Tucson Unified School District is getting some national recognition for its renewable energy usage.

The Environmental Protection Agency ranked the Old Pueblo's largest school district number 2 of the country's top 30 K-12 schools generating the most green power. The district also placed 12 on the top 30 for green power production in  the entire country.

TUSD currently generates about 20 million kilowatt-hours of green energy every year from the solar energy systems scattered at various schools. That meets 20 percent of the schools' electricity use, according to a TUSD press release. The EPA says it is the equivalent to the electricity use of nearly 2,000 average American homes annually.

The district began installing solar rooftop panels—they hoped for a total of 38,000—last spring.  They anticipated to save $170,000 in the first year and more than $11 million in energy costs over the 20-year life of the 11-megawatt project, the district says. 

"Over 19,000 tons of carbon dioxide emissions will be averted from local power plants in the project's first full year of operation, along with 23.5 tons of nitrous oxides," the district says on its website.

Others on the list include Apple and Google.