LOS ANGELES -- Calling it a "great day in Los Angeles," former President Bill Clinton joined Mayor Antonio Villaraigosa on Monday in unveiling what is billed as the largest effort by a U.S. city to reduce pollution by retrofitting incandescent street lights with more efficient LEDs or light emitting diodes.

Over a five-year period starting in July, the city will retrofit 140,000 of its residential street lights with LEDs, officials said during City Hall news conference. The project is expected to reduce carbon emissions by 40,500 tons and save $10 million annually.

"This is the best place in the world -- in the U.S. at least -- to lead this," Clinton said, citing the city's ongoing environmental efforts. "This is like taking 6,000 cars off the road.

"If every major city followed your lead, we could eliminate 2 1/2 coal-fired power plants."

Villaraigosa hailed the effort, saying it would help make Los Angeles the "cleanest, greenest big city in the U.S. We are building a bridge to a sustainable future."

As the two men spoke, they were flanked by video displays showing workers installing the LEDs as part of a pilot project in the San Fernando Valley.

Nearby charts illustrated how the city's energy usage would fall from 197 million kilowatt-hours to 132 million kilowatt-hours over the next 10 years.

Clinton said money from the $787 billion federal stimulus package President Obama plans to sign Tuesday includes funds for environmental efforts similar to the Los Angeles street light program.

"If we help you to live green," Clinton said, there could be a time when "every major city could be without a landfill."

The ex-president began the Clinton Climate Initiative in August 2006 to help fight global warming. It is a partnership with the C40 Large Cities Climate Leadership Group, an association of large cities worldwide, including Los Angeles, that have pledged to accelerate their effort to reduce greenhouse emissions.

"The solution to the climate crisis isn't far off in the future -- it's in the buildings we inhabit, our civic infrastructure and the way we organize our lives," Clinton said at the 2007 Greenbuild International Conference in Chicago.

Clinton's visit to Los Angeles comes a day after the C-SPAN 2009 Historians Presidential Leadership Survey ranked him 15th among the 42 men who have served as president, up six spots from a year ago. Clinton was ranked third in economic management and fourth in pursing equal justice for all, but 37th in moral authority.