A new ocean disposal scenario for anthropogenic CO2: CO2 hydrate formationin a submerged crystallizer and its disposal

A new ocean disposal scenario for anthropogenic CO2 was proposed. The CO2 e mitted from a thermal power plant will be collected and injected into a sub merged crystallizer located at a depth of 450-500 m. In the crystallizer, C O2 will react with the ambient seawater, and be completely converted into C O2 hydrate particles. The hydrate particles so formed will be released into the ocean, and descend to the ocean bottom. During the descending process, the hydrate particles will gradually decompose and release CO2 into the se awater. The remaining hydrate particles will reach the ocean bottom and seq uester there. To study the feasibility of the proposed scenario, an experim ental simulation on the hydrate formation process and a numerical simulatio n on the dissolution and descending behavior of the hydrate particles in th e ocean were conducted. The experiment demonstrated that a proper agitation would be necessary to produce hydrate particles even if the thermodynamic conditions are satisfied for hydrate formation. The formed hydrate particle s agglomerate to a cluster. The apparent density of the cluster increased w ith an increase in the agitation time, and eventually the cluster had negat ive buoyancy in water. The critical agitation time for the buoyancy change increased dramatically with the agitation rate, but was not influenced by t he initial CO2/water ratio. The energy penalty for the crystallization proc ess was estimated to be smaller than 7% for a 100 MW power plant. Numerical simulation on the behavior of the released hydrate particles showed that l arger particles of CO2 hydrate are favorable for less impact on the marine environment due to a longer traveling distance in the ocean before being co mpletely decomposed; (C) 2000 Elsevier Science Ltd. All rights reserved.