US natural gas pipelines vulnerable to electric outages

A team of researchers at Carnegie Mellon University has investigated the vulnerability of electric power generation to electric outages at US pipeline compressor stations and suggested actions that could prevent potential hazards. 

Natural gas supplies 32 per cent of all primary energy in the United States. Although the cross-country natural gas pipeline system used to be powered mainly by natural gas, it has recently switched in places to electric power.

This reliance on electricity has made the pipeline system more vulnerable during hurricanes and other times of high electric load. This led in one 2021 event in Texas to the deaths of over 200 people, according to the researchers.

Compressor stations typically have enough backup power on site for auxiliary demands, but electrically driven compressors are usually too large for practical on-site backup. Therefore, an electric outage could take on-site electric compressor units out of service.

To prevent this, Carnegie Mellon researchers have mapped the vulnerabilities of gas pipelines and recommended steps to be taken to prevent gas shortages.

“The North American Electric Reliability Corporation has stated that addressing gas-electric interdependency risks is a top priority that requires immediate attention,” said Sean Smillie, who led the research. “But due in part to the lack of regulatory oversight of the gas transmission system and the extent of reliance on electric compressors, the potential consequences of failure are not well understood.”

The researchers have conducted what they called the "first rigorous effort to identify the number of US electric compressor stations".

To do so, they examined data from 2008 to 2020, finding nearly 1,500 stations or substations. Of these, they determined that approximately 10 per cent are electric, with several large pipelines vulnerable to electric outages.

California, the Midwest, the Gulf Coast, and the East have high levels of installed electric compressor capacity. 

"During times of high gas demand, electric outages that disable compressors at these stations can significantly reduce gas available to downstream generating stations," explained Professor M Granger Morgan, who co-authored the study. "In some cases, the resulting outages could be as large as or larger than the most severe single-cause failure currently considered in electric reliability planning."

Based on their findings, the authors suggest that electric utilities should immediately incorporate the identified facilities into critical facility lists.

"In contrast to well-established reliability reporting and standards for the electrical system, the gas system has almost no reliability transparency or oversight," said Professor Jay Apt, who co-authored the article. "Establishing a federal gas reliability organisation, comparable to what is now done for electric power, could improve gas reliability by establishing appropriate reliability reporting, incident investigation, and minimum industry standards." 

The researchers' findings and recommendations were published in the Electricity Journal.