Why we can’t plug Southern California’s massive methane leak
There’s a burgeoning environmental disaster playing out in Southern California — but unlike the widespread media coverage on the Deepwater Horizon, this leak has been invisible until quite recently. In late October, the Southern California Gas Company detected an underground methane leak spewing an estimated 110,000 lbs of gas per hour into Aliso Canyon. Since it discovered the problem, the company has evacuated an estimated 1,700 people and closed two schools.
The leak is normally invisible, but an infrared video taken by the Environmental Defense Fund captured the massive leak and the methane escaping from it at multiple points.
Several of the problems associated with a leak this size are purely practical. The methane reeks of rotting eggs, because we add a chemical called tert-Butylthiol to the normally odorless gas to make certain people can smell a leak.
Reeking like an unventilated football stadium on $1 steak and free draft beer night ought to be punishment enough for anyone in one lifetime, but methane is also explosive, an asphyxiant, and a potent greenhouse gas.
CO2 vs. methane
Most of the conversation around greenhouse gas emissions revolves around carbon dioxide, or CO2. According to the EPA, CO2 emissions account for about 82% of anthropogenic (human-caused) climate change. Methane, in contrast, only accounts for about 10% of total warming. Pound-for-pound, methane is about 21x more potent than CO2 over a 100-year cycle, and as much as 72x more potent within shorter timeframes.
The potency discrepancy reflects the different environmental persistence between the two gases. Methane persists in the environment for 10-12 years after it’s released, but ultimately reacts with water vapor in the upper atmosphere and is converted into carbon dioxide and water. The fact that methane still takes a decade or more to dissipate out of the atmosphere, however, means that a massive leak like this one is still capable of having an impact for a significant period of time.
Current estimate of the total gas leak is around 800,000 metric tons. That’s enough methane gas to boost California’s estimated methane emissions by 25% for the year — and bear in mind, this leak is thought to have begun on October 23.
Why can’t we plug the leak?
There’s another parallel between the Deepwater Horizon leak and the current methane problem in Aliso Canyon — in both cases, the depth and ferocity of the leak made it extremely difficult to plug. In this case, the methane is pouring out of a massive underground containment facility more than 8,000 feet below the surface. Traditional methods of sealing the broken pipe have already failed, so SoCalGas has drilled a second well to intersect the broken pipe.
Once the new well intersects the old one, fluid and eventually concrete will be injected to seal the pipe, rather than attempting to perform the injections at the surface. As of this past weekend, the drillers had located the broken pipe responsible for the leak. That’s no small feat, considering that the second well must be drilled far enough away to prevent any risk of explosion, and the broken line is just seven inches in diameter.