Typically, longer-term contracts are at fixed prices, while spot purchases can be enormously volatile.

"I had a couple of years to go on my old contract but I was more than happy to agree a new, longer-term contract," he said.

Mr. Polan said the city hoped to offer longer-term contracts eventually.

The utility buys much of its gas supplies on the spot market, where until recently prices were lower than in longer-term contracts.

Or do they go for a longer-term contract?

And the direct deliveries develop relationships that lead to longer-term contracts, executives said.

Reggie Evans, who turned down a longer-term contract with Seattle over the summer, averaged 23.8 minutes last season.

"Probably, given the chances of the revenues flattening out in the next two years, I'd take a chance on a longer-term contract."

The automakers were principally concerned with negotiating a longer-term contract.

The sector benefits from having longer-term contracts to the extent that there is a foreseeable volume of work in many cases.