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Title: Aspects of feasibility of a shipboard algal photobioreactor to capture carbon dioxide emissions
Author: Koutita, K.
ISNI:       0000 0004 8499 3598
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2017
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The CO2 contribution of shipping to global emissions is about 3.1% and emission reductions are becoming urgent as part of global measures to combat air pollution. This study was the first to investigate the implementation of an algal photobioreactor (PBR) on a ship to treat its gas emissions and produce biomass for commercial purposes. The research examined various aspects of the challenges faced, focusing on the biomass cultivation process of the application. The target was to use the waste streams of the ship (i.e., flue gas, waste heat and wastewater) to fulfil the PBR's material and energy needs. A PBR configuration is proposed and constructed, considering the additional complications of a shipboard system. Algae from natural surrounding water were cultivated in lab conditions to explore the potential of this approach in a shipboard PBR. A theoretical hydrodynamic model was developed to compute gas hold-up and liquid velocity in airlift PBRs. The different bubble sizes and drag coefficients used were shown to greatly impact the results, but the effect of bubbles is not easily distinguished in the experiments. A model of the effects of light intensity, nutrient concentration and temperature on microalgal growth kinetics was also developed, for use in optimising the operating conditions. Finally, practical aspects of integrating the PBR into the shipboard system were examined. Availability of space in the ballast tanks of tankers and ferries in the existing fleet to accommodate a PBR to treat their total emissions was estimated. The need for a large water mass limits this application, but the comparatively higher potential of tankers for this implementation was demonstrated. Maintaining the PBR's temperature by sparging with hot flue gas was proven to be unfeasible and a novel heat exchanger design was suggested and modelled, using an input produced by the hydrodynamic model.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available