Scientists turn CO2 into rock in climate change fight

Injecting carbon dioxide (CO2)
deep underground and turning it into rock may be a potentially
viable way to tackle increasing greenhouse gas emissions in the
fight against climate change, an international team of scientists
said Thursday.

The study, published in the U.S. journal Science, showed for the
first time that CO2 injected into volcanic bedrock reacts with the
surrounding rock, forming environmentally benign minerals at a
speed faster than anyone had predicted.

Capturing and storing CO2 underground, such as in abandoned oil
and gas reservoirs, is widely considered a crucial strategy for
meeting CO2 emission reduction targets, but doing so creates a risk
of carbon leakage.

So attention has now turned to the mineralization of carbon to
permanently dispose of CO2, a process scientists previously thought
would take several hundreds to thousands of years.

But the new study, led by Columbia University, University of
Iceland, University of Toulouse and Reykjavik Energy, now
demonstrated that it can take as little as two years.

“Our results show that between 95 and 98 percent of the injected
CO2 was mineralized over the period of less than two years, which
is amazingly fast,” Lead author Juerg Matter, Associate Professor
in Geoengineering at the University of Southampton, said in a
statement.

The new project called CarbFix was started in 2012 in Iceland, a
volcanic island made up of 90 percent basalt, which is formed by
volcanic activity and rich in elements such as calcium, magnesium
and iron that are required for carbon mineralization.

The gas was dissolved in water and then injected into a deep
well at Iceland’s study site. On contact with the target storage
rocks, at 400 to 800 meters under the ground, the solution quickly
reacts with the surrounding basaltic rock, forming carbonate
minerals.

“Carbonate minerals do not leak out of the ground, thus our
newly developed method results in permanent and environmentally
friendly storage of CO2 emissions,” said Matter, who is also
adjunct senior scientist at Lamont-Doherty Earth Observatory,
Columbia University.

“On the other hand, basalt is one of the most common rock type
on Earth, potentially providing one of the largest CO2 storage
capacity,” Matter said.

CarbFix was a relatively small test, so the team’s next step was
to upscale CO2 storage in basalt.

According to the study, this is currently happening at Reykjavik
Energy’s Hellisheidi geothermal power plant, where up to 5,000 tons
of CO2 per year are captured and stored in a basaltic
reservoir.

One main stumbling block facing the new approach is the water
required — about 25 tons for every ton of CO2, but the team said
in many places seawater could be used.

Overall, storing CO2 as carbonate minerals significantly
enhances storage security which should improve public acceptance of
carbon capture and storage as a climate change mitigation
technology, it said. Enditem

(Xinhua)