As if record-high gasoline prices weren’t bad enough, it appears that electricity and natural-gas rates in Rhode Island are about to spike.

The most recent forecasts submitted by National Grid to state regulators show that the amount of money the utility company collects from customers under current rates is falling short of the actual cost of the electricity and natural gas.

Since the company is allowed to pass on those extra costs to customers, it expects to file rate increases for both natural gas and electricity in the next few weeks.

“There’s nothing to indicate that the size of the undercollections that are projected for the electric side … and the gas side will improve,” said David Graves, spokesman for National Grid.

He said the size of the rate increases the company will request is still unclear, but it expects to file the increases by the end of the month. That means the earliest that rates could increase is July 1.

National Grid is Rhode Island’s dominant utility company, providing service to 245,000 natural-gas customers and 477,000 electricity customers.

Energy prices have been surging over the past three months. On Monday, the average price of regular self-serve gasoline in Rhode Island set another record. The price was $3.739, up 13 cents from last week, and up 74 cents over the past 14 weeks.

The price of crude oil and natural gas have a direct impact on the cost of electricity because National Grid’s contracts with its suppliers call for the company to make extra “fuel index” payments if the price of natural gas or crude oil rises above a certain amount. The company does not make any money on the charges for electricity or gas, but makes its profit on the delivery of that energy.

Last month, National Grid told the Rhode Island Public Utilities Commission that rates were not bringing in enough to keep up with the increase in energy prices.

On the electricity side, the company estimated that by the end of this year, revenues from customers would fall short of actual electricity costs by $43.4 million.

A back-of-the-envelope calculation shows the minimum rate increase needed to make up this undercollection. National Grid delivers 6.6 billion kilowatt-hours of electricity each year. Rates would have to increase about 7/10 of 1 cent per kilowatt-hour to raise an extra $43.4 million, according to calculations by The Journal. That amounts to a monthly rate increase for a typical customer using 500 kilowatt-hours of electricity of $3.50 a month.

But the rate increase request is likely to be higher because that forecast was made using prices of crude oil and natural-gas futures from March 25, 26 and 27. At that point, natural-gas prices were up 21 percent since the beginning of the year. As of May 6, the price was up 42 percent for the year. And crude-oil futures had been up about 5.3 percent in late March. As of May 6, they were up 22.3 percent.

On the natural-gas side, National Grid is projecting an undercollection through October 2008 of $9.4 million. That calculation was made using a futures price as of April 16. Natural-gas futures have risen about 7 percent since then.

tbarmann@projo.com