Carbon dioxide (CO2) emissions are one of the main causes of air pollution and global climate change; consequently, current research focuses on finding ways to reduce CO2 emissions or reusing them. Additionally, the increasing energy demand has provided the impetus for developing alternative energy sources; with an emphasis on renewables. Bioenergy from microalgae has captured the attention of researchers given that they efficiently convert CO2 directly captured from the air into energy. Extrapolating the concept of how algae obtain the carbon source to produce energy, this thesis main goal is to examine the feasibility of using direct air capture as a mean for replenishing CO2 supply in the medium used for microalgal cultivation, converting the CO2 harvested from the atmosphere into biomass at high pH and high alkalinity conditions. The proposed capture unit is a packed absorption column, and was studied both from an experimental and modeling point of view. The laboratory-scale unit was able to capture ~50% of the CO2 in the inlet stream using the spent algal cultivation medium. Experimental results were used to adjust model parameters and to further validate model predictions. After the experimental validation, this model was successfully used to design a unit that can meet the desired CO2 requirements for microalgal cultivation. The column specifications include design parameters, such as packing, and the overall column dimensions to fulfill the specified demand. The model is able to predict, with a 98% reliability, the column’s performance for variations in process conditions which include pH level, air temperature, humidity, and CO2 concentration in the inlet. This model considers the actual rates of multicomponent mass transfer, heat transfer and chemical reactions which are taken into account simultaneously. Pressure drop along the absorption column was ~1% of the inlet pressure, which translates in reduced energy consumption. Water losses in the air capture unit were estimated to be under 1% of the water circulating in the system, which is significantly less than the water losses estimated for traditional open pond cultivation systems.