CEDAR FALLS - While writing up his lesson plans for a course at the University of Northern Iowa, Lee Potter pictured a day when operating a gasoline-powered engine is merely a hobby.

His students might not take up restoring and operating the gasoline-powered engine, but Potter said college students of today will make significant decisions about what energy source would best replace petroleum.

"At some point it will become more cost effective to find another energy source," Potter said.

The geologist won't say when that point will occur, but in his class, students learn that analysts predict world oil production will peak this decade, if it hasn't already.

When will it peak?

Regardless of whether the peak will happen, this decade people need to start thinking about it, Potter said.

Jennifer Moehlmann, an energy analyst with the Iowa Department of Natural Resources said there are differing opinions on when oil production will fail to meet demand.

The most optimistic estimates say the peak won't occur until 2050.

"Some say it actually already occurred. It's a hard thing to pin down," Moehlmann said.

"We are just dragged along by the current," Moehlmann said. "The best thing we have is our refineries that produce ethanol."

Iowans can reduce their demand for gasoline by keeping their engines tuned up, taking less road trips and buying fuel-efficient vehicles, she said.

"Not everyone needs to buy a Toyota Prius but they could buy the more fuel efficient SUV," Moehlmann said.

Gasoline prices are expected to hit highs this week. But those higher prices are due to requirements that sulfur be removed from gasoline for cleaner emissions, Moehlmann said.

The Organization of Petroleum Exporting Countries, OPEC, has announced a cutback in production which will have an effect on prices as well.

But with the impending peak, price volatility is here to stay, Moehlmann said.

"We are continuing to demand and use more and supply isn't keeping up," she said, "That's why energy efficiency is such an important concept."

Conserving energy could delay the peak, but it won't stop it from happening.

Other energy sources have their drawbacks.

Wind and solar energy do not provide steady supplies. It takes oil and coal to produce hydrogen. Ethanol can replace a portion of gasoline. Mixtures with as much as 85 percent ethanol are available in Iowa. But it takes products of oil and natural gas to fertilize fields and power tractors. Crude oil also finds its way into several other products, including plastics.

What oil is left

Thomas Ahlbrandt, world energy project chief of the United States Geological Survey, said there are about 1.1 trillion barrels of known conventional oil reserves and the USGS estimates another 1 trillion barrels would be discovered through new sites or increasing reserve estimates.

In 2005 the world is expected to consume 30 billion barrels of oil, according to a study performed by the U.S. Department of Energy.

If demand remained constant, the world would have used that 1.1 trillion barrels of known reserves in 30 to 35 years. Some say the shortage is already here.

John Groves, a UNI professor who spent 15 years in the oil industry, won't venture a guess as to how much oil is left and how much could be found.

When he started working in the industry, oil companies could drill offshore in water only hundreds of feet deep. Today offshore rigs operate in depths up to 7,000 feet.

Alternatives should be found to oil if only to gain independence from oil in the Middle East, he said.

Saudi Arabia is home to the largest oil reserves. Iraq, with 112 billion barrels of estimated oil reserves, is second in line.

How will we know?

When the peak does occur, UNI earth science professor Lynn Brant predicted controversy will brew over whether the peak has arrived. Oil producers may claim they have plenty of oil.

"When the peak happens there will be a real price increase in fuel," Brant said.

In the 1950s gas went for 25 cents a gallon. Today if that rate were adjusted for inflation alone the price would be about $2 a gallon, he said.

The average rate in the United States is about $1.73 for regular unleaded, according to www.aaa.com. But prices in some larger U.S. cities have topped $2 a gallon.

With increases, people will conserve energy in ways that wouldn't make sense today, Brant said.

"They will seriously consider on cutting back on usage, like we saw in the '70s," during the Arab oil embargo and energy crisis then, he said.

Potter and tells college students that they will see the peak in their lifetime and have to deal with finding petroleum replacements.

"The bottom line is if we are not at the peak, I think it's near. Once we cross over, market forces will drive us to something else," Potter said.