Real-World Assessment Shows Outsized Benefits of Shrouds on Reducing Emissions from Low-Flow Utility Oil and Gas Flares in North American Oil and Gas Basin

Flares in the oil and gas industry are assumed to achieve methane destruction efficiency of 98%; however, recent studies reveal significantly lower efficiencies and higher-than-expected methane emissions from some flares. This study combines real-world operating parameters and wind data on actual flares in North Dakota with new experimental measurements of utility flare performance to quantify the effects of wind on methane emissions from these low-flow flares. The results show that wind speeds of 4.5–6.7 m/s (10–15 MPH) reduce the average methane destruction efficiency to 96.4%, doubling methane emissions from low-flow flares relative to current assumptions. Retrofitting utility flares with shrouds can increase efficiencies to ≥98%, reducing methane emissions by half, potentially avoiding on the order of 0.204 million metric tons of carbon dioxide equivalent emissions per year, and highlighting an inexpensive methane mitigation opportunity. The results also indicate that methane source estimates and aerial measurements likely undercount low-flow (≤0.033 m3/s or ≤100 thousand standard cubic feet per day, MSCFD) flares, missing an important source of methane emissions.