In the State of the Union address last Tuesday, President George Bush expressed a desire to "take a crucial step and protect our environment in ways that generations before us could not have imagined."

He proposed making all cars hydrogen-powered, and he said the possibility for pollution-free cars is near.

Hydrogen technology is already being explored in depth at the Hydrogen Energy Center at Penn State.

There are two ways to use hydrogen as a fuel source in vehicles, said Dan Haworth, associate professor of mechanical engineering.

First, hydrogen can be burned, in a process similar to that used in combustion engines, he said.

An alternate and more environmentally friendly method involves using hydrogen to generate electricity, which then runs an electric motor, he said.

Haworth said there are "significant advantages" to using hydrogen technology.

However, there is still a lot to be done before this technology finds widespread use in vehicles.

"There's a lot of research to be done," he said.

Hydrogen is a very flammable gas, as well as being less dense --and thus bulkier -- than gasoline, he said.

"Storing it and transporting it is a big issue," he said.

In addition, this technology remains expensive, said Andre Boehman, associate professor of fuel science.

Advocates who tout hydrogen technology as almost perfectly efficient and pollution-free are misled, he said.

"That's missing an important piece of the puzzle: Where did you get the hydrogen?" he said.

Today, the primary source of hydrogen is natural gas, he said.

Using natural gas as a hydrogen source produces significant levels of carbon dioxide, he added.

Also, with technological advances in the automobile industry, gas and diesel cars will have very low emission levels in the future, he said.

"Let's face it. In 2007, we will have ultra-low emission cars. We're talking about very modest levels of emissions," he said.

Researchers at Penn State are working to find other, less polluting sources of hydrogen. Bruce Logan, professor of civil engineering, said they are working on obtaining hydrogen from wastewater with high sugar content.

Through the process of fermentation, researchers would be able to generate hydrogen, he said.

This would greatly reduce damaging carbon dioxide emissions.

While the technology to power cars solely by hydrogen may still be a distant dream, vehicles powered by a blend of natural gas and hydrogen may become more common in the near future, said Bohdan Kulakowski, professor of mechanical engineering.

This type of technology poses far fewer problems.

Though prototypes for completely hydrogen-powered vehicles are already in existence, "there's still a long way to go" with regard to this technology, he said.

But despite the obstacles, it is important for researchers to continue exploring hydrogen technology, said Darryl Farber, associate professor of science, technology and society.

The environmental benefits of hydrogen technology will eventually outweigh any drawbacks, he said.

"What is the value of the environment?

That's an important aspect to consider," he said.