(632a) Dewatering of Chlorella through Carbon Dioxide Hydrate Formation for Algal Biofuel Production

Renewable energy alternatives are currently of interest to meet ever-growing energy demands due to fossil fuel depletion and climate change. Biofuels, an alternative source, can be made from a range of organic matter. One option is algae, which can be grown without impacting food production and in a variety of conditions, however the feasibility of converting algae into biofuel is of concern. Dewatering algae is a critical step in the process to make oil extraction more efficient. This study utilizes carbon dioxide clathrate hydrates as a novel process to dewater water-saturated algae solutions. Clathrate hydrates are crystalline solids formed from water molecules that contain trapped gas molecules under high pressure and low temperature conditions. A stainless-steel reactor was built and used to perform proof of concept experiments using Chlorella. Experiments were performed with an initial pressure of 450 psig in a refrigerated circulator cooled to 2°C for three or more days with occasional agitation to encourage carbon dioxide hydrate formation. After performing several experiments, it was found that between 2.3 to 14.4 wt% of free water was converted into clathrate hydrates. Overall, the results show potential for the use of clathrate hydrates to dewater a water-saturated algae solution.