BY SUSAN MONTOYA BRYAN

Associated Press

ALBUQUERQUE, N.M.

It's here, in these open expanses, that experts say is a massive untapped source of energy that could meet the nation's growing needs. But only if developers can get it out of the desert.

Even as renewable power projects get a boost from the federal government, a lack of transmission lines prevent states such as New Mexico--where the sun shines more than 300 days a year--from converting the obvious potential into real watts that can charge smartphones and run air conditioners thousands of miles away.

Aside from Phoenix, the nation's sixth-largest city, and Las Vegas, which glows around the clock, the region's rural stretches--the ideal places for acres of solar panels--have few energy demands. And sending solar power from there to population centers isn't as simple as loading coal into boxcars and shipping it cross country.

"We have incredible renewable energy resources," U.S. Energy Secretary Steven Chu said during a visit earlier this year to a solar research lab in New Mexico. "The bad news is they're where there are not many people. We need a distribution system that can accommodate that."

Transmission lines are key to developing the region's solar resources. The problem is that existing lines are maxing out, especially as the push intensifies to bring online more renewable energy. Building new lines can take years or even decades of cutting through a tangle of bureaucracy.

Spanning some 200,000 miles, much of the nation's existing transmission system is aging and will need replacement before 2030, according to preliminary findings of a new Department of Energy study on transmission congestion.

President Barack Obama reminded the nation during the Democratic National Convention that renewable power sources will play a key role in his "all of the above" energy plan.