Shocked, Shocked: "Carbon Capture" Potential 1/10th Of Prior Estimates - There Just Aren't Enough Suitable Sites

Drawing down carbon from the air and stashing it in underground rock formations has been framed as an essential way to slow and reverse global warming. But new research published Wednesday in the journal Nature finds there are far fewer suitable places to do this than previously thought. After screening out “risky” areas, like those that are vulnerable to earthquakes, a team of researchers from Europe and the U.S. found that the Earth can only safely store about 1,460 gigatons of injected carbon in its sedimentary basins. This is an order of magnitude less than previous estimates, and — if you convert stored carbon to an estimated impact on the climate — only enough to cut global warming by about 0.7 degrees Celsius (1.3 degrees Fahrenheit), not the 6 degrees C (10.8 degrees F) described in other research. Carbon storage “can no longer be considered an unlimited solution to bring our climate back to a safe level,” one of the study’s co-authors, Joeri Rogelj, said in a statement. “Geological storage space needs to be thought of as a scarce resource that should be managed responsibly to allow a safe climate future for humanity.” Rogelj is director of research at the Grantham Institute on climate change and the environment at Imperial College London.

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According to the United Nations’ Intergovernmental Panel on Climate Change, or IPCC, the world’s foremost authority on the topic, at least some carbon storage will be necessary to achieve international climate targets. But the amount needed is dependent on a number of factors, including how much countries plan to slash emissions versus “offsetting” them, especially from hard-to-decarbonize sectors, and whether they intend to blow past 1.5 or 2 degrees C (2.7 or 3.5 degrees F) of global warming and then return to a more liveable temperature by removing carbon from the atmosphere. The latter is a contentious idea known as “overshoot,” and it would necessitate more carbon pulled out of the air and stored. Some IPCC scenarios involving substantial overshoot assume up to 2,000 gigatons of carbon storage by the year 2100.

According to the study’s authors, no previous global or regional estimate of the Earth’s technical carbon storage potential has taken into account key risk factors that would make some areas undesirable for storage. Starting from an estimate of all potentially available storage sites, their analysis cuts out areas that are too shallow, too deep, and too prone to earthquakes, as well as environmentally protected areas and areas near where people live. This reduces the total available capacity for carbon storage from 11,780 gigatons to just 1,460 gigatons of CO2, 70 percent of it on land and 30 percent on the seafloor.

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Despite significant hype around the technology, only about 0.05 gigatons of CO2 are currently stored via point-of-emission carbon capture each year. So far, most of these carbon capture projects inject carbon into the ground to aid the extraction of even more oil and gas, in a process known as “enhanced oil recovery.” And only 0.00001 gigatons of CO2 are removed from the ambient air each year. That’s less than the stated annual greenhouse gas emissions of Bowdoin College, a small liberal arts school in Maine.

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https://grist.org/science/carbon-storage-limits-nature-climate-change/