Greenhouse gas emissions
Overall, the benefits of natural gas in reducing greenhouse gas emissions are clear. Natural gas is the cleanest-burning fossil fuel, and emits up to 60 percent less CO2 than coal when used for electricity.
For this reason, the abundant supplies of natural gas produced by XTO Energy and others has contributed to a reduction in U.S. carbon-dioxide emissions to levels not seen since the 1990s as electric utilities have switched from coal to natural gas for power generation. Remarkably, the country has achieved these environmental gains even as the economy has grown by 60 percent. The abundant supplies of natural gas coming from America’s shale fields have positioned the U.S. to be a net exporter of natural gas, which can mean lower emissions worldwide.
XTO Energy manages methane emissions as a matter of safety and environmental responsibility. Responsible methane containment practices are applied during drilling, completion and production operations to minimize methane emissions. We manage emissions through a mix of voluntary and regulatory actions, such as implementing leak detection and repair programs, reducing oil and gas completion emissions and targeting replacement of high-bleed pneumatics with lower-emitting devices.
After drilling and completion of a new well, our workers prepare the production equipment for decades of operation. A key part of these preparations is to ensure that the natural gas product is contained by the production equipment. In several areas where XTO operates, we utilize optical gas imaging cameras to locate equipment leaks that would otherwise be invisible, which allows us to detect leaks and make repairs.
There is a growing interest within the scientific and policy communities on human-related methane emissions. In the United States, we are working with federal and state governments and within industry to ensure that regulations aimed at reducing emissions of methane and volatile organic compounds sufficiently support long-term operations, achieve emission reduction objectives and provide flexibility for technology.
We continue to seek greater understanding of the magnitude and characteristics of oil and gas industry-related methane emissions. XTO participated in studies conducted by the University of Texas and Environmental Defense Fund which quantified the methane leakage rate in the United States from Upstream gas production activities at 0.4 percent of the total gas produced. The results of this study helped validate Environmental Protection Agency estimates. We are active in ongoing methane research including participating in a methane measurement reconciliation study with the Department of Energy’s National Renewable Energy Laboratory to close the knowledge gap between methane measured at ground sources and methane measured from the air. We are also working with Stanford University on its new Natural Gas Initiative, which will focus on methane measurement and monitoring technologies.
Local / Ambient air
Unconventional resources development operations require the use of over the road and non-road mobile machinery and stationary machinery that result in local or ambient air emissions. Heavy mobile equipment is required to construct the well pad, many truckloads may be required to provide water for drilling and hydraulic fracturing as well as to remove waste water, and engines burning diesel or natural gas are typically required to power the drilling rig and hydraulic fracturing operations. Compressor stations, necessary to transfer gas to interstate trunk lines for sales, also can require large natural gas fueled engines that power compressors.
XTO addresses these localized air emissions in a variety of ways. Initially, federal standards for mobile engines must be met through a given state’s vehicle emissions testing program, or manufacturer certification of emissions. Where stationary equipment is proposed to be installed, an evaluation of air permit requirements is conducted and any required federal, state or local air permits are obtained before operations begin. These permits typically contain limits for various air pollutants that are based on government air standards derived from health criteria. Permit conditions and control requirements vary based on specific stationary equipment, site emission totals, location, and state rules specific to the oil and gas industry sector.