Scientists have found that buried natural gas pipelines in the Sacramento region likely leak a significant amount of methane. A major component of the natural gas that is transported from transmission lines to the pipe networks that deliver the product to homes and businesses, methane is a potent greenhouse gas that can cause significant damage to the environment. While the amount that is leaking is believed to be relatively small, researchers say the gas could still cause problems, as methane is as much as 25 times stronger than carbon dioxide, making it increasingly effective at trapping heat in the atmosphere.
Stanford University published a study in the February issue of the journal Science, revealing that 200 previous studies on pipeline methane emissions underestimated leakage rates. Moreover, because the Environmental Protection Agency had not seriously analyzed the issue since 1996, emission rates were 75% higher than the EPA had originally projected. Given that the Sacramento area has 7,100 miles of natural gas pipelines belonging to the Pacific Gas and Electric Co., even with relatively small leakage rates, any increase beyond the original estimates could have serious impacts on the region.
While global warming is a serious issue, methane pollution poses a number of additional problems for the Sacramento Valley: because methane reacts with nitrogen dioxide in the atmosphere to form ozone, high methane rates can cause an overproduction of the gas. High levels of ozone in urban areas have been linked to respiratory problems and other diseases, and the Sacramento area has exceeded healthy ozone standards every year since 2008. Accordingly, the California Air Resources Board recently found that measurements of methane in the Central Valley were 70% higher than expected. As a result, the agency is considering methane regulations for oil and gas production, processing and storage.
These recent statistics only add to growing evidence of pipeline leakage: in 2011, the United States Pipeline and Hazardous Materials Safety Administration, an agency within the Department of Transportation, found around 30,000 in the state of California. In 2012, they identified another 54,278 leaks. That same year, the ARB reported that 94,170 metric tons were being emitted into the atmosphere. While a number of industries other than natural gas also produce methane, including rice and dairy farming, oil and gas drilling and production are decidedly a significant source of the problem.
Currently, California is lagging behind states like Colorado and Wyoming when it comes to dealing with pipeline methane emissions. This is likely related to the fact that California, unlike other areas, does not require gas companies to find and repair leaks. While stronger standards were set for utility companies to fix leaks that pose a danger to the public after the San Bruno PG&E explosion in 2010, the state still does not require companies to fix natural gas leaks that do not pose a risk of fire or explosion. They are also not required to report leaks they discover that have not been scheduled for repair.
In response to the reports of increased leakage rates, the Environmental Defense Fund is assisting 90 universities with studies relating to methane emissions, as well as partnering with utility companies to research the extent of the problem. Likewise, the EPA has stated that the agency is placing further emphasis on the problem and will release a response by fall. Meanwhile, a bill currently being considered in the state Legislature would require numerous state bodies, including the ARB and the California Public Utilities Commission, to adopt rules and procedures for minimizing leaks and emissions.