IS SEQUESTRATION THE ANSWER TO CAPTURING CARBON DIOXIDE?
September 21, 2004
Fossil fuels are responsible for emitting 6.5 billion tons of carbon into the air annually, which some scientists claim is responsible for climate change. However, researchers are examining two sequestration process designed to mitigate the effects of carbon dioxide: pumping it underground and enriching the oceans with iron to absorb more CO2.
The process of pumping carbon dioxide into the ground has been used by oil companies since the 1990s to extract more oil from wells. According to researchers:
- Underground storage may hold hundreds of years worth of carbon dioxide.
- In 1999, a Calgary-based oil company launched a 30-year project with researchers to pump 20 million metric tons of CO2 into an old oil reservoir; since then, researchers note that the CO2 has not surfaced.
- Norway launched a sequestration project in 1996 which has successfully injected about 1 million tons of CO2 per year back into a layer of porous sandstone.
Additionally, researchers have experimented with iron enrichment, which involves adding iron to ocean water to enhance the growth of phytoplanktons (algae), which absorb carbon dioxide. While such areas show measurable increases in the absorption of carbon dioxide, ocean waters with high-silicate concentrations (a salt from silica) fared better than those with low-silicate concentrations.
However, both procedures have drawbacks. Pumping carbon dioxide into the ground is costly, adding about 2 to 3 cents per kilowatt-hour to consumer electricity delivered, or the equivalent of about one-third of the average residential electric bill.
Furthermore, iron enrichment, while producing measurable results, may not be sufficient enough to reduce current carbon dioxide emissions.
Source: Robert F. Service, "The Carbon Conundrum," Science, Vol. 305, Issue 5686, 962-963, August 13, 2004; Kenneth H. Coale et al., "Southern Ocean Iron Enrichment Experiment: Carbon Cycling in High-and Low-Si Waters," Science, Vol. 304, Issue 5669, 408-414 , April 16, 2004; and Ken O. Buesseler et al., "The Effects of Iron Fertilization on Carbon Sequestration in the Southern Ocean," Science, Vol. 304, Issue 5669, 414-417, April 16, 2004.
For Service text (subscription required): http://www.sciencemag.org/cgi/content/full/305/5686/962
For Coale text (subscription required) http://www.sciencemag.org/cgi/content/full/304/5669/408
For Buesseler text (subscription required) http://www.sciencemag.org/cgi/content/full/304/5669/414
Browse more articles on Environment Issues