Wind turbines, the power grid, new homes and electric cars all use it.

As the United States grapples with higher oil prices and an aging energy infrastructure, copper will be an increasingly important commodity, says a University of Wisconsin-Madison graduate student in finance.

Copper prices have backed off recently, inventories are at low levels, and there's evidence the end of China's Olympics building spree won't materially lessen demand for it in the developing world, said Jason Mirr, who is a participant in the UW-Madison business school's Applied Security Analysis Program.

Yet copper, which is an excellent conductor of heat and electricity and used in everything from coins to electric wire, water pipes, electromagnetic motors and integrated circuits, doesn't get much play.

"Gold is shiny and always on the front page. Oil, too," Mirr said. "What's not on the front page is copper. No one thinks about it, but it's one of those materials you just need."

Consider some of Mirr's examples:

- In April, Texas oilman T. Boone Pickens' Mesa Energy made a down payment on 500 wind turbines that cost $2 million each as part of a plan to build this country's biggest wind farm on 200,000 acres in the Texas panhandle at an estimated cost of $10 billion. Wind turbines use "massive amounts" of copper, Mirr said.

- Demand for electricity in the U.S. is increasing, and the power grid is in urgent need of modernization. Copper is a critical component for transmitting electricity, so a lot will be needed as the grid is rebuilt.

- Infrastructure build-outs in growing cities in developing countries like China and India are expected to keep demand for copper high.

- Many investors believe prices for building materials will fall now that the estimated $40 billion of construction spending for the Beijing Olympics has been deployed. Still, Beijing represented just 1% of Chinese demand for cement, steel and rebar, according to a "Hands-on-China Alert" published this month by JPMorgan.

Mirr is eyeing two ways to play the copper theme:

Southern Copper Corp. (PCU, $25.37), Phoenix, conducts mining operations in Peru and Mexico to produce copper, molybdenum, zinc and precious metals. It has traded as high as $47.75 and as low as $22.28 in the last 52 weeks.

Southern Copper is positioned to take advantage of copper's importance and has a stable dividend yield of nearly 10%, Mirr said.

About 75% of the company is owned by a Mexican firm that supplies transport services to Southern Copper -- a potential drawback, although the Mexican firm is protecting a customer relationship with its ownership, Mirr said.