Carbon footprint, that is.

Baliga, a professor of electrical and computer engineering at N.C. State, is the inventor of a power-saving switch that prevents 1.4 trillion pounds of carbon dioxide from being released into the atmosphere each year, at a cost savings of $300 billion.

And by saving 125 gigawatts of power each year, Baliga has offset the carbon footprint of 175 million people. You'd have to plant tens of millions of trees to achieve the same effect.

Now he may make big changes in the nation's electrical grid. He's a finalist for a National Science Foundation grant that would support research into how to deliver energy more efficiently.

Meanwhile, consumers already use Baliga's technology every time they turn on a television, power up a computer or switch on the air conditioning. Each year, 100,000 cardiac arrest victims are shocked back to life with his help, while, across the globe, Japanese bullet-train riders are whisked to work each morning because of his breakthrough.

Baliga, who also directs N.C. State University's Power Semiconductor Research Center, likes to joke that, "everybody uses my devices, but nobody knows it."

Baliga's chief invention, called an insulated gate bipolar transistor, or IGBT, is an improvement to the original transistors developed at Bell Laboratories in the 1940s.

As the building blocks of all modern electronics, transistors are arguably the most important invention of the 20th century. The devices amplify and switch electrical signals, and their low cost and ease of production means that millions of them can be lined up on a single microchip. But before Baliga they were very energy inefficient.

Baliga likens the concept to a garden hose: "If you think of a garden hose, you have water running through the spigot and into the hose at full speed. But if you want to control that flow, you must use a damper somewhere inside the hose to decrease the water coming out. A lot of energy is lost at the damper."

But if you could decrease the flow of the water at the spigot -- instead of sending it through at full speed and then choking off the flow with the damper -- you'd save a tremendous amount of power, Baliga says. And that's precisely what the IGBT does.

Modest, yet proud

Baliga made the IGBT breakthrough while working at General Electric. "Actually, I invented it under duress," Baliga said, since his boss had given him an ultimatum to do something profitable in six months. His innovation has made him a star in the electrical engineering community.

Scientific American has named Baliga, the author of 15 books and more than 500 scientific articles, one of eight heroes of the semiconductor revolution. The University of North Carolina's Board of Governors presented him with the O. Max Gardner award in 1998, which recognizes the member of the 16-university UNC system who has made "the greatest contribution to the welfare of the human race."

Among the few physics awards Baliga still hasn't won is the Nobel Prize. When pressed, Baliga smiles coyly and acknowledges that, at age 61, there's plenty of time left for that. Three of his fellow seven "heroes of the semiconductor revolution" are Nobel laureates.

As he discusses his many accolades, Baliga comes across as neither embarrassed nor immodest. He is visibly proud as he talks of being among the youngest men ever elected to the Institute of Electronic and Electrical Engineers and the National Academy of Engineering, yet there is no hint of self-congratulation is his tone.

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