Over time, the carbon dioxide seeps into the producing well, creating a mixture of oil, natural gas, and carbon dioxide. If the energy content is sufficiently high, the gaseous portion of this mix will probably be sent to a gas plant. However, if the energy content is low, the gas is likely to be vented or flared. At this time, there is no basis for the EIA to estimate the quantity of added carbon dioxide that is vented or flared. However, the annual amount of carbon dioxide used for enhanced oil recovery is probably on the order of 12 million metric tons.
Emissions are, therefore, some fraction of that figure.
Lead Smelting Smelting of lead includes a stage in which limestone undergoes calcination. Emissions estimates cannot be calculated for this report because there are no known statistics regarding the amount of limestone used in lead smelting. The EIA is currently researching alternative data sources in an effort to include estimates of these emissions in future reports. Waste Treatment and Incineration Wastewater treatment produces methane emissions when the organic content is decomposed anaerobically. According to the IPCC, developed countries such as the United States typically use aerobic treatments, reducing the potential for methane emissions.