HARTFORD, Conn. (AP) New England's electricity grid operator says natural gas pipeline bottlenecks and retirement of aging power plants could put pressure on the price of energy.

But Gordon van Welie, president and chief executive officer of ISO-New England, said Wednesday that the region has benefited from transmission system upgrades since 2002.

He said at the grid operator's annual briefing to the media that a mild winter and falling oil prices have so far helped push down energy prices. But winter has eight weeks to go and energy use and prices could spike.

Power plants are increasingly relying on natural gas, boosting demand that has led to pipeline bottlenecks, which have led to price increases.