SoCalGas' Aliso Canyon Leak a Disaster For Climate

Those of us Californians who have gone to a lot of trouble to reduce our climate change footprint ought to be mighty peeved at the Southern California Gas Company right now: that corporation has just undone a huge amount of our hard work, significantly raising the state's emissions of a dangerous greenhouse gas.

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According to the California Air Resources Board, a leak that started October 23 at a SoCalGas well in the Aliso Canyon area near Porter Ranch has accounted for a quarter of all the methane released by the state since the leak started, with estimates of up to 50 metric tons of the potent greenhouse gas leaking into the atmosphere each hour since the leak started.

Methane is a far more potent greenhouse gas than carbon dioxide. So far, the leak may have spewed enough methane into the atmosphere to equal the greenhouse gas output of burning just under a billion pounds of coal -- and SoCalGas says it may be several more months before it is able to stop the leak.

Assuming that upper-hand estimate of 50 metric tons of gas per hour is correct, that would be about 37,000 metric tons of methane leaked from SoCalGas's well since October 23, from what is apparently a cracked 11-inch well casing somewhere a few hundred feet below the surface of the earth.

Calculating methane's greenhouse gas potency as compared to carbon dioxide isn't straightforward, as the gas breaks down over time into water, CO₂, and other compounds. That breakdown takes a while. A commonly used comparison says that methane has 21 times the greenhouse gas potential of CO₂, but that figure averages out that methane's impact on climate over 100 years after it's released, as much of the methane breaks down. Methane's short-term warming effect in the atmosphere is even greater: when you measure using a timeframe of 20 years, the gas is 56 times as potent a greenhouse gas as CO₂.

Using the 100-year figure by way of EPA's methane emissions reduction calculator, the 37,000 or so metric tons of methane released so far by SoCalGas -- about 41,000 standard American tons -- will have the same greenhouse gas effects as if we released more than 929,000 metric tons of carbon dioxide into the atmosphere.

That's a lot of greenhouse gas. It's equivalent to the annual emissions from more than 195,000 passenger cars. That's the kind of figure that gets tossed around a lot in climate discussions, so let's make it more personal.

In September 2014, California passed an important threshold: since then, more than 100,000 plug-in electric cars are being driven in the state. Electric vehicles aren't carbon-neutral yet: around two-thirds of the electricity sold in California comes from burning fossil fuels. Comparing the greenhouse gas outputs of electric and gas-powered vehicles isn't easy, but we can say this much: SoCalGas just wiped out several years' worth of climate gains made by Californian electric car buyers.

You can make similar comparisons for the climate actions made by Californians who shelled out for rooftop solar panels, who decided to forego trips by air and stayed home, or who spent money to weatherize their homes. Some of us spent significant amounts to reduce our climate footprints, only to see a huge chunk of those overall gains wiped out by one gas well owned by one corporation.

That applies to SoCalGas, as well. Southern California Gas's parent corporation, Sempra Energy, also owns San Diego Gas and Electric. SDGE buys power produced by Pattern Energy's Ocotillo Express Wind facility in Imperial County. Sempra and SDGE have boasted of their commitment to lowering greenhouse gas emissions by buying power from Ocotillo Express and other renewable energy facilities.

According to the American Wind Energy Association, using electricity generated by wind turbines reduces emissions over the standard American grid power mix by .6 metric tons of CO₂ for every megawatt-hour of power produced.

Those reductions will be less in California, because California doesn't use as much greenhouse-intensive coal power as do many other parts of the country, and replacing somewhat cleaner power with wind thus means smaller reductions in carbon emissions. But let's use AWEA's figure to provide a generous estimate of how much Ocotillo Express might be reducing California's CO₂ emissions. Ocotillo Express' turbines have a total rated capacity of 265 megawatts. That means that for every hour all of Ocotillo's turbines are producing as much power as they can, according to AWEA's nationwide average, the emissions reductions that result add up to 159 metric tons of CO₂.

159 metric tons is a lot of CO₂. But 929,000 metric tons of CO₂, the equivalent of the methane released so far by Sempra/SoCalGas's leak, is a lot more. Ocotillo Express' turbines would have to produce power at full capacity for 5,842 consecutive hours to offset the greenhouse gas emissions from that leak, and since Ocotillo Express' turbines tend to produce about one fifth of their theoretical maximum power output, that's about three years and four months of typical operations at Ocotillo.

Or look at it the other way around: seeing as Ocotillo Express just started going online three years ago next week, SoCalGas's leak in Aliso Canyon just wiped out all the climate gains its parent company has claimed by buying power from Ocotillo, and more.

That's all given the size of the leak so far. SoCalGas is telling regulators that it could take 90 more days to fix the leak, which at current leakage rates estimated by the state could mean another 100,000 metric tons of methane lost to the atmosphere. The company also says it'll be preparing its own estimate of the size of the leak, which estimates will likely come in significantly lower than the California Air Resources Board's.

Looks like Californians will have to redouble our efforts to reduce our own climate footprints, instead of leaving it up to the energy companies. If SoCalGas takes another 90 days to fix things, the EPA's methane emissions reduction calculator says the greenhouse gas equivalent of the lost methane could be sequestered by 93.4 million trees growing for ten years. That's three trees for every Californian. Personally, I think SoCalGas should pick up the tab.