Gasoline prices could rise by 20 cents per gallon in the next few weeks, and higher fuel prices will affect a lot more than just the cost of driving.

With crude oil north of $90 a barrel and heading for $100, consumers likely will be paying more for electricity, air travel and any goods arriving in the Islands by boat or plane.

But it's gasoline prices where the spike will be seen first, and that could leave families with tough choices.

"Higher gas prices will ... drain discretionary income from consumers (unless they drive less and/or borrow more) and thus reduce consumer spending on nonfuel items," Jack Suyderhoud, a University of Hawai'i-Manoa economics professor, said in an e-mail.

Yesterday, the average price of regular unleaded gasoline in Honolulu was $3.22 a gallon, according to AAA. Prices were $3.32 a gallon in Hilo and $3.65 in Wailuku, AAA said.

Nationally, prices are expected to rise as they catch up to the recent spike in crude oil prices, which last week threatened to break $100 a barrel. (A barrel equals 42 gallons.)

The only possible relief is that gas prices are volatile and could go down just as quickly as they've risen, said Leroy Laney, Hawai'i Pacific University professor of economics and finance.

Nevertheless, motorists are resigned to higher prices and say they'll find ways to drive less.

Shirley Alexander, a Waimanalo resident, said she's going to be more conscious when she drives.

"It's a lot higher now than the last time I filled up," Alexander said. "I've thought about carpooling, but my hours aren't regular."

Others filling up yesterday at Lex Brodie's on Queen Street, where regular was $3.269, greeted their gas tabs with a philosophical shrug of their shoulders.

"I'm not really gonna change anything," Glenn Omalza said. "Everything is going up. There's nothing I can do about it."

TIGHTER BUDGETS

Typically, Hawai'i drivers pay among the highest gasoline prices in the nation. Those prices are caused by the state's isolated, small market, which isn't subject to the same fluctuations in supply and demand that force Mainland prices to move.

The impact on residents' spending power has been increasing. According to a report released Monday by the Oil Price Information Service, Honolulu residents spend about 2.37 percent of their median household income on gasoline per month per vehicle.

That's lower than the national figure, or 3.8 percent, but it's up significantly from 2002, when Honolulu residents were paying 1.47 percent.

As families spend more on gasoline, they have less for everything else.

"Our budgets will be more constrained," said Laney, of HPU. "The more you pay out for gas at the pump and for energy means less money for other things."

Two areas that are registering an effect are electric bills and shipping.

Yesterday, Matson Navigation Co., the state's largest cargo shipper, said it will increase its fuel surcharge by five percentage points to 29 percent on Dec. 14.

Fuel price increases have boosted the average electric bill by 16 percent from November 2006 to this November, said Darren Pai, a spokesman for Hawaiian Electric Co.

In any given month, the average O'ahu electricity bill can go up or down based largely on fuel costs. For example, bills in January decreased by $9.42, mostly because fuel costs decreased. But in July, fuel costs drove up the average bill by $11.82.

Retail prices also will be affected.

"We're held hostage by our remoteness," said Carol Pregill, president of the Retail Merchants of Hawai'i. "From the consumer's point of view, it's a double whammy: the increase of gas and the increase of the cost of goods."

OPTIONS AVAILABLE

There are ways to cope.

Savvy shoppers can go online and seek out the cheapest gasoline stations in the neighborhood.

There's also carpooling.

Every time gas goes up, more people call looking for a way to rideshare, said Vicki Harris, executive director of Vanpool Hawai'i.

Statewide, more than 250 vehicles are available for vanpooling as many as seven passengers. Five years ago, there were 130 vanpools in use, Harris said.

"The need and the want is consistent with the rise in gas prices," Harris said. "We have a concentration of calls from 'Ewa and Central O'ahu."

In the end, Island residents are particularly captive to rising prices.

"People will talk about the price of gas, but there's not much choice," said Bill Green, former Kahala Shell dealer and consultant. "It's still emotional. People will think (twice) about driving, but they'll still drive and spend $2 on gas to buy a 50-cent item."

Reach Suzanne Roig at sroig@honoluluadvertiser.com.