Evaluation of the Environmental Viability of Direct Injection Schemes for Ocean Carbon Sequestration

This thesis evaluates the expected impact of several promising schemes for ocean carbon sequestration by direct injection of CO 2, and serves as an update to the as-sessment by Auerbach et al. (1997) and Caulfield et al. (1997) of water quality impacts and the induced mortality to zooplankton. The present work extends the methodol-ogy used in the earlier studies, incorporates recent acute CO 2 toxicity data on marine organisms, and considers three revised discharge approaches: a point release of neg-atively buoyant CO 2 hydrate particles from a moving ship; a long, bottom-mounted diffuser discharging buoyant liquid CO 2 droplets; and a stationary point release of hydrate particles forming a sinking plume. Results suggest that it is possible with present technology to engineer discharge configurations which achieve sufficient dilu-tion to largely avoid acute impacts. Sub-lethal and ecosystem effects are discussed qualitatively, but not analyzed quantitatively. The analysis suggests that, as a tem-porary climate change mitigation strategy, ocean carbon sequestration by direct in-jection should not be dismissed on the basis of environmental impact alone. Wit