Cyndi Loza

Gasoline prices, which had held steady recently, soared unexpectedly this week — shooting up 20 to 40 cents in some parts of Illinois. Experts blame the price increase on recent shutdowns at Midwest refineries, among other factors.

The increase in gas prices varies across the state, AAA spokeswoman Nicole Niemi said Wednesday. But Chicagoans might be hit with the 40-cent price spike, said Dave Sykuta, executive director of Illinois Petroleum Council.

Prices for regular grade gas Wednesay ranged from $2.99 in northwest suburban Lake in the Hills to $3.59 on Chicago’s South Side.

One Midwest refinery that has suffered recent production problems is the BP refinery in Whiting, Ind. After it shut down a 235,000-barrel-a-day processing unit, the Chicago area’s supply of gas suffered, Sykuta said.

He said the refinery is among about 10 facilities that produce the reformulated gas that the Clean Air Act mandates for the city in the summer.

When the Whiting BP refinery goes down, it’s hard for other refineries to make up for the shortfall, Sykuta said.

The Indiana BP refinery is the second largest in the United States and the biggest in the Midwest. A source at the refinery said Wednesday that the unit that has been shut down should be up and running by the end of the week and reach normal productivity by next week.

Some experts think more refineries should be built to meet the demand for gasoline. Laurie Hopkins Falter, spokeswoman for the Energy Information Administration, said no new refineries have been built in the United States for more than 30 years.

Some drivers, like the ones pumping gas at the BP station at Dearborn and Congress in the South Loop, aren’t happy about gas price increases.

“I think it’s too high. I think there’s a lot of people that are saying the same thing,” said Armando Barba, 41, of Little Village.