The Role of Pipeline Compressor Station Modernization in Lowering Emissions

Pipelines are vital to our energy infrastructure. They transport gas that heats our homes and powers the industrial facilities that make products we use daily. Minimizing the environmental impact of this necessity is imperative as the world embraces a more sustainable future. One priority of both the emitters (utility and gas company owner/operators) and regulators (agencies like the Environmental Protection Agency) is to lower emissions from pipeline operations. This priority is shared by hundreds of institutional investors, corporations and public entities working across their supply chains to meet net zero carbon emission goals and keep climate change in check.  

Changes to Emission Standards

To meet this emissions reduction priority, the EPA has clarified regulations for the industry. On Nov. 15, 2021, the EPA proposed a rule to reduce methane emissions from the oil and gas industry that will replace the New Source Performance Standards finalized in August 2020. The 2020 NSPS was disapproved (or treated as though it never took effect) with President Joe Biden’s executive order in January 2021. A final ruling on the EPA's proposal is expected by the end of the year. 

Voluntary methane emissions programs, in partnership with the EPA, have been ongoing for several years and produced significant results. Programs like the EPA Natural Gas STAR program, the Methane Challenge program and ONE Future Coalition, among others, have decreased average methane emissions from transmission and storage natural gas compressor stations 31% from 2011 to 2019, despite the addition of close to 200 facilities during the same period. This reduction is equivalent to removing 1.5 million passenger vehicles from the road in those nine years, according to an Interstate Natural Gas Association of America report in February 2021.  

Both voluntary and compliance-required actions are achieving these results. Most owner/operators of cross-country pipelines are actively addressing emissions through programs like compressor station modernization, focusing on aging pipeline infrastructure where newer technology can significantly lower emissions and increase operational efficiencies. 

Compressor Station Modernization Options 

Gas pipeline routes typically have a compressor station every 50 to 100 miles. Many stations were built decades ago, with the best technology available at the time, but owner/operators are now upgrading or replacing these stations with modern technology. Some of the options our industry experts have seen while working with owner/operator companies in this modernization process include: 

• Replacing gas turbines and engines with electric motor drives. A large portion of compressor stations across the country use natural gas as fuel to drive compressors on their pipeline systems. Owner/operators are evaluating opportunities to replace this equipment with electric motor drives, eliminating natural gas as fuel and lowering overall facility emissions. Electrification is a key pathway towards economy-wide decarbonization. 
• Recovering vapor gas through a process of reinjecting blowdown gas into the pipeline system instead of venting it to the atmosphere. Traditionally, pipeline operators isolate and vent the compressor station piping to the atmosphere for planned maintenance activities (i.e., valve replacements or compressor repairs). New VGR developments not only reduce emissions by decreasing venting, but also capture valuable natural gas that otherwise would have been lost. 
• Installing carbon monoxide catalysts and selective catalytic reduction technology on exhaust system equipment. If you drive a car or a newer model diesel truck, you may be familiar with catalytic converters and exhaust systems using diesel exhaust fluid. A catalytic converter converts toxic gas (i.e., carbon monoxide and hydrocarbons) into carbon dioxide and water. SCR systems in diesel trucks inject a liquid-reductant agent, typically urea, through a special catalyst into the exhaust stream to convert nitrogen oxides into diatomic nitrogen and water. Like the automotive industry, pipeline owner/operators are implementing emissions control technology on exhaust systems at compressor station facilities. Carbon monoxide catalysts serve the same purpose as catalytic converters and SCR technology is implemented (typically with ammonia as the liquid-reductant) on exhaust system equipment to reduce overall emissions.  
• Implementing leak detection and repair programs to better maintain aging seals and valves on equipment, which can leak methane emissions.  

These are just a few examples of efforts to modernize compressor stations and reduce emissions. The industry has focused on secondary containment for various hazardous liquids for decades. Now it’s time to take a similar approach by continuing to develop technologies that contain gaseous emissions. Utility and gas pipeline owner/operators, which have long been working toward sustainable energy, will continue these initiatives with voluntary programs as well as compliance and investor-driven directives.