After one of the many attempts to plug the methane-leaking well at the Aliso Canyon natural gas storage facility in the Los Angeles suburbs, the thing erupted like a geyser, spewing not only natural gas, but also the muddy slurry that company technicians had pumped into the well. It reminded me of a phenomenon that disrupted small-town life in southwest Colorado in the 1990s, during a coalbed methane boom. An abandoned natural gas well, drilled decades earlier, would periodically erupt, shooting natural gas, water and debris some 200 feet into the air. Locals dubbed it Old Faithful.
Aliso Canyon is a bit like a gigantic, catastrophic version of the geyser gas well of yore. Since the leak was first noticed, in late October, some 4.6 billion cubic feet of natural gas have leaked into the atmosphere. Most of that is methane, a particularly potent greenhouse gas, along with smaller amounts of other compounds such as benzene, a known carcinogen, and mercaptan, a sulfur compound added as an odorant to the gas. The mercaptan, especially, has been hellish for nearby residents of Porter Ranch, and as many as 3,000 residents have evacuated.
Celebrity pollution activist Erin Brockovich and others have equated the Aliso Canyon leak to the BP oil spill, on land. Indeed, in infrared images, the methane plume does look like thick crude billowing into the sea. But the BP spill was a rare occurrence, while massive methane leaks are horribly common, happening in America's oil and gas fields every day.
The aforementioned Old Faithful was in the San Juan Basin of Colorado and New Mexico, one of the most productive natural gas fields in the nation. Locals were more amused than alarmed by the gas geyser, even though it was within spitting distance of an old folks' home. (Watching the earth projectile vomit was more entertaining than another Lawrence Welk re-run, apparently). People around here had bigger things to worry about back then. Dangerous levels of methane were showing up in crawlspaces and drinking water wells, with occasionally disastrous results, and vast swaths of vegetation were dying off due to methane displacing oxygen. Meanwhile, far more methane - and all those other nasties that accompany it in natural gas - were seeping out of the vast oil and gas infrastructure that is woven throughout the landscape.
Aliso Canyon's leakage rate has averaged just under 1,000 metric tons per day (a rate which slows over time as pressure on the reservoir is relieved). That qualifies it as the largest point-source methane emitter in the nation, leaking at about twice the rate of the Walter Energy coal mine in Alabama, which tops the Environmental Protection Agency's greenhouse gas inventory.
But add up all the oil- and gas-related methane point sources in one hydrocarbon-producing basin and the story changes. San Juan Basin oil and gas facilities emitted 291,162 metric tons of methane during 2014, according to the EPA inventory. But the inventory doesn't account for smaller producers, geologic seeps that have been exacerbated by oil and gas development, abandoned wells or undetected leaks. So actual emissions from oil and gas facilities far exceed the EPA's greenhouse gas inventory, as numerous studies have shown. Take all that into account, and the San Juan Basin's total oil and gas emissions rate is probably closer to 500,000 metric tons per year, or 1,400 tons per day, a far higher rate than at Aliso Canyon.
The same sort of leakage is occurring in other hydrocarbon-producing basins, as well, from the Permian to the Piceance, impacting both the climate and the folks who live nearby. As atmospheric scientist Gabrielle Petron told me last spring: "Your air is being impacted. You live on the edge of the gas field."
Which is not to say that the Aliso Canyon leak isn't a big deal. It is. And a similar catastrophe could happen elsewhere, and probably already is, on a smaller scale. The Aliso Canyon storage facility is a huge, depleted oil field that enables Southern California Gas Company to store natural gas, much of it from the San Juan Basin and other gas fields in the Interior West, and then withdraw it when needed. Another 415 or so of these underground facilities are scattered across the country. Some are in depleted oil and gas reservoirs, others in aquifers or salt caverns, and many are on the edge of urban or suburban areas. With a storage capacity of 86 billion cubic feet, Aliso Canyon is among the largest, but a depleted field near Baker, Montana, can store up to 164 billion cubic feet of gas.
Major incidents, at least ones that directly impact nearby populations, at underground storage facilities have been few and far between. When they do happen, though, they tend to be spectacular. In 2004, ignited gas spewing from a failed valve in Moss Bluff, Texas, created a 1,000-foot column of flames, and in 2001, explosions resulting from gas migrating from an underground storage reservoir in Kansas killed two. Surely many more climate-damaging methane leaks go unnoticed. In depleted oil fields, old wells (the bad one at Aliso Canyon was drilled in 1953) are prone to fail. Meanwhile, a 2013 study published in the Hydrogeology Journal found that in aquifer storage units "gas loss is a possibility via … faults, inadequate caprock seals, or improperly completed wells."
These facilities fall in a regulatory gray area. The Federal Energy Regulatory Commission has jurisdiction over units that are used for interstate commerce, but the agency regulates rates and storage levels, not operations or safety. Others, like Aliso Canyon, are regulated by respective states, often inadequately. (The lack of a safety valve on the leaky Aliso well apparently did not violate California rules, for example.)
New federal rules on oil and gas industry emissions from the EPA and the Bureau of Land Management may help the situation in the gas fields, but the rules will apply to few, if any, underground storage facilities. Colorado regulates oil and gas industry emissions, but not facilities "downstream" from processing plants, like underground storage. A pipeline safety bill introduced in Congress late last year would create minimum safety standards for all underground storage, but its chances of passing are limited.
As long as it is left unfettered, methane leakage, be it on a catastrophic Aliso Canyon-level or the everyday emissions from the gas fields, will continue to sully natural gas's image as a climate-friendly fossil fuel. Still, it may take a while to catch up with coal, at least over the long term. The Aliso Canyon well is emitting methane at a rate equivalent to 32,000 metric tons of carbon dioxide each day*. The Navajo Generating Station in northern Arizona, meanwhile, spews carbon dioxide at a rate of 47,000 metric tons per day. That's like the climate's version of the BP oil spill, and it's happening round-the-clock, with no end in sight.