Natural Gas Pipeline Replacement Programs Reduce Systemwide Emissions
Since 1990, pipeline replacement has reduced emissions from the natural gas pipeline system by more than 12 million metric tons of CO2e, the equivalent of removing over 88 million passenger cars from the road for one year.
For more than three decades, natural gas utilities have implemented pipeline replacement programs to retire legacy distribution pipes, particularly those made of cast iron, wrought iron, or unprotected steel, and replace them with modern materials. Mains removed through these programs have typically been substituted with cathodically protected steel and, increasingly, plastic pipelines, that are more efficient and durable. This record can be traced to gas utilities continuing to prioritize safety and systematically upgrading infrastructure through risk-based integrity management programs. These long-term investments in pipeline replacement and modernization have significantly reduced pipeline emissions, strengthened system reliability and resiliency, and modernized distribution networks as the natural gas system continues to expand and serve new customers.
Key Findings:
- Between 1990 and 2024, pipeline replacement contributed to a reduction in emissions from the natural gas pipeline system of more than 12 million metric tons of CO2-equivalent, (CO2e) the same as removing over 88 million passenger cars from the road for one year, or approximately 260,000 cars every year for 34 years.
- Since 1990, the share of plastic main pipeline mileage has increased from 27 percent to 63 percent in 2024, while protected steel has decreased from 53 percent to 34 percent. Cast iron and unprotected steel together have declined from roughly 20 percent of all mains to less than 3 percent of total main mileage over the same period.
- As pipeline materials have been replaced, the system has continued to expand. The total mileage of mains increased from approximately 874 thousand miles in 1990 to 1.3 million miles in 2024, a 58 percent increase.
- Despite this growth, methane emissions from distribution mains have declined sharply, falling from 16.4 million metric tons (MMTe) in 1990 to an estimated 3.2 MMTe in 2024, an 81 percent decrease.
- Emissions intensity per mile of main pipeline has fallen nearly 90 percent over the last three decades. By material type, emissions per mile of pipe decreased by 78 percent for cast iron, 64 percent for unprotected steel, and 92 percent for plastic, reflecting the ongoing impact of replacement programs, improved leak detection technology, and enhanced system integrity management.
Methodology Note: Methane emissions for 2023 and 2024 were estimated using a log-linear regression applied separately to each pipeline material type. All regression slopes were statistically significant (p < 0.0001). Annual emissions totals for 2023 and 2024 were calculated by summing the extrapolated emissions values across all material categories for each year.
AGA Contact: Lauren Scott, 202-824-7152 Brendan O’Brien, 202-824-7220.
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