Life-cycle Greenhouse Gas Analysis of Conventional Oil and Gas Development in the Uinta Basin
- Evaluate life-cycle greenhouse gas emissions from several oil sands and shale processes and compare these to conventional liquid-fuel production processes
- Evaluate opportunities to reduce life-cycle CO2 emissions from these unconventional resources such as the use of oxygen firing in upgrading and refining processes for CO2 capture
- Develop modules for predicting life-cycle CO2 emissions with Los Alamos National Laboratory's CLEAR model from conventional oil and gas development in Utah's Uintah Basin for purposes of model validation and uncertainty quantification
Department of Energy, National Energy Technology Laboratory
In the future, one important selection criterion for the nation's energy supply will likely be the life-cycle carbon footprint of the resource. The state of California has already adopted a carbon-based fuel standard, and similar standards are currently being discussed in several states. This project is evaluating life-cycle greenhouse gas emissions (GHG) from several oil sands and shale processes and opportunities for reducing GHG emissions. This project is also developing modules in Los Alamos National Laboratory's CLEARuff model for predicting life-cycle CO2 emissions from conventional oil and gas development in Utah's Uintah Basin in conjunction with two other Institute for Clean and Secure Energy projects, Development of Conventional Oil and Gas Production Modules for CLEARuff and V/UQ Analysis of Basin Scale CLEARuff Assessment Tool.
Available data on life-cycle GHG emissions from a variety of conventional oil and gas, oil sands and shale liquid-fuel production processes are being gathered and summarized. It can be challenging to compare life-cycle estimates of GHG emissions from the production of transportation fuels because of differences in the functional unit (i.e., barrel of raw bitumen, barrel of synthetic crude, energy content), which processes are included in the assessment, (i.e., construction of the upgrading plant, transportation between the upgrading and refining facility, reclamation processes, etc.), and lack of detail on assumptions, conversion factors, and fuel quality. Figure 1 provides a comparison of life-cycle, well-to-pump GHG emissions from gasoline, oil sands, and oil shale processes. A summary of published ranges is listed above each column. For oil shale in general, estimates vary more widely (38 - 180 g CO2 equiv/MJ) than for liquid fuels produced from petroleum or from oil sands because oil shale is not produced commercially in the U.S. and because there is uncertainty over the amount of CO2 released from minerals in the oil shale during processing.
Figure 1: Life-cycle, well-to-pump GHG emissions from gasoline, oil sands, and oil shale processes.
Because of concern over GHG emissions, carbon-based fuel standards and the larger GHG life-cycle emissions of unconventional fossil fuels when compared to conventional fuels, there is significant interest in reducing GHG emissions from unconventional fuel sources through efficiency improvements and carbon capture and sequestration. The refining industry, as the third largest stationary source of GHG emissions globally, is evaluating technologies such as oxy-firing for GHG reduction. Oxy-firing is a promising technology for reducing the CO2 footprint from this industrial sector, but it requires a significant amount of energy to generate oxygen in an air separation unit. An evaluation of the potential for reducing life-cycle GHG emissions from a refinery employing oxy-fuel combustion for CO2 capture in its boilers and process heaters has recently been completed. This evaluation includes the additional GHG emissions associated with the power required for air separation and CO2 handling; the fuel savings from oxy-firing compared to air firing; and the upstream GHG emissions associated with the additional fuel requirements.