The maximum amount natural gas that can be flowed to users from the aging Cook Inlet gas fields has been steadily declining over the years, and in a cold snap last January gas demand came close to the limit. The maximum deliverability has declined further since then, and a shortfall is more likely if the severely cold weather of early 2009 recurs.
Most of the electricity generated in Southcentral comes from power plants that burn natural gas. If regionwide demand exceeds gas supply, the amount of gas flowing to power stations would be reduced rather than affecting the gas supplies used for heating homes and businesses.
As a result, Southcentral likely would experience rolling electricity blackouts across the region.
At a recent meeting of the Regulatory Commission of Alaska, the state agency that regulates the utilities, Chugach Electric Association and the other Railbelt utilities described their draft plan for what to do in a shortage.
The draft said the utilities would initiate steps to reduce their gas needs, while issuing consumer alerts to request voluntary reductions in gas demand. The concept is to try to keep electricity flowing by engineering a "soft landing" for the gas supply system, said Bradley Evans, chief executive of Chugach, an Anchorage power company that serves much of Southcentral.
If a gas shortfall appears imminent, the measures power companies would initiate could chop their gas demand by up to 40 percent, Evans said. Those measures could include:
• Maximizing the output from hydroelectric power plants such as Bradley Lake on the Kenai Peninsula.
• Buying power from the Fairbanks electric company.
• Moving the power load between different power generation units.
• Asking Seward to switch to its backup diesel power generation plant.
• Purchasing additional emergency gas supplies from gas producers.
• Possibly reducing gas consumption through emergency adjustments to the "spinning reserves" that power plants must be kept in hand.
RED ALERT
Beyond this, electricity and gas consumers would get alerts asking them to reduce their own demand.
There likely will be three alert levels: green, yellow and red, said Phil Steyer, Chugach's director of government relations.
Green would signify normal operations, albeit with requests to use energy wisely.
Yellow would flag caution, requesting the initial lowering of thermostats and minimizing or ceasing the use of some types of electrical or gas appliances.
Red would indicate an emergency and consumers likely would be asked to lower thermostats more and take other actions such as turning off water heating.
The utilities plan to meet in advance with government entities to determine how energy demand might be reduced in public buildings during cold, dark winter evenings, if needed.
"That would be a preplanned response we envisage from those (public) organizations that have a lot of square footage," Steyer said.
20-MINUTE BROWNOUTS
The utilities anticipate that the alerts could prompt a 15 percent voluntary reduction in gas demand. Added to the 40 percent demand reduction potentially achieved by the power companies, the utilities would have additional interruption wiggle room above the 25 percent of gas usage required to keep essential systems such as the power transmission network running.
"It's very similar to Enstar (the main Southcentral gas utility) wanting to keep the pipeline system up," Evans said. "If the transmission system were to be taken down, then we don't have the emergency purchases coming from Golden Valley (the Fairbanks electric company). We don't have access to all of the hydro."
The possibility that Anchorage's city-owned utility Municipal Light and Power, which serves part of town, could switch to its backup diesel generation, and that might provide a little additional flexibility in determining minimum gas supply levels, he added.
ML&P General Manager James Posey told the commissioners that his company tries to keep a three- to four-day supply of diesel on hand. After that, ML&P would need additional diesel -- roughly one truckload every two hours, he said.
If power cuts do become necessary, these would most likely occur in the evenings, when gas demand is at its highest, and would likely be limited to 20 minutes, recognizing that most gas-fueled furnaces need electricity to run, Evans said.
The utilities plan to roll out a community education plan by around Sept. 18 and complete an Anchorage emergency action plan by Oct. 23.
They want to do a trial run of voluntary energy curtailment in October to see how much gas consumption might be cut.
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