NEWS

What goes up must come down — scientists seek to bury CO2

Dozens of scientific institutes, research teams and organizations in the European Union and North America have been researching ways to capture the greenhouse gas of carbon dioxide and bury it underground, spending millions of euros and dollars along the way. While it’s not an easy goal to attain, many experts would like to believe that such solutions are feasible. Greece is one of the countries participating in European programs examining how to bind carbon dioxide and, as in other nations, areas in the country have already been studied with a view to storing, or at any rate imprisoning, carbon dioxide there. The latest developments were presented at the 10th International Geology Conference that took place in Thessaloniki by the head of the Institute of Geology and Mineral Exploration’s (IGME) geothermal division, Giorgos Hadziyiannis. But all the solutions mooted, as Christos Zerefos, professor in atmospheric physics at the University of Athens, pointed out, «come up against the huge cost, and for this reason have been deemed non-feasible.» The ideal solution, from the environmental point of view, Hadziyiannis said, would be for all sources of carbon dioxide emissions, such as coal, gas and natural gas, to be replaced with sustainable energy sources. But this was not a realistic prospect for the near future, he pointed out. EU projections for the share of sustainable energy sources in overall power consumption have it rise from the current 6 percent to 12 percent in 2010. Conventional energy sources will thus continue to produce 80 percent of total energy consumption, with the shortfall made up by nuclear power. Therefore, all the attention is focusing on developing systems to bind carbon dioxide by capturing it at its source and storing it in natural or artificial reservoirs. In Greece, CO2 is chiefly emitted by lignite-burning power stations, vehicles, cement factories, metalworks, fertilizer factories, and others. Binding the gas would involve sequestrating it, then transporting, compressing and putting it in permanent storage in suitable depositories. At the conference, scientists proposed storing the CO2 emitted by factories in geological reservoirs either on land or at sea (at a depth greater than 2,000 meters), injecting it into hothouses, where it would be absorbed by plants and disposing of it in mineral form in suitable rock formations. Major reservoirs With fewer environmental effects, mineral storage has the best prospects for success, said Hadziyiannis, coupled with the fact that the gas is likely to remain longer in the depositories. It has been estimated, for example, that the carbon dioxide produced by the natural gas power station at Komotini in Thrace could be stored for 25 to 30 years in the empty Prinos oil field. Exhausted oil and natural gas fields, old coal, salt and ore mines and deep saltwater aquifers are regarded as the best storage sites. How feasible is all this in Greece? Hadziyiannis gave as an example the CO2 produced by the power plant in Ptolemaida, in northern Greece, which could be stored in a geological reservoir in the Thermaic Gulf. First, however, a number of problems, such as bureaucracy, seismic risk and ecological concerns, coupled with the cost of sequestrating the carbon and transporting it through a network of pipes, would have to be solved. «If carbon-binding solutions were successful, then there would be no reason for a tug of war over the Kyoto Protocol and there would be no reason for the emissions-trading system,» Zerefos pointed out. «There are many scientists who are working in this field around the world,» the professor said, «but they haven’t come up with an answer yet. Carbon dioxide binding can be carried out in many different ways, but it’s a complex process; it can cause other environmental damage and for now, it’s not economically feasible.» The first complete study on carbon management was conducted within the framework of the JOULIE II program by geological and other research institutes. In 1998, the first, large-scale project to store carbon dioxide began in the North Sea (at the exhausted natural gas field of Sleipner off Norway). Over the last three years, research has focused on pilot schemes to store CO2 underground (the WEYBURN and GEODISC projects in Canada and Australia, respectively). At the same time, the EU GESTCO program is undertaking to seek and record suitable depositories, while the NASCENT program is examining the behavior of natural carbon dioxide reservoirs. Geological institutes, within the framework of the CASTOR program, are attempting to improve the technology for sequestrating the gas. Many national projects, in Italy, Germany, Denmark and the USA for instance, are doing the same. Since 2000, IGME has participated in both GESTCO and NASCENT, measuring underground storage capacity in various environments, and undertaking cost estimates by studying various ways of transferring and storing the gas. Greece, it found, has suitable reservoirs with a large storage capacity. The cost, say the IGME scientists, is considerable, with sequestrating the carbon monoxide being the most expensive process. The same applies in all other countries. The NASCENT program is examining the geological characteristics of reservoirs in the Florina area (and in four other states of the EU), with respect to whether the gas can be safely stored, possible leaks due to seismic activity and the resistance of the rock strata to high pressure.