DOE, EPA Launch Coordinated Carbon Sequestration Project

 

Fossil Energy Techline - 5/01/07

The U.S. Department of Energy (DOE) and the U.S. Environmental Protection Agency (EPA) have begun a coordinated research effort to evaluate how the storage of CO2, a greenhouse gas, might affect the nation's valuable groundwater resources.

The 3-year effort, which will be led by DOE's Lawrence Berkeley National Laboratory (LBNL), is an integral part of the Energy Department's Carbon Sequestration Program. The program is designed to develop technologies to reduce greenhouse gases that contribute to climate change. The coordinated effort by DOE and EPA will take a major step forward in meeting the goals of the program and the overall mission of the President's Global Climate Change Initiative.

"We want to ensure that future CO2 storage is safe, free of harmful environmental affects, and secure for hundreds and thousands of years," said Tom Shope, Acting Assistant Secretary for Fossil Energy. "Making significant greenhouse gas reductions over the long term will require capturing and storing millions of tons. This early coordinated effort between DOE and EPA will take a hard look at CO2 storage in geologic formations so that we can ultimately be sure the nation's drinking water will not be adversely affected by large-scale sequestration."

DOE and EPA will each focus on different tasks related to geologic storage of CO2 and its potential impact on groundwater. While the Energy Department, in general, will focus on large-scale injection of CO2 into deep saline formations and the potential for water displacement into shallow groundwater systems, EPA will concentrate on the migration of CO2 and its possible impact on underground sources of drinking water.

As carbon sequestration technologies are implemented on a larger scale, scientists expect that the amount of CO2 injected and sequestered underground will be extremely large as well. Research efforts to date, however, have not evaluated what impact large-scale injection and related water displacement may have on the groundwater resources in various regions of the country.

DOE is funding LBNL to conduct a series of four research tasks to better understand whether the large-scale increase of water pressure in CO2 storage formations may change the hydrologic conditions in shallow aquifers. This effort will specifically focus on any changes in groundwater table levels, effects on discharge and recharge zones in the groundwater systems, and potential impacts of those changes on underground sources of drinking water.

In the initial phase of the project, LBNL has set up a simulation model for CO2 injection into a deep saline reservoir, far below drinking water supplies, and conducted studies to determine the sensitivity of water displacement and pressure buildup on a variety of saline reservoir parameters. A literature review has also begun to evaluate the potential range of geologic and hydrologic systems considered for CO2 sequestration in the United States.

Also through LBNL, EPA tasks will focus on the potential impact of CO2 migrating from the target geologic formations into shallow aquifers. Little research to date has been conducted on the possible water quality changes that may occur in the groundwater in response to CO2 intrusion.

LBNL will conduct a hydrochemical analysis and modeling studies to assess and better understand the various ways that the migration of CO2 could impact underground sources of drinking water. Data from the studies would provide sound scientific information to both regulators and the public at-large.

To date in the project, LBNL has already set up a reactive-transport simulation model to examine CO2 intrusion into a shallow aquifer and has conducted initial sensitivity studies involving geochemical system behavior and related mineralogy. In addition, LBNL has begun a data search evaluating the geochemical conditions in prominent reservoirs near geologic sequestration sites. The continued modeling and database research will provide a systematic evaluation of main aquifer types in the United States and their potential geochemical vulnerability in case of CO2 intrusion.

This coordinated effort, like most sequestration projects, targets the capture and permanent storage of CO2 from sources such as power plants in various regions of the country. As such, DOE's regional carbon sequestration partnerships, an organization of seven regional partners formed in 2002, may subsequently play an important role in identifying areas of concern in their respective regions. The overall project is being managed by the Office of Fossil Energy's National Energy Technology Laboratory.