Environment & Science

Cold weather strains local gas supply

File photo of a weather vane.
File photo of a weather vane.
Stock photo by Garry Knight via Flickr Creative Commons

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As overnight temperatures drop and demand for natural gas for home heating rises, Southern California Gas Company is stretching its supply this week by reducing the fuel it provides to local power-generating utilities.

Monday night, SoCal Gas notified the Los Angeles Department of Water and Power and the California Independent System Operator that it was reducing supplies of natural gas beginning Tuesday morning. The reduction to power producers continues at least through Friday, SoCalGas spokesman Chris Gilbride said.

Other big users of natural gas like hospitals, factories and refineries that are considered "non-core customers" are on a "curtailment watch," which means their supply of gas could be reduced if a more serious shortage develops.

Cutting back on gas deliveries to utilities that have local gas-fired power plants spares the supply needed by SoCal Gas' "core customers" of households and small businesses. Cutting the supply of gas to homes and small businesses is the last thing the utility would want to do because it is very labor-intensive work to restore gas service to so many customers.

Los Angeles Department of Water and Power has received only about 40 percent less gas than it would normally get, said Reiko Kerr, a senior assistant general manager. The DWP can import electricity from coal and gas-burning plants outside the L.A. Basin. It can also lean more heavily on wind and solar power if those sources are available. The utility also has gravity-fed hydroelectric generators that use water at Castaic Lake. The last time SoCal Gas reduced deliveries of gas to power producers was in August, Kerr said.
For other power providers like Southern California Edison and smaller city utilities – the California Independent System Operator acts as a manager, said ISO spokesman Steven Greenlee. ISO notified its member utilities on Monday they’d have to get along with a lesser amount of gas this week. If it were to be cut off entirely – ISO can route power from out of the area to different parts of our region, he said.

The return of the Aliso Canyon gas storage field to active use has been challenged by some environmental groups who want the region  to be less dependent on fossil fuels. It is also opposed by some Porter Ranch area residents who consider the field unsafe and say it causes continuing health problems.

Alexandra Nagy of the environmental group Food & Water Watch called on the California Public Utilities Commission Thursday to investigate the circumstances that led to the reduction of gas deliveries and the need to withdraw gas from Aliso Canyon. SoCal Gas  for some time had three of its pipelines out of service at the same time, reducing gas deliveries to Southern California. One of those pipelines is now back online, Gilbride said.

Before withdrawing gas from the Aliso Canyon gas field, SoCal Gas followed procedures imposed by the California Public Utilities Commission, said PUC spokesman Christopher Chow. Those procedures included first withdrawing gas from the company's other gas fields.
The gas supply issues are one more energy reliability issue left over from the Aliso Canyon gas well blowout in late 2015.   Before that, the vast underground reservoir at Aliso Canyon stored up to 86 billion cubic feet of gas, building up supplies over the summer when gas was cheap, and withdrawing it in the winter when the price was higher.

The gas field supplies that extra hit of gas when there isn't enough in the local pipelines to meet spikes in demand.

But the disastrous failure of one of the Aliso wells, resulting in the nation's largest ever uncontrolled release of gas, caused the company to  shut down and overhaul other wells at the gas field.  Even after the repair and updating of 53 of the company's 114 gas wells, the company is limited by state regulators as to how much it is permitted to store underground. The field can now hold only about one-third of its previous volume.

So now, the region is more dependent on just the gas that’s in the distribution pipelines, plus what’s in three much smaller gas storage fields, and a small amount that can be withdrawn in times of threatened shortages from Aliso Canyon.