Final Progress Report: Direct Experiments on the Ocean Disposal of Fossil Fuel CO2.

Abstract

IntroductionFrom 2001 to early 2004, we performed field and laboratory experiments, and developed technology to investigate the feasibility and biological consequences of direct ocean CO2 injection as a sequestration strategy to mitigate rising levels of CO2 in the atmosphere. These activities were performed using support from the Monterey Bay Aquarium Research Institute (MBARI) and DoE, through the combined efforts of MBARI ships, ROVs, and science, engineering and operations personnel. DoE support included funding from NETL (Award DE-FC26-00NT40929 :Feasibility of large-scale ocean CO2 sequestration -Drs. Brewer and Barry) and DoE Office of Science Award DE-FG03-01DF63065 (Direct Experiments on the Ocean Disposal of Fossil Fuel CO 2 -Drs. Barry and Brewer). Activities supported by the Office of Science award were intertwined closely with those funded by NETL and MBARI, but were associated most closely studies by postdoctoral fellows. The major results of activities supported by the NETL award are listed in the attached technical progress report which includes several scholarly publications related to this research. Field ExperimentsSeveral deep-sea field experiments were performed off the California coast during 2001 to 2003. Each of these experiments involved a logistically complicated process of pressurizing and transporting small quantities (~20 to 150 l) of liquid CO2 to the seafloor using the ROV Tiburon, launched from the R/V Western Flyer, operated by MBARI. Five of these small-scale CO2 release experiments were used to evaluate the response of deep-sea organisms to changes in seawater chemistry caused by the addition of CO2 to the ocean. During each experiment, small pools of liquid CO2 were created on the seafloor, after which the CO2 would dissolve slowly into seawater, carrying a CO2-rich dissolution plume downstream over sediments inhabited by infaunal organisms and past small cages holding experimental animals. Changes in seawater chemistry were detected mainly by pH meters; the addition of CO2 to seawater elevates its CO2 levels, and reduces its pH (i.e. increases the acidity of seawater). We assessed the survival of various organisms (microbes, meiofauna [nematodes, amoebae, flagellates], macrofauna [sediment-dwelling worms and crustaceans], and megafauna [snails, sea urchins, sea cucumbers, octopus, fish] during month-long exposure to elevated CO2 levels in the dissolution plumes.The major results of these field experiments indicates that direct ocean injection of CO2 in the deep-sea will have variable, but generally negative effects on deep-sea ecosystems. Elevated CO2 levels cause physiological stress in many marine organisms, including respiratory stress, acidosis of intra-and inter-cellular spaces, and narcosis. The severity of effects on individual physiology vary among taxa, with echinoderms as the most sensitive taxon studies. The potential consequences for population and species level effects remain unknown. Effects will be most pronounced near sites of CO2 release, and the severity and...