The problem could be alleviated somewhat if technology improvements were made to the natural-gas delivery system, said Questar analyst Darren Shepherd. However, he said, those upgrades would be costly and would require significant investment from private natural-gas fuel providers.

"We are getting some calls from retail stations, and we've got a team of folks taking a look at our infrastructure and other options," Shepherd said. "We are hoping that we see the private sector step it up a little bit."

The improvements to the stations' tanks would cost hundreds of thousands of dollars per location. He said that before such an expensive endeavor would move forward, the supply of natural-gas vehicles would have to increase sufficiently to warrant it.

Despite the pressure issues, drivers are typically willing to wait to pay about 86 cents per gallon of natural gas, compared with more than $4 per gallon for gasoline.

Jones said the demand for natural gas for vehicles has increased more than 220 percent in the past year. He said the main reason is the popularity of natural-gas vehicles in the current environment of record-high gasoline prices.

Knight said that he has noticed an increase in the number of dual-fuel vehicles on the road, which utilize gasoline and natural gas. The dual-fuel or bi-fuel vehicles run on natural gas until that tank is empty, then switch to run on gasoline.

That technological convenience is what prompted the company that Doug Nielsen works for to purchase a used bi-fuel pickup truck for $10,000 about two months ago. He now pays around $12 to fill the natural-gas tank, compared with $120 for the gasoline tank.

Nielsen said the company would likely recoup its investment in about one year, based on the fuel cost savings. He estimated that the company saves $100 per day on fuel.

According to Questar, more than 100 Utah businesses and government agencies operate some 3,500 natural-gas vehicles. Questar itself has more than 560 natural-gas vehicles, which account for 62 percent of its fleet.

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