Methane emissions in Baltimore show seasonal, daily trends
Natural gas leaks are a significant source of methane emissions in cities, but it can be hard to pinpoint exactly where and why they happen. And methane, a potent greenhouse gas that is the main chemical component of natural gas, has been historically undercounted or omitted in emissions estimates, according to a team of atmospheric and climate science researchers in the Penn State College of…
Methane emissions in Baltimore's urban and suburban neighborhoods show both daily and seasonal patterns, a new study has found. Researchers from Penn State College of Earth and Mineral Sciences analyzed readings from seven measuring towers in and around the city, comparing them with local gas usage data from 2022. They discovered that daily gas usage rates and methane emissions mirrored each other, both peaking during the day and dropping at night.
However, these daily fluctuations were not linked to seasonal trends, suggesting that the cause of daily emissions is not related to heating systems or leaks from appliances. Instead, the study proposes that these daily emissions could be due to leaks originating from year-round usage of water heaters and kitchen appliances. On a seasonal level, urban neighborhoods in Baltimore experienced a spike in methane emissions in February, followed by a gradual decline until reaching a low in August.
This pattern correlated with the local gas distribution company's seasonal repair schedule, indicating that the freeze-thaw cycles causing shifts and separations in legacy cast-iron pipes were responsible for the seasonal fluctuations. Suburban and rural areas, on the other hand, showed a flat seasonal pattern due to newer PVC pipes that do not shift as much during temperature changes.
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