AT&T Inc. said on March 11 it will replace or buy about 15,000 vehicles that run on alternative fuels, according to Reuters.

AT&T will spend $565 million over 10 years to stock its corporate fleet with cars and other alternative-fuel vehicles. AT&T says the investment would be the biggest of its kind by a U.S. company, significantly lowering the company's fuel costs.

About 8,000 of the vehicles will be work vans or technician trucks to be built by Ford that run on compressed natural gas. About 7,100 other vehicles will be replaced with hybrids and other advanced technology power systems. "Natural gas is cheaper, cleaner and we have plenty of it here domestically," said AT&T Chief Executive Randall Stephenson.

The hybrids will include a combination of gas-electric and plug-ins, and the trial includes mostly those made by Ford, with some from Toyota Motor Corp, according to Tim Harden, president of supply chain at the company.

T. Boone Pickens, a Texas billionaire oilman who has promoted the use of natural gas, said AT&T's actions "...will be good for their bottom line, the environment and the country."