Return Carbon to the Ground

Carbon Capture and Disposal

Coal gasification with carbon capture and disposal (CCD) technologies are essential if continued use of coal is to be reconciled with preventing dangerous global warming. Long-term geologic disposal of CO₂ (for thousands of years) is viable now and must be implemented quickly if we are to meet the challenge of sharply reducing global emissions this century. ₁

These technologies could prevent 100 billion tons of CO₂ from escaping coal plants in the next 50 years. Well established but in limited use, CO₂ capture and disposal technology involves capturing nearly pure CO₂, compressing it to liquid form, and injecting it into deep, porous rock formations beneath impermeable cap rock. Such geological formations are common throughout the world at varying depths.

The Intergovernmental Panel on Climate Change has concluded that CCD is viable. In most cases, the CO₂ is gradually (over thousands to tens of thousands of years) absorbed by the surrounding rock, where it mineralizes into solid form. It is possible, however, for stored CO₂ to leak up through well bores and other deep fissures, so accurate siting of injection wells and monitoring of CO₂ floods and disposal are essential.

As a result, ensuring that CCD results in the permanent sequestration needed for climate protection will require rigorous criteria and performance standards for CO₂ injection and disposal sites.

CO₂ and Enhanced Oil Recovery

Coal gasification and carbon capture and disposal are more costly than conventional coal plants. But this cost can potentially be offset by producing additional oil from already developed fields using carbon dioxide captured from coal-fired power plants.

When CO₂ is injected at high pressure into mature oil fields, it pressurizes the well and mixes with the oil, increasing the oil’s mobility and promoting enhanced oil recovery (EOR). The oil is displaced by the CO₂, which can be safely stored in the geologic formations that held the oil.

And although some CO₂ is pumped out along with the oil, this CO₂ can be recaptured and re-injected for additional oil recovery or permanent disposal.

Standard primary and secondary oil production without EOR only recovers about one-third of the original oil in typical reservoirs. Current state-of-the-art EOR techniques generally allow an additional 10 percent of the original oil in place to be recovered.

In fact, 35 million tons of CO₂ are currently used each year to recover 75 million barrels of oil. Unfortunately, most of this CO₂ is pumped out of natural reservoirs rather than captured from industrial sources.

The U.S. Department of Energy estimates that if CO₂ were widely available for EOR, current techniques could recover more than 60 billion barrels of oil from domestic fields in the lower 48 states. ₂

Advanced techniques have the potential to double the amount of recoverable oil to upwards of 120 billion barrels—more than 18 times the amount of oil that is estimated to be economically recoverable from the Arctic National Wildlife Refuge. ₃ At $40 a barrel, these domestic reserves would be worth between $2.4 and $4.8 trillion.

1. For more detail, see the IPCC Special Report, “Carbon Dioxide Capture and Storage.”
2. Six Basin-Oriented CO2-EOR Assessments Examine Strategies for Increasing Domestic Oil Production
3. See NRDC: Issues: Arctic National Wildlife Refuge.