construe whether emissions in lieu of air enhanced the microalgae growth. Also, a mini-photobioreactor (mPBR) was employed to grow local algae mixture with air and emissions as CO2 sources. The experimental results demonstrated that diesel engine emissions increased the growth of both Scenedesmus sp. and local algae mixture. The multigeneration system thermal efficiency was defined as the sum of the total electrical power produced for cultivation in PBR, biomass harvesting, flocculation, separation, drying and oil extraction, followed by biodiesel production via transesterification reaction, plus the waste heat recovery and the heat generation rate potential of the produced biodiesel, divided by the heat input rate due to the combustion of consumed diesel fuel. In the absence of waste heat recovery, maximum thermodynamic efficiency of the system was 26%, while it increased to 36.2% with waste heat recovery and microalgae biodiesel, i.e., by 39.2%.