Solving the global warming problem requires both responsive (adaptation) and proactive (carbon capture and storage) solutions. Global energy demand is projected to increase by more than 50 percent in the next 50 years due to rising populations and increased per capita consumption. Indeed, it has been increasing by 2.5 to 3 percent annually since the late 19th century, but unevenly throughout the developed and undeveloped world. Attaining an equivalent standard everywhere would involve tripling per capita energy consumption.
Continued burning of fossil fuels to meet such future energy needs would increase carbon dioxide (CO2) concentrations in the atmosphere to previously unknown levels. And natural sinks — systems such as plants, the ocean, and soil that absorb and store CO2 from the atmosphere — remove only a portion of greenhouse gases.
As future emissions continue to climb, albeit more slowly, there is an urgent need to advance carbon capture and storage solutions to provide ways to “turn back the clock” on emissions to mitigate warming and adverse impacts on coastal infrastructure, biodiversity, food, and water sources. The cost of not addressing this issue is estimated to be nearly 1 to 2 percent of global GDP, amounting to more than $200 billion in annual costs to the U.S. economy alone.
Geological carbon capture and storage strategies were major components of the U.S. and Chinese emissions proposals for the 2015 COP21 Paris Agreement, which called for 30 million tons of CO2 to be stored annually to meet the Agreements’ 2050 emissions targets. But U.S. participation in the international Paris Agreement was unfortunately undone by the Trump administration.
To nurture an effective solution, however, what really matters is the next 20, 30, and 50 years, when we will be driven by our changing environment to find enduring solutions to mitigate climate change. These solutions will ultimately involve capturing and storing a huge volume of CO2 .
Unsurprisingly, conventional land-based underground reservoirs have generated ardent opposition from the affected communities and raised concerns about CO2 leakage and costly monitoring over time. Among many possible solutions, new research efforts are making remarkable proof-of-concept advances in geological storage solutions. This opens the door for safe and permanent storage through the rapid reaction of CO2 and natural volcanic minerals to form safe and solid carbonate (e.g., limestone). Iceland’s CARBFIX project and U.S. Department of Energy programs have demonstrated the rapid mineralization of CO2 through successful field tests and in the laboratory. There exists enormous storage capacity in these rocks worldwide, below the ocean and in remote on-land locations; the geological storage potential far exceeds past and future emissions.
In CARBFIX, a land-based pilot project at the Hellisheidi Power Plant in Iceland, scientists injected 250 tons of CO2 dissolved with water and hydrogen sulfide into basalt 400 to 800 meters underground, and demonstrated rapid conversion of the mixture to mineral form — calcite — within two years.
In fact, 95 percent of the 250 tons of injected CO2 had transformed to solid mineral phases — a rate far faster than the 8 to 12 years originally expected. Basalt rock contains abundant calcium, iron, and magnesium, which react naturally with CO2 to form the solid carbonate minerals. As the project in Iceland has shown, carbon capture and injection in basalt promises safe, permanent storage, effectively turning CO2 gas to solid mineral.
The success in Iceland opens up new opportunities to consider offshore CO2 storage in vast offshore ocean basalt provinces and large land-based basalt provinces in Greenland, the northwestern U.S., Siberia, India, and Morocco. Sub-ocean basalts possess massive storage capacity and naturally convert carbon into mineral form through alteration processes below the ocean. We are now looking to engineer systems that accelerate this natural means of CO2 sequestration, and sub-ocean basalts could offer a safe and permanent carbon storage solution. The offshore avenue also avoids the difficult problems associated with proximity to human activities and private property and has tremendous potential for addressing the global CO2 challenge.
New, scaled up demonstration projects, both offshore and on land, can test whether our approaches will work at large scale and permanently convert CO2 into solid rock. On land, CARBFIX scientists are currently increasing injection amounts up to 15,000 tons of CO2 annually in a deeper basalt reservoir in Iceland.
Offshore, we are undertaking a pre-feasibility study with funding from the U.S. Department of Energy to assess factors required for monitored CO2 deep-sea disposal into basalt off the northwest coast of the U.S. and Canada. With information gathered in the pre-feasibility study, we will move towards a pilot demonstration project with the goal of injecting and monitoring more than 10,000 tons of CO2. This will test CO2 trapping efficiency in the sub-seabed, and with rapid conversion into stable and environmentally benign carbonate minerals formed in the basalt, can permanently sequester the carbon. Success in these projects will demonstrate a dramatic reduction in risks for long-term CO2 disposal at an industrial scale in safe and secure geological reservoirs.
Our immediate focus is to advance viable, scalable solutions that can be deployed in time to be effective. Assuring carbon storage at massive scales is an essential next step toward removing large amounts of CO2 from the atmosphere and safely, permanently storing it, providing a vital solution to maintain our planet’s habitability in the future.
— David Goldberg is a geophysicist and Lamont Research Professor at Columbia University’s Lamont-Doherty Earth Observatory