Storing Carbon and Stopping Methane Leaks in the Northeast: USGS Options

The U.S. Geological Survey (USGS) is building science support for decision-makers in its North Atlantic–Appalachian Region who want to remove and store carbon and cut greenhouse gas (GHG) emissions. According to the EPA, the region's 14 states and D.C. produced about 18% of the nation's GHG emissions in 2021.

Potential underground CO2 storage areas and industrial CO2 sources in the region. Image from the USGS fact sheet

Storing CO2 underground

Geologic carbon sequestration stores carbon dioxide (CO2) deep underground. CO2 is captured from factories and power plants, or from the air at direct air capture facilities, compressed into a liquid, and injected into porous rock in geologic basins.

In 2013, the USGS assessed onshore areas in the region where CO2 could be stored, and a 2019 study assessed offshore areas nearby. Storage potential lies mainly under southern New York, Pennsylvania, West Virginia and Kentucky, and offshore from Virginia to Massachusetts; industrial CO2 output is highest in western Pennsylvania, West Virginia and Kentucky.

A carbon dioxide injection well. Photograph by Peter Warwick, U.S. Geological Survey

Turning CO2 into rock

CO2 mineralization chemically locks CO2 into a solid mineral, such as a carbonate — a reaction that happens naturally and can be sped up, and that traps CO2 effectively. It works mostly with igneous rocks (especially mafic and ultramafic) and some metamorphic rocks, including asbestos-bearing ones, rather than sedimentary rock. There are two approaches:

• injecting CO2, or CO2 mixed with water, into rock deep underground
• exposing broken rock at the surface — such as mine tailings — to CO2

In the region, candidate mafic and ultramafic rocks run from Maine to Virginia, and asbestos occurs mainly in Vermont and from northern New Jersey to northeastern Virginia. More research is needed to measure how much CO2 each site could hold; U.S. mineralization resources are poorly defined, though globally the potential may be enormous.

Potential areas for CO2 mineralization: mafic and ultramafic rocks and asbestos sites. Image from the USGS fact sheet

Olivine on beaches and marshes

Over geologic time, weathering of certain igneous rocks pulls CO2 from the air. Adding olivine — a mineral in mafic and ultramafic rocks — to beaches and wetlands could harness that: as olivine weathers, it removes CO2 and raises ocean alkalinity, storing the carbon as bicarbonate, which makes up about 85%–90% of seawater alkalinity and stays in the sea for about 100,000 years. It could help fight both ocean acidification and climate change.

The region has more than 2,000 km of coastline and coastal wetlands. Thin layers of such sand, alone or mixed with dredge spoils, might also help wetlands keep pace with sea-level rise — important for the roughly 25% of U.S. wetlands that are degraded and sinking. But effects on wildlife, soils and coastal water chemistry need study first.

USGS and National Park Service scientists core the soil of a salt marsh where olivine was applied. Photograph by U.S. Geological Survey

Plugging leaking wells

Methane (CH4) leaks from abandoned and orphaned oil and gas wells — orphaned wells have no operator left to plug them, and even plugged wells can leak as old seals age. The EPA estimated U.S. abandoned wells emitted 276,000 metric tons of methane in 2020. The 2021 Bipartisan Infrastructure Law funds plugging them.

An orphaned well in Pennsylvania. Photo by Nicholas Gianoutsos, U.S. Geological Survey

Many early wells were never well documented, and a well that can't be found can't be checked or plugged. The USGS has published a preliminary national dataset of unplugged orphaned wells — concentrated here in western New York, western Pennsylvania, West Virginia and Kentucky — and is measuring methane before and after plugging to show the real emission cuts.

Unplugged orphaned oil and gas wells in the region. Image from the USGS fact sheet

An abandoned pump-jack well in Guadalupe Mountains National Park, Texas. Photograph by National Park Service

Coal mine methane

All coal mines release methane; gassy underground mines emit more than 100,000 cubic feet a day. Coal mining and abandoned mines made up about 7% of U.S. methane emissions in 2021. As coal mines close, thousands may leak methane through ground deformation, boreholes and shaft seals. Capturing methane from coal beds and during mining cuts emissions — and unlike other greenhouse gases, methane can be turned into usable energy, possibly creating jobs where mining jobs were lost. The USGS is developing ways to measure emissions at active and abandoned mines.

Active and abandoned coal mines, and abandoned "very gassy" mines, in the region. Image from the USGS fact sheet

The ventilation exhaust fan and methane oxidation unit of an underground coal mine in southwestern Virginia. Photo by Özgen Karacan, U.S. Geological Survey

Sources

Based on Peter D. Warwick, Madalyn S. Blondes, Sean T. Brennan, Steven M. Cahan, C. Özgen Karacan, Kevin D. Kroeger and Matthew D. Merrill, Geologic Carbon Management Options for the North Atlantic-Appalachian Region, U.S. Geological Survey Fact Sheet 2023–3038; a work of the United States government in the public domain.