Technologies like CarbonCure introduce recycled CO2 into fresh concrete, capturing it and reducing net carbon emissions during manufacturing. Photo credit: Vertical River
As communities close to home and around the globe experience increasingly severe and frequent weather impacts, climate change is top of mind for individuals and countries alike. One of the greatest culprits in a warming Earth is the increase in the amount of carbon dioxide in the atmosphere. But scientists are working on technological and biological solutions to cool the atmosphere by extracting and trapping carbon from the air.
The Paris Agreement
Ratified in 2015 by 185 countries to date, the Paris Agreement is an international treaty to mobilize and unify a global response to current and future climate change. Treaty members pledge to limit this century’s global temperature increase to “well below” 2 degrees Celsius (or 3.6 degrees Fahrenheit) above pre-industrial levels1, implementing green energy sources and significantly reducing greenhouse gas emissions that contribute to climate change. The agreement also establishes resources to assist developing countries committed to addressing climate change.
Greenhouse gas emissions and carbon sequestration
Greenhouse gas emissions contain billions of metric tons of carbon dioxide (CO2). This CO2 has been accumulating in the global atmosphere for the 150 years humans have been burning fossil fuels.2 Excessive greenhouse gases trap heat and lead to unnatural environmental warming.
To remove substantial amounts of carbon from the atmosphere, emissions-reduction solutions are necessary. Capturing and securely storing carbon that would otherwise remain in the atmosphere is known as carbon sequestration, and today scientists worldwide are exploring the most effective ways to achieve it. Approaches to carbon sequestration fall into two broad categories:
Technological carbon capture
According to the U.S. Environmental Protection Agency (EPA), more than 40 percent of the nation’s CO2 emissions come from two sources: electric power plants that burn fossil fuels like coal and natural gas, and industry facilities that process ethanol and natural gas. The EPA estimates that currently available carbon sequestration technologies can reduce these CO2 emissions by 80 to 90 percent.4
Carbon sequestration technologies capture, concentrate and trap CO2 that would normally be released into the air. The CO2 can be trapped in material like concrete or plastic or injected into rock formations deep in the earth. Burying CO2 in the ocean is another avenue of exploration.
A joint project by Archer Daniels Midland Co. (ADM) and the U.S. Department of Energy is one successful example of the trap-and-bury approach. Carbon is a byproduct of processing corn into fuel-grade ethanol at ADM’s plant in Decatur, Illinois. ADM constructed a carbon compression and storage facility and began sequestration in 2017. The carbon is injected into the Mount Simon Sandstone, a saline reservoir stretching across portions of the Midwest. The site’s geological conditions have made it ideal for sequestration. No significant impacts on the integrity of the reservoir or on underground drinking water sources have been reported. As of March 2018, the project had permanently and safely stored roughly 640,000 metric tons of carbon dioxide.5
Other technological approaches will, in time, improve the separation, transport and storage of carbon dioxide and could economically convert recovered CO2 into benign materials that have commercial value.
Low-tech biological solutions
Trees have the potential to extract CO2 from the air and store it in in leaves, roots, bark and wood; forests worldwide currently sequester millions of tons of CO2 each year. Efforts to plant trees in new places and replant deforested acres could increase this amount.6
In addition, farmland, grassland, peatland and coastal vegetation can remove CO2 from the air and store it. Plants found along the coasts and in tidal salt marshes rival forests in sequestering CO2. That makes restoring coastal vegetation and extending coastal habitats a viable solution that will also help protect coastlines from erosion as temperature increases cause sea level rise.7
Ocean plants absorb large amounts of CO2. Their ability to absorb more is only limited by the availability of nutrients needed for them to grow and multiply. Researchers are exploring strategies for fertilizing the ocean to increase plants’ ability to extract and store carbon.8
Biochar—the charcoal produced from burning plant matter such as logging or crop waste—is another option. This slow-to-decompose charcoal can be buried or spread on farmland to sequester carbon.9 When injected with nutrients, biochar can also serve as a long-lasting organic fertilizer.
Impact of the built environment
The built environment can incorporate both technical and biological solutions for carbon sequestration. Specifying the use of concrete and plastic materials injected with CO2 in new and remodeled buildings is an opportunity for designers and builders to have a positive impact on reducing atmospheric carbon, as are green roofs and green infrastructure. In addition, using carbon-rich wood for construction will extend trees’ carbon storage capacity beyond the forests.10
These and other solutions to address carbon sequestration and climate change can be found in the 2017 book, Drawdown: The Most Comprehensive Plan Ever Proposed to Reverse Global Warming, by environmentalist, entrepreneur, journalist and author Paul Hawken. He and his work with the organization he founded, Project Drawdown, were honored with the 2019 Argon Award at Southface Institute’s Visionary Dinner on September 19.
Sources:
1: https://unfccc.int/process-and-meetings/the-paris-agreement/the-paris-agreement
2,3: https://www.ecowatch.com/carbon-sequestration-2461971411.html
4: https://archive.epa.gov/epa/climatechange/carbon-dioxide-capture-and-sequestration-overview.html
5: https://www.aiche.org/conferences/aiche-annual-meeting/2018/proceeding/paper/329c-successful-demonstration-illinois-industrial-carbon-capture-and-storage-saline-reservoir
6, 7, 8, 9, 10: https://www.ecowatch.com/carbon-sequestration-2461971411.html
