Benchmark intends to undertake the development work for a CO2 injection project at the Raeford North Carolina plant including evaluation of the saline aquifer suitability, injection well permitting requirements, incremental air emissions, and DOE co-funding investigation.
Benchmark participated in the pre-development of an ethanol project in Aurora North Carolina (approximately 180 miles from Raeford) where CO2 sequestration was determined feasible to be injected unto the underground saline aquifer. We anticipate the geological conditions in Raeford (Coastal Plain) to be comparable to the conditions in Aurora. The important nature of the CO2 injection project would make it a suitable candidate for implementation in a second phase, after the initial commissioning of the Raeford ethanol production operations.
Preliminary Assessment of North Carolina Saline Aquifer Suitability:
Analysis and site characterization were performed in 2006 during the development of the Agri Ethanol Project in North Carolina to determine the feasibility of injecting CO2 in the saline aquifer for long term storage, based on available geological data.
Some of the work performed included:
• Seismic surveys to define the subsurface geological structure and identify features that
could create leakage pathways in the subsurface.
• Formation pressure measurements, if available, to map the rate and direction of
groundwater flow.
• Water quality samples to demonstrate the isolation between deep and shallow
groundwater.
• Geological site description data from wellbores and outcrops to characterize the storage
formation and seal properties.
The project results were obtained in coordination with:
• United States Department of Energy (USDOE) Carbon Sequestration Regional Partnership Programs, in particular the Southeast Carbon Sequestration Partnership, which includes North Carolina (SECARB)
• United States Geological Survey (USGS)
• North Carolina Geological Survey
The analysis identified two potential subsurface zones that have good potential for CO2 sequestration.
These sites are throughout the Coastal Plain in North Carolina at depths greater than 1,500 feet, that contain saline groundwater and are far below the base of the underground sources of drinking water (USDW). These units contain sand zones with thickness of at least 20 feet and the sand zones are underlain and overlain by clay zones with thickness of at least 20 feet. These provide permanent containment and trapping the injected CO2.
If underground drilling proves difficult at the Raeford property, the study did identify an injection site in Sanford North Carolina (50 miles away). This location has sediment-filled Triassic-age rift basins which make it suitable for CO2 Geo sequestration.
Raeford may require a deeper (more costly) drilling to reach the saline aquifer. However, geological CO2 storage is generally considered to be more effective at depths greater than 2,500 feet, where ambient pressures and temperatures can result in CO2 being in a supercritical fluid state. The density of CO2 fluid will range from 50 to 80 percent of density of the saline groundwater under these conditions.
Conclusions:
Based on the Aurora project analysis and review of the geological characteristics in North Carolina, there is the potential in Raeford for permanent containment of CO2 with sufficient storage capacity in sand zones with sufficient thickness, porosity, lateral extent and hydrologically isolated from fresh waters aquifers.
For additional information, please contact the Company
