A gas flare is a controlled flame at an oil or gas facility that burns off excess natural gas, a byproduct of petroleum production. You’ve likely seen one from a distance: a tall metal stack with a bright flame shooting from its tip, visible day and night near refineries, drilling sites, and chemical plants. Flaring exists primarily because capturing and transporting that gas isn’t always economically practical, so operators burn it instead of releasing it raw into the atmosphere.
Why Oil and Gas Sites Flare Gas
Every operating oil well produces variable amounts of what the industry calls “associated gas,” a raw mixture of highly volatile hydrocarbons, mostly methane. This gas comes up alongside the oil whether operators want it or not. When a site lacks the pipeline infrastructure to move that gas to market, or when processing it would cost more than it’s worth, the gas gets routed to a flare and burned.
Flaring also serves a critical safety function. Chemical plants and refineries maintain flare systems to relieve emergency pressure buildups. If equipment malfunctions, cooling systems fail, or an entire unit needs to depressurize quickly, large volumes of flammable gas must go somewhere. Releasing it unburned would create an explosion risk, so flaring converts it to less dangerous combustion products. In that sense, the flare is a last line of defense against catastrophic failure.
How a Flare System Works
A flare system is more than just an open flame on a pipe. Several components work together to make the process safer and more efficient.
- Knock-out drum: Before gas reaches the flame, it passes through a large drum that separates out any liquids. These liquid hydrocarbons burn unpredictably and can produce heavy smoke, so removing them first improves combustion. For emergency systems, this drum is sized for worst-case scenarios like a total unit depressurization.
- Liquid seal: A water-filled seal sits between the gas header and the flare stack. It prevents flame from traveling backward into the piping system, a dangerous scenario called flashback. It also acts as a shock absorber against any explosive pressure wave.
- Purge gas: A small, continuous flow of gas is fed into the stack between the water seal and the tip. This keeps oxygen from creeping back down into the system, which could create an explosive mixture inside the piping.
- Pilot flame: A small, always-on flame at the tip of the stack ensures the waste gas ignites the moment it exits. Without a reliable pilot, gas can escape unburned.
- Flare tip: The nozzle at the top of the stack where combustion happens. Its design controls how gas mixes with air, affecting flame stability and how cleanly the gas burns.
Most flares at refineries and chemical plants are elevated, mounted on tall stacks that keep the flame well above ground level and away from workers. Ground-level flares, enclosed in short structures, are sometimes used at sites where noise and light need to be minimized, though they handle smaller gas volumes.
What Flaring Releases Into the Air
When a flare burns efficiently, it converts methane and other hydrocarbons into carbon dioxide and water vapor. That’s the ideal scenario. The reality is messier. Flaring also releases black carbon (soot), nitrogen oxides, sulfur dioxide, carbon monoxide, and various volatile organic compounds depending on the gas composition and how well the flame is performing.
The industry has long assumed flares destroy 98% of methane. Airborne measurements published in the journal Science tell a different story. Researchers sampled flares across three major U.S. gas-producing regions and found that flares effectively destroy only about 91% of methane. The gap comes from two problems: some flares burn inefficiently, and others go out entirely without anyone noticing. That 7-percentage-point difference translates to methane emissions five times higher than official estimates, accounting for 4 to 10% of total U.S. oil and gas methane emissions. Since methane traps far more heat than carbon dioxide over short timescales, those unburned releases carry outsized climate impact.
Health Effects Near Flaring Sites
Communities living near flaring activity face measurable health consequences. The pollutants released, particularly fine particulate matter, nitrogen dioxide, and ground-level ozone, contribute to respiratory disease, heart disease, and stroke. Research in the Eagle Ford Shale region of Texas found an association between flaring activity and increased risk of preterm birth. In North Dakota, flaring was linked to more respiratory-related hospital visits.
A comprehensive U.S. study estimated that emissions from flaring and venting cause over $7.4 billion in annual health damages, roughly 710 premature deaths per year, and about 73,000 childhood asthma flare-ups. Those numbers also include 92 childhood asthma emergency department visits and 10 asthma hospitalizations annually, all attributable to the air quality impacts of flaring operations.
Global Flaring by the Numbers
Global gas flaring hit 148 billion cubic meters in 2023, a 7% increase over the previous year and the highest level since 2019. To put that in perspective, 148 billion cubic meters of natural gas could power tens of millions of homes for a year. Instead, it was burned with no energy captured.
The top nine flaring countries account for 75% of all gas flared worldwide but produce only 46% of global oil. That imbalance reflects how flaring concentrates in regions where gas infrastructure lags behind oil production, whether due to geography, economics, or regulatory gaps.
Efforts to Reduce Flaring
The World Bank launched its Zero Routine Flaring by 2030 initiative in 2015, aiming to end the practice of routinely burning off associated gas during normal oil production. (Emergency and safety flaring would still be permitted.) As of 2024, 57 oil companies and dozens of governments have endorsed the initiative, including major players like ExxonMobil, Shell, Saudi Aramco, and Occidental. The total number of commitments stands at 108.
On the technology side, flare gas recovery systems capture gas that would otherwise be burned and reroute it for productive use, either as fuel for onsite power generation or compressed for reinjection into the well. These systems use specialized compressors designed to handle the wet, variable-composition gas typical of flaring streams. They’re one of the most straightforward ways to turn a waste stream into a resource, though the economics depend heavily on local gas prices and the cost of connecting to pipeline infrastructure.
Despite these commitments and technologies, global flaring volumes continued to rise in 2023, suggesting that progress remains uneven. Routine flaring persists in regions where capturing gas is technically possible but not yet economically or politically prioritized.