Researchers from the University of Southampton say centuries’ worth of carbon dioxide could be safely stored deep beneath the ocean in the basalt rocks of the earth’s upper crust. If such a massive sequestration of fossil fuel emissions turns out to be feasible, further increases in global warming could be averted.
Chiara Marieni, a PhD student based at the National Oceanography Centre in Southampton, studied the properties of CO2 in an effort to develop global maps of the ocean floor to estimate where large volumes of the greenhouse gas could be safely stored.
At high pressures and low temperatures, such as those in deep oceans, carbon dioxide exists as a liquid that is denser and heavier than seawater, Marieni and her colleagues explain. Basalt rock, a key component of the earth’s crust, has a high proportion of empty space and over time may also react with the CO2, locking it into solid calcium carbonate and preventing its release into the oceans or atmosphere.
By estimating temperatures in the upper ocean crust, the researchers were able to identify regions where massive amounts of carbon dioxide could be safely stored. They identified five potential offshore areas in Bermuda, Siberia, South Africa, Japan, and Australia, ranging in size from 2000 square miles (.5 million square kilometers) to nearly 1.5 million square miles (4 million square kilometers). As a precaution, Marieni confined her locations to places having the additional protection of thick layers of impermeable sediments to prevent gas escape.
“We have found regions that have the potential to store decades to hundreds of years of industrial carbon dioxide emissions although the largest regions are far off shore,” said Marieni. “However, further work is needed in these regions to accurately measure local sediment conditions and sample the basalt beneath before this potential can be confirmed.”
Burning fossil fuels has resulted in sharp increases of carbon dioxide in the atmosphere, causing a steady rise in global temperatures. And while new technologies are being developed to capture CO2 at major sources such as power stations, the researchers contend that trapping the harmful gas only works if it is locked away from the atmosphere for centuries.
The new study is published in the journal Geophysical Research Letters.