With many Rhode Islanders already facing a difficult winter paying heating bills, electricity provider National Grid has proposed raising rates by about 5.2 percent as of Jan. 1.

The company said that the increase is needed because the price of crude oil has risen dramatically, forcing the company to make extra payments to the generators that supply electricity to its customers through 2008.

The company has proposed adjusting several components of its rates, the biggest of which is an increase in the standard offer rate that represents the actual cost of the electricity itself. The distribution component of the bill will remain unchanged.

National Grid has proposed increasing the standard offer rate to 9.2 cents per kilowatt hour, from the current rate of 8.3 cents per kilowatt hour. The company also wants to make a minor increase in the transmission adjustment charge, and a minor decrease in the transition charge. The net effect of all the changes is a $3.80 increase in the monthly bill of a typical customer, who uses 500 kilowatt hours of electricity a month.

The new monthly bill would rise to $76.66 a month, from its current $72.86 a month.

The company submitted its request late Friday afternoon to the Public Utilities Commission.

The proposal comes at a time when Rhode Islanders are paying record prices for energy. Yesterday, the average price of home heating oil set a record again, rising 6 cents a gallon to $3.209 a gallon, according to the State Office of Energy Resources. It was the 12th consecutive week that heating oil prices have risen.

Regulators have little discretion when it comes to rate increase requests that are based on rising fuel prices. State and federal laws allow utility companies to recover from customers what is paid for electricity or natural gas, as long as the companies make “prudent” buying decisions. The PUC could cut the proposed rate increase, or delay it. But eventually, customers will have to pick up the increased costs.

National Grid has about 476,000 electricity customers and supplies power to the residents and businesses in 38 of the state’s 39 municipalities. The company acts as a buying agent for a vast majority of its customers, purchasing electricity on their behalf through long-term contracts.

Most of those contracts contain clauses that automatically increase the company’s cost of purchasing electricity if the market prices of natural gas and fuel oil rise beyond a certain trigger point.

Those costs are then passed on to customers. The company makes no profit from buying electricity on behalf of its customers. It makes money from distributing electricity to those customers.

The company based its cost projections on natural-gas and crude-oil futures prices on Oct. 25, 26 and 29.

If the company does not increase its rates, it said, payments from customers would fall short of the cost of electricity by $64.7 million by the end of December 2008.

Even with this increase, National Grid said its retail cost of electricity is lower than that of other utilities, including its sister company, National Grid — Massachusetts Electric. The standard offer rate for that company was 10.919 cents per kilowatt hour. The rate for Western Massachusetts Electric was 10.184 cents and Fitchburg Gas & Electric was charging 10.838 cents per kilowatt hour, according to National Grid.

The reason those prices are different is partly explained by the different methods that Rhode Island and Massachusetts use to set rates, said Michael J. Hager, National Grid’s principal analyst for its transmission rate administration and billing department.

Massachusetts’ rates are determined by the average of the price of electricity at two particular times of the year — in mid-September and mid-February, Hager said. Utility companies are required to acquire six-month contracts at those two times, and the rate is the average price of the two, he said.

In Rhode Island, National Grid has contracts with its suppliers that run through 2009 and the base rates have already been negotiated. But the company has to make extra “fuel index” payments if the price of natural gas or crude oil rises above a certain amount.

tbarmann@projo.com