Wouldn’t it be wonderful if the nutrient-rich upwelled fluids could be utilized to cultivate a marine microorganism that can take the carbon dioxide from both the effluent and the atmosphere, form a solid carbon compound, and drop it to the bottom of the ocean, to stay there for eons, like millions of years? Well, actually, coccolithophores are single-celled algae, about one-hundredth of a mm in diameter, a hundred million cells per liter, which does exactly that, converting carbon dioxide into carbonate (-CO3). The White Cliffs of Dover, for example, are mostly coccolithophores. Nothing is perfect, of course, as this algae also produce dimethylsulfide, a contributor to global warming, and only a small fraction of its shell ends up as rock at the sea bottom. All in all, though, there is something to this process that intrigues me.
The combination of a floating coal power plant with an OTEC facility to enable deep ocean sequestration of CO2 has been proposed. OTEC uses cold deep sea water as a thermal sink, while ocean sequestration treats it as a repository for anthropogenic (man-made) CO2. These technologies have the potential for synergy, including the sharing of platforms and equipment, addition of CO2 to the warm water OTEC intakes to prevent biofouling of pipelines and heat exchangers, exploiting the negatively buoyant CO2 enriched sea water to drive part of the upward water transport for OTEC, reduction of pumping costs for sequestration, and carbon tax credits.
As an early next step, the International Ocean Alliance Floating Platform Summit suggested a demonstration on a decommissioned oil platform, combining a 10-100 MW fossil fuel power plant, small OTEC system and various associated co-products for testing in Hawaiian waters. In the long term, as OTEC grazing plant ships will be located in the warmest portion of the oceans, where hurricanes are formed, it might be possible to eliminate or reduce the intensity of these ocean storms. We will re-visit this subject in a later section on the Blue Revolution and the environment.